Category Archives: Level Transmitters

Level Transmitters are sensors with an electrical transmission output,

or remote sign of liquid, powder or bulk level.

Capacitive, float, mechanical, submersible,
and ultrasonic models are the different types available of level transmitters.
Sino-Instrument offers over 50 level transmitters for level measurement.
About 50% of these are differential pressure level transmitters,
40% is the liquid level sensor,
and 20% are Ultrasonic Level Transmitter and radar level transmitter.
A wide variety of level transmitters options are available to you,
such as free samples, paid samples.
Sino-Instrument is a globally recognized supplier and manufacturer of level measurement instrumentation,
located in China.
The top supplying country is China (Mainland),
which supply 100% of the level transmitters respectively.
Sino-Instrument sells through a mature distribution network,
that reaches all 50 states and 30 countries worldwide.
Level transmitter products are most popular in Domestic Market,
Southeast Asia, and Mid East.
You can ensure product safety by selecting from certified suppliers,
with ISO9001, ISO14001 certification.

If you want to know What is the level transmitter working principle?

You should know:

What are the different types of level transmitters?

There are many different kinds of level measurement transmitters, including:

  • Capacitance
  • Hydrostatic
  • Magnetic
  • Radar
  • Ultrasonic
  • Guided Microwave

Each of these transmitters works in different ways, making them useful for different types of processes.

  • Capacitance Level Transmitters:
These transmitters use liquid stored in a tank or container,
as a dielectric medium between two or more electrodes.
The energy capacity of the capacitor circuit increases,
when there is more liquid and decreases if there is less liquid. By measuring the variations in the capacitance value,
capacitance level transmitters can calculate the current fill level of the tank or container.

Capacitance Level Transmitters:

  • Hydrostatic Level Transmitters::
Also known as pressure level transmitters,
these transmitters help in determining fluid contents of a container,
by measuring the pressure of the resting body of the fluid within it. The greater the force of liquid, the greater the volume of fluid.
  • Magnetic Level Transmitters:
These transmitters use a magnetic object,
which is suspended in a buoyant float.
This is usually in a narrow auxiliary column,
to restrict lateral movements of the float.
While the float is on top of the liquid,
the movement of the float is measured by a different magnetic device.
This allows a precise and stable fill level to be transmitted.
This method is suitable for continuous measurement,
owing to the tendency of the float to rise or sink based on the liquid level.
  • Radar Fill Level Transmitters:
These transmitters work on the principle of radar by using radio wave emissions.
These transmitters are normally mounted at the top of a tank filled with a liquid.
The transmitter sends a radar signal into the liquid and receives a reflection of the signal.
The transmitters then analyze the current fill level of the tank based on the time taken by the transmitted signal to return.
  • Ultrasonic Level Transmitters:
In this type of transmitter, an ultrasonic transducer is mounted at,
or near the top of a container containing liquid.
The transducer sends out an ultrasonic pulse.
The pulse hits the surface of the liquid and gets reflected.
The sensor then calculates the fill level based on the time between the transmitted and received signal.
  • Guided Microwave Level Transmitters:
These transmitters work by sending a microwave pulse,
through a sensor cable or rod.
The signal hits the surface of the liquid,
and travels back to the sensor,
and then to the transmitter housing.
The electronics integrated into the transmitter housing
determine the filling level based on the time,
taken by the signal to travel down the sensor and back up again.
These types of level transmitters are used in industrial applications,
in all areas of process technology.
Choose the right level transmitter for your application:

Cryogenic Level Sensor: Selection Guide for LN2, LOX, LAr, LNG & LH2

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A cryogenic level sensor measures the liquid level of nitrogen, oxygen, argon, hydrogen, or LNG inside vacuum-jacketed (VJ) tanks at temperatures between −162 °C and −253 °C. Because every cryogen has its own dielectric constant, vapor pressure, and stratification behavior, the right sensor changes with the fluid — capacitive probes work for LN2 and LAr, hydrostatic DP transmitters dominate LOX and LNG bulk tanks, and only specialised resistive or superconducting probes survive LH2. This guide picks the technology by fluid, by tank type, and by safety class.

Contents

Why Cryogenic Level Is Different From Ambient Service

A cryogenic tank is never a closed pot of cold liquid. It is a thermodynamically active vessel where the gas head is constantly being generated by boil-off, the liquid is constantly stratified into a warmer top layer and a colder bulk, and the wetted parts of the level sensor see a 200 to 270 K temperature step. That single fact rules out most ambient-service level technologies.

Three failure modes matter most. Cold-shock crack on glass-filled probes during a fast fill, ice plug on any vent line that touches ambient humidity, and density error on hydrostatic measurement when the saturated boil-off layer sits between the head pressure tap and the liquid. A correctly specified cryogenic level sensor solves all three through material choice (austenitic 304/316L or 9% Ni for LNG), a vacuum-jacketed extension neck or stilling well, and a vapor-corrected level algorithm.

The legacy ASME B31.3 and CGA-341 rules for cryogenic piping carry over to level instrumentation: every wetted thermowell, flange, and probe needs a documented cryogenic temperature rating, and any gauge connected to a hydrogen service must additionally meet IEC 60079 IIC zone classification with an internal flame arrestor.

Five Cryogens, Five Sets of Sensor Constraints

The fluid drives the sensor. The table below summarises the four properties that decide which level technology survives: boiling point at 1 atm, liquid density, relative dielectric constant εr, and the highest safety risk class. Use it as the first sieve before discussing specific products.

CryogenBP @ 1 atmLiquid ρ (kg/m³)εr (liquid)Primary riskWorkable level tech
Liquid Nitrogen (LN2)−195.8 °C8081.43Asphyxiation, cold burnCapacitive, DP, magnetostrictive
Liquid Oxygen (LOX)−183.0 °C11411.49Oxidiser ignitionDP (LOX-cleaned), capacitive (Cu-free)
Liquid Argon (LAr)−185.9 °C13941.50AsphyxiationCapacitive, DP, magnetostrictive
Liquid Natural Gas (LNG)−161.5 °C422 to 4701.66 to 1.85Flammable IIADP, servo, GWR with PTFE seal
Liquid Hydrogen (LH2)−252.9 °C711.23Flammable IIC, hot spotSuperconducting wire, resistive C-glass, DP

Two numbers in the table do most of the work. A liquid density of 71 kg/m³ (LH2) means a 5 m tall tank generates only 3.5 kPa of hydrostatic head — close to the resolution floor of a 25 kPa DP cell, which is why pure DP rarely works on hydrogen. And an εr of 1.23 for LH2 versus 1.49 for LOX is the reason a capacitive probe calibrated for liquid oxygen will under-read LH2 by roughly 50% if the user does not retune.

Capacitive Probe in Liquid Nitrogen and Argon Tanks

The capacitive cryogenic level sensor is the workhorse for LN2, LAr, and most laboratory dewars. It is a coaxial probe — an inner stainless rod surrounded by an outer perforated tube — immersed vertically through the tank top flange. The capacitance between the two electrodes scales linearly with the immersed length because the dielectric constant of LN2 (1.43) is far below the gas-phase εr (1.0006).

A simple coaxial form gives C = 2πε₀εrL / ln(b/a), where a and b are the inner and outer radii and L is the wetted length. For a typical 6 mm inner / 12 mm outer probe immersed 1 m in LN2, the capacitance change between empty and full is around 75 pF — large enough that a 1 mm resolution is achievable with off-the-shelf 4–20 mA transmitters.

Two practical mistakes show up on commissioning. First, contractors run the probe cable through the same conduit as a ground-side heater wire, picking up 50/60 Hz noise that breaks the 1 mm resolution claim — the fix is a separate, shielded twisted pair grounded only at the transmitter end. Second, the probe is left dry-calibrated and then dropped into LN2; a 200 K cold-shock causes the PTFE bushing inside the probe head to contract more than the stainless rod, opening a leak path. Soak the probe in vapor for 60 seconds before full immersion to avoid this.

Differential-Pressure Level on LOX, LIN, and LNG Bulk Tanks

Differential-pressure level is the dominant technology on LOX, bulk LIN, and most onshore LNG storage above 50 m³. It uses two diaphragm-seal cells — one at the bottom of the tank reading liquid + gas pressure, one at the top reading gas pressure only — and the level is computed as L = (Pbottom − Ptop) / (ρ · g). The vapor-corrected output is automatic because both cells share the gas head.

Three details separate a working DP install from a drifting one. The capillary fill fluid must be silicone DC-704 for LN2 and LAr (good to −90 °C inside the capillary), but for LOX it must be LOX-cleaned Halocarbon 0.8 oil to avoid an oxygen-promoted ignition path. The bottom diaphragm has to sit on a vacuum-jacketed flange spool so the wetted face stays at tank temperature; otherwise vapor flashes inside the seal cavity and corrupts the head reading. And the top tap needs to draw from the gas dome at least 300 mm above the maximum operating level to avoid liquid pickup during a roll-over event.

For LNG, density correction matters more than for LIN. LNG density varies from 422 kg/m³ (warm boil-off-rich) to 470 kg/m³ (cold sub-cooled), which is an 11% spread. Modern smart DP transmitters take a temperature input from a tank RTD and apply a stored density curve so the level reading does not drift across that envelope.

Magnetostrictive and Magnetic-Float Indicators for Dewars

Magnetostrictive level transmitters work on small mobile dewars and on the side-mounted level-sight chambers of vertical LN2/LAr tanks where capacitive probes are not practical. The principle is unchanged from ambient service — a torsion pulse traveling along a nickel-iron wire is reflected by a magnetic float — but the float, the stem material, and the head seal must all be qualified at −196 °C. A standard ambient-service magnetostrictive will fail at the float magnet (room-temperature NdFeB loses 10% of its remanence at 77 K and develops cracks below 60 K) within 50 thermal cycles.

For dewar service, specify a SmCo (samarium-cobalt) float magnet, an Inconel 625 stem, and a vacuum-jacketed head extension. With those upgrades, the device delivers 1 mm resolution and survives 1000+ thermal cycles. Magnetic-flap visual indicators (no power, no electronics, just a chain of red/white flippers driven by the moving magnet) remain popular as a backup readout on safety-critical LN2 storage rooms because they keep working when the SCADA is offline.

Superconducting and Resistive Probes for Liquid Hydrogen

Liquid hydrogen needs a different physics altogether. The 71 kg/m³ density makes hydrostatic DP marginal, and the εr of 1.23 makes capacitance probes only twice as sensitive as gas-phase — not enough for production tanks. Two technologies dominate large-scale LH2 storage at NASA, ITER, and merchant H2 plants.

Superconducting wire probes use a multi-strand NbTi or Nb3Sn wire stretched vertically inside the tank. Above 9.2 K the wire is resistive (about 0.4 ohm/m); below it the wire is superconducting (zero ohm). Liquid hydrogen at 20.4 K cools the wetted segment below the superconducting transition while the gas-phase segment stays normal. The resistance ratio reads out level directly with sub-mm resolution. Because the wire dissipates only 50–200 mW, parasitic boil-off is negligible.

Resistive carbon-glass thermometer ladders are the simpler alternative. A vertical chain of 20 to 50 carbon-glass thermometers reads an order-of-magnitude resistance step on the wetted vs gas-phase elements. Resolution is set by sensor spacing (typically 50 mm) and the technology is fully compatible with IIC explosion-proofing, which is why most road-tanker LH2 trucks use it.

Installation, Boil-Off, and Stratification Rules

Three install rules apply across every cryogen and every technology. Each one corrects an error we routinely see on commissioning visits.

  1. Slow-fill the probe before service. Vent the tank to atmosphere, crack the fill valve, and let cold vapor flow past the probe for 60–120 seconds before liquid covers it. Direct liquid hit on a warm probe will fracture glass-fibre PCB substrates inside the head.
  2. Use a stilling well in agitated tanks. Pumping LN2 into a transport bullet creates surface waves of 50–150 mm. A perforated 100 mm stilling pipe surrounding the probe damps the waves below 10 mm and stops the level loop from running away.
  3. Compensate for stratification on bulk LNG. A 30 m LNG tank can have a 0.5 K stratification top-to-bottom, which becomes a 3% density error. Pair the level transmitter with two RTDs (top quarter, bottom quarter) and let the smart DP cell apply density correction in real time.

Boil-off itself is rarely a level-sensor problem on LIN or LAr (typical evaporation rate is 0.3 to 1% per day on a well-insulated VJ tank), but on LNG bulk storage, a 0.05 to 0.15% boil-off rate combined with the 11% density spread means the level loop must be filtered to a 30-second moving average to avoid actuator hunting. For LH2, boil-off climbs to 1 to 3% per day on smaller dewars, and the level reading is normally combined with a mass-flow boil-off integrator to compute usable inventory.

Capacitive Level Sensors

Capacitive Level Sensors

Coaxial RF capacitance probes for LN2 and LAr dewars. PTFE-isolated stainless rods, 304/316L wetted parts, 4–20 mA HART output. 1 mm resolution on 1 m immersion in nitrogen and argon.

SMT3151LT DP Level Transmitter

Smart DP cell for vapor-corrected level on LOX, LIN, and LNG bulk tanks. Halocarbon-fill capillary option for LOX service, ATEX/IECEx Ex d, density-compensation block built in.

Cryogenic Pressure Transducers

VJ-rated pressure transducers for hydrostatic level on LH2 and LHe service. −269 °C operating, IIC zone certification, mass-balance level computation when paired with a top-of-tank reference cell.

Need help matching one of these to your tank geometry, fluid, and area classification? Tell us the cryogen, the tank height, the operating pressure, and whether the service is bulk storage or a transport dewar — we will return a model-specific recommendation with capillary fill and material call-outs the same business day. For broader level technology context, see our overview of level measurement technologies and the DP level transmitter selection notes. Tank-form factors that affect probe placement are covered in our tank-bottom hydrostatic level guide, and our SI-100 magnetostrictive level transmitter page covers the SmCo float upgrade for dewar applications.

FAQ

What is the most accurate way to measure liquid nitrogen level in a dewar?

A coaxial capacitive probe with a SmCo-magnet stilling well delivers 1 mm resolution on a 1-metre LN2 immersion. Hydrostatic DP works but is limited by the LN2 density of 808 kg/m³ and is normally reserved for tanks above 5 m tall. For sub-millimetre laboratory work, a superconducting wire probe is the only option.

Can a standard 4–20 mA pressure transmitter work as an LN2 level sensor?

Only if it is qualified to −196 °C and the tank has a stable gas head. A non-VJ ambient pressure transmitter mounted on the bottom flange will read correctly until vapor flashes inside the impulse line and locks the reading. Use a vacuum-jacketed bottom-tap configuration or a dedicated cryogenic pressure transducer.

Why does my capacitive LN2 level sensor read 5% high after a fast fill?

Surface foam from a high fill rate creates a 50–150 mm wave layer with a higher effective εr than the bulk liquid. Slow the fill below 50 litres per minute or install a perforated stilling well around the probe; the reading will normalise within 60 seconds.

Are LOX level sensors interchangeable with LN2 level sensors?

Mechanically yes; chemically no. LOX-rated equipment must be cleaned to ASTM G93 Level C, which forbids hydrocarbon residues. A capacitive probe used in LN2 service that has not been LOX-cleaned creates a documented oxidiser-ignition hazard if transferred to LOX service.

How do I measure liquid hydrogen level in a small research dewar?

For dewars below 100 L, a carbon-glass thermometer ladder gives the best price-to-resolution ratio. The wetted carbon-glass elements show roughly a 5× resistance step at the LH2 surface and the technology is intrinsically IIC compatible. Above 100 L, a NbTi superconducting wire probe is preferred for the continuous-readout advantage.

What is the typical accuracy of a DP level transmitter on LNG bulk storage?

With a smart DP cell and density compensation from two RTDs, level accuracy is ±0.1% of span on a 30 m tank, equivalent to about 30 mm. Without density compensation, the same install drifts to ±1% across the warm-cold density envelope of LNG.

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SI-100 Rigid Probe Magnetostrictive Level Transmitter | 0.2-6 m, ±0.1 mm

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SI-100 Rigid Probe Magnetostrictive Level Transmitter

Stainless probe, 0.2 to 6 m measuring range, ±0.1 mm accuracy, 4-20 mA / HART / Modbus, ATEX option. Built for atmospheric and pressurized tanks where you need a rigid stem instead of a flexible cable.

  • Range: 0.2-6 m rigid. Up to 23 m with flexible cable variant.
  • Accuracy: ±0.1 mm or 0.05 % of FS, whichever is greater.
  • Output: 4-20 mA + HART, RS-485 Modbus RTU, or 0-10 V.
  • Process: -40 to +125 °C standard, +200 °C with extension. PN16/PN40 flange or 1″ NPT.
  • Certifications: ATEX/IECEx Ex ia IIC T6 Ga (Zone 0 capable). IP67.
Request a Quote View Full Specs ↓

Why Engineers Spec the SI-100

Four reasons it gets picked over float, ultrasonic, or guided-wave radar in our daily quote requests.

±0.1 mm

Repeatable Accuracy

Better than float by ~50× and better than 4-20 mA radar by ~10× for tanks under 6 m.

No Drift

Time-of-Flight Reading

The torsional pulse on the waveguide does not drift with temperature, dielectric, or coating.

2 Outputs

4-20 mA HART + Modbus

Drops into a PLC analog input or a Modbus poll loop without buying a new transmitter.

ATEX Ex ia

Zone 0 Capable

Same body as the standard model; just add the safety barrier on the cabinet side.

Full Specification Sheet

What you will see on the line item of the quote. Download the PDF datasheet from the request form below.

ItemSI-100 StandardSI-100 Ex (ATEX/IECEx)
Probe typeRigid stainless rod, 316LRigid stainless rod, 316L
Measuring range0.2 m – 6 m0.2 m – 6 m
Resolution0.01 mm0.01 mm
Linearity±0.05 % FS or ±0.1 mm (greater)±0.05 % FS or ±0.1 mm (greater)
Repeatability±0.005 % FS±0.005 % FS
Output4-20 mA / HART / Modbus RTU / 0-10 V4-20 mA + HART (Ex ia) / RS-485 (Ex ia)
Power supply24 VDC ±10 %24 VDC via Ex ia barrier
Process temperature-40 to +125 °C (+200 °C with extension)-40 to +85 °C (T6) / -40 to +120 °C (T5)
Process pressure0 – 4 MPa (40 bar)0 – 4 MPa (40 bar)
Process connection1″ NPT / G1″ / DN50 PN16 / DN50 PN40 flangeSame as standard
Float (included)SUS304 ring float, 50 mm OD, ≥ 0.6 g/cm³SUS304 ring float with Ex cable gland
HousingAluminum die-cast, IP67Aluminum die-cast, IP67
Cable entryM20 × 1.5M20 × 1.5 with Ex cable gland
Hazardous areaSafe area onlyEx ia IIC T6…T4 Ga (Zone 0)
ApprovalsCE, RoHSCE, RoHS, ATEX, IECEx

How Magnetostriction Actually Measures Level

  1. The transmitter head fires a low-current interrogation pulse down a tensioned waveguide wire inside the rigid stem.
  2. A donut float wrapped around the stem carries a permanent magnet. Where the pulse meets the magnetic field, the wire twists slightly — that twist is a torsional pulse.
  3. The torsional pulse travels back up the waveguide at ~2,830 m/s. The transmitter clocks the round-trip time.
  4. Distance = ½ × travel time × wave speed. A 1 GHz timer gives 0.01 mm resolution.

Why it matters in the field: no capacitance plate to coat, no ultrasonic beam to scatter on foam, no microwave dielectric to fight. The pulse is mechanical and the trigger is magnetic, so dirty liquids, vapors, and dielectric changes do not affect the reading.

Where the SI-100 Fits (and Where It Doesn’t)

The rigid-stem version owns four common tank shapes. If your tank looks like one of these and the depth is under 6 metres, the SI-100 is a one-line BOM addition.

Ceiling / Suspended Tanks

Top-mount through a flange. Probe length picked to leave 50 mm dead zone at the bottom. Common in chemical dosing rooms.

Buried Fuel Tanks

Diesel, petrol, or AdBlue. 4-20 mA + HART output feeds station controllers. Choose Ex ia version for petrol.

Small Process Containers

Day tanks, mixing vessels, lube reservoirs. Short probe (300-800 mm) keeps the float stable in narrow geometry.

Agitated / Foaming Tanks

Use the external stilling-well variant. The float sits inside a side chamber so the agitator does not whip it around.

When NOT to spec the SI-100: tanks deeper than 6 m (use flexible-cable variant or guided-wave radar), liquids with floating crust or solid foam thicker than 20 mm, and any liquid with metallic suspended solids that could stick to the float.

Three Ways to Mount It

Tell us which one fits your tank when you request the quote and we will ship the right adapter pre-fitted.

1. Top Mount (Thread or Flange)

Default option. 1″ NPT, G1″, or DN50 PN16/PN40. Probe drops straight down through the tank top.

2. Positioning Ring

For tanks where you cannot drill a flange. A clamping ring holds the rigid stem at the top opening.

3. External Stilling Well

Side-mounted chamber connected by upper and lower process taps. Used for agitated, foamy, or coating liquids.

Sizing the Probe Length

The probe is cut to order. Get this wrong and you either lose dead-band at the top or pay for steel you do not need. Three numbers go on the quote:

  1. H1 — Top Dead Zone: 50 mm minimum from the flange face down to the highest reading point. Add the height of the top fitting (a DN50 flange eats 30-60 mm).
  2. H2 — Live Measuring Length: the distance you actually want to read. Make this the working range you care about, not the full tank height.
  3. H3 — Bottom Dead Zone: 50 mm fixed, set by where the float magnet sits on the end stop.

Total probe length = H1 + H2 + H3, rounded up to the nearest 50 mm. For a tank 1.2 m tall with full coverage, order a 1300 mm probe (50 + 1200 + 50).

Two real-world examples from quotes we shipped last quarter:

TankWorking Level NeededProbe OrderedOutput Wired To
2.5 m vertical day tank, diesel0 – 2.4 m2500 mm rigid, 4-20 mA HARTAllen-Bradley AI card
0.8 m mixing vessel, IPA0.1 – 0.7 m800 mm rigid, Modbus RTU, Ex iaSchneider M340 RS-485
4.2 m underground petrol tank0 – 4.0 m4200 mm rigid, 4-20 mA HART, Ex iaStation controller

Pricing and Lead Time

FOB Shanghai, EXW China for orders ≥ 5 units. Stock items ship in 5 working days; configured items 10-15 days.

ConfigurationProbe LengthUnit Price (USD, Qty 1-4)Lead Time
SI-100 Standard, 4-20 mA≤ 1.0 m$6805 days (stock)
SI-100 Standard, 4-20 mA + HART≤ 2.0 m$88010 days
SI-100 Standard, Modbus RTU≤ 3.0 m$1,15010 days
SI-100 Ex ia, 4-20 mA + HART≤ 6.0 m$1,65015 days
SI-100 with Stilling-Well ChamberConfigured$1,950 +15 days

Bulk pricing (10+ units) drops 12-18 % depending on configuration. Quote turnaround is the same business day for any spec listed above.

If the SI-100 Doesn’t Fit Your Tank

Three alternatives we ship for the cases the rigid SI-100 cannot cover:

Flexible-Cable Magnetostrictive →

For tanks 6-23 m deep. Cable instead of rigid stem. Same accuracy, easier shipping.

Magnetic-Flap Level Gauge →

When you need a visible local indicator (flap column) plus the 4-20 mA signal in one device.

SMT3151 Hydrostatic →

Cheaper for water and benign liquids if ±0.1 mm is overkill. Submersible or threaded.

Frequently Asked Questions

What’s the Longest Rigid Probe You Will Build?

6 metres. Beyond that the rigid stem is hard to ship and to install, so we switch you to the flexible-cable variant which goes to 23 m.

Will It Work With Diesel That Has Water at the Bottom?

Yes, with two floats. The dual-float SI-100 gives you total liquid level (top float on diesel) and water-interface level (lower float on the diesel/water boundary). Specify on the quote.

Can I Retrofit It Where a Guided-Wave Radar Used to Be?

If the existing flange is DN50 or 1″ NPT, yes — drop-in. The 4-20 mA + HART output keeps your DCS configuration unchanged.

Does the Float Density Matter?

Standard SUS304 ring float works for liquids ≥ 0.6 g/cm³. For lighter liquids (like LPG condensate at 0.55 g/cm³) we ship a low-density titanium or PTFE float. Tell us the SG when you request the quote.

Which Output Should I Order for a Siemens S7-1500 PLC?

4-20 mA + HART for the simplest path (S7-1500 has analog input cards). If you are already on Profibus or Profinet, take the Modbus RTU version and run it through a gateway.

How Is the SI-100 Calibrated Before Shipping?

Each unit is bench-tested with the actual ordered float against a precision linear stage. A two-point calibration certificate (4 mA at empty, 20 mA at full) is included in the box. Field calibration is rarely needed.

Get a Confirmed Quote and PDF Datasheet

Tell us tank height, liquid, mounting style, and your PLC, and we will come back with a unit price and the full PDF datasheet within one business day.

Request a Quote

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DP Level Transmitter for Tank Level Measurement

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The DP level transmitter works on the principle that the hydrostatic pressure difference of a liquid is directly proportional to the liquid level height. It calculates the liquid level by measuring the pressure difference of the medium inside the container and outputs a standard electrical signal. The dual-flange capillary structure provides mechanical and thermal isolation, allowing it to handle complex corrosive and high-temperature media in various industrial processes and tank level monitoring applications.

Sino-Inst offers a variety of DP Level Transmitters for industrial pressure measurement. Connection with diaphragm seals. If you have any questions, please contact our sales engineers.

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More DP Transmitters

Features

  • Exd II CT6 Gb/ Exia II CT6 Ga, suitable for direct use in hazardous areas and outdoors;
  • All sensor components are made of 316L stainless steel;
  • 316 stainless steel diaphragm, convenient installation with movable flange;
  • 6 diaphragm materials available: 316L diaphragm, HC276 diaphragm, tantalum diaphragm, 316L fully coated diaphragm, gold-plated diaphragm, PTFE diaphragm, etc., customizable;
  • High-precision configuration, optional 0.1%FS, 0.075%FS;
  • Extremely high anti-interference and stability;
  • 275-point temperature, pressure, and current compensation;
  • LED LCD display, 0-100% percentage display, and real-time liquid level value display;
  • Output: 4-20mA + HART/RS485;
  • Nitrogen pressurized base, superior sealing performance, nitrogen pressurization prevents leakage.

Specifications of DP level transmitter

Measuring Medium:Gases, Vapors, Liquids
Measuring Range-100kPa…0~6kPa…7MPa
Accuracy:±0.075%, ±0.1%, ±0.2% (including linearity, hysteresis, and repeatability from zero point)
Stability:±0.2%/year
Power Supply:10–36V DC (24V DC recommended)
Reference Accuracy for Range Adjustment:If TD > 10 (TD = Maximum range / Adjustable range), then: ±(0.075 × TD)%
Ambient Temperature:-40℃ ~ 85℃
Measuring Medium Temperature:-40℃ ~ 400℃ (higher/lower temperatures can be customized)
Storage Temperature:-40℃ ~ 85℃
Display:LCD, OLED
Display Module Temperature:-20℃ ~ 70℃ (LCD), -40℃ ~ 80℃ (OLED)
Measuring Diaphragm:316L, Hastelloy C, Tantalum, Titanium, Nickel, Monel, Duplex Stainless Steel, PFA, Gold Plating
Process Connection:Stainless steel 316L, 304
Filling Fluid:Silicone oil, fluorinated oil, etc.
Transmitter Housing:Aluminum alloy material, epoxy resin coating on the surface
Housing Seal:Nitrile rubber
Nameplate:Stainless steel 304
Enclosure Protection Rating:IP67
Explosion Protection Rating:Exd Ⅱ CT6 Gb, Exia Ⅱ CT6 Ga
Measuring Range LimitsWithin the upper and lower limits of the range, it can be set arbitrarily, as long as the calibrated range ≥ the set range. It is recommended to choose a range with the lowest possible range ratio to optimize performance.
Influence of Mounting PositionChanges in installation position will cause zero point influence, which can be corrected by zero adjustment; there is no range influence.
OutputTwo-wire 4-20mA, compliant with NAMUR NE43 standard, superimposed digital signal (Hart protocol)
Output Signal LimitsImin (minimum): 3.9mA Imax (maximum) = 21.0mA
Alarm CurrentLow alarm mode (minimum): 3.9mA High alarm mode (maximum): 21mA (user pre-settable)
Default Alarm Current SettingHigh alarm mode
Fault WarningIf the sensor or circuit fails, the automatic diagnostic function automatically outputs 22.0mA
Response TimeAmplifier component damping constant is 0.1s; sensor time constant is 0.1–1.6s, depending on the range and range ratio. Additional adjustable time constant: 0–100s
Warm-up Time<15s

There are 5 types of remote transmission devices for remote differential pressure transmitters:

  1. Flat type
  2. Thread mounting type
  3. Flange mounting type
  4. Extended Diaphragm Seal
  5. Wet legs/Dry legs
SM3151LT liquid level pressure-differential pressure transmitterDownload

Applications of DP level transmitters

The differential pressure liquid level transmitter can prevent the measured medium from directly contacting the sensor diaphragm of the transmitter. It is suitable for the following situations:

  1.  When the measured medium has a corrosive effect on the transmitter connector and sensitive components;
  2. When the high temperature measured medium needs to be isolated from the transmitter;
  3. When there are solid suspended solids or high viscosity in the measured medium, it is easy to block the transmitter connector and the pressure chamber;
  4. When the measured medium is easily cured or crystallized by the pressure tube;
  5. When changing the measured medium needs to be rinsed and not to be mixed;
  6. Hygienic conditions must be maintained to prevent pollution. .
  7. Changing the measured medium requires strict purification of the measuring head
  8. Suspended liquid or high viscosity medium
  9. Measurement of sealed pressure vessel.

Read more What is a diaphragm seal?

DP level transmitter working principle

The differential pressure level transmitter is an instrument that uses the pressure generated by the liquid column to measure the height of the liquid level. When the liquid level changes, the pressure received by the diaphragm at the high-pressure side flange will change accordingly. The differential pressure value calculated by the transmitter will also change accordingly. There is a linear relationship between them.

Normally, the high-pressure side (H side) and the low-pressure side (L side) cannot be installed reversely. Generally, the H side is installed at the lower part of the equipment, and the L side is installed at the higher part of the equipment. Before installation, the flange surface of the equipment should be cleaned and the gasket should not be placed off-center to prevent the diaphragm from being punctured or deformed, causing distortion of the transmitter.

SMT 3151 Differential Pressure Level Measurement

Differential pressure transmitter level measurement calculation

When using a Differential pressure (DP) level transmitter to measure the liquid level as shown in the figure below.

The measured liquid density in the figure is ρ.
The working medium density in the capillary of the double flange differential pressure transmitter is ρ0.
The measuring range of the measured liquid level is H.
The center distance of the sampling tube of the measured liquid level is h.

It can be seen from the figure that the maximum measurement range of the liquid level △ P = P + — P- = H × ρ × g – h × ρ0 × g.

It can be seen from the formula that the dual-flange differential pressure transmitter should perform negative migration. The migration amount S is h × ρ0 × g. And the installation position of the double flange differential pressure transmitter has no effect on the migration amount and the measurement result.

The dual-flange differential pressure transmitter requires negative migration.

When the measured liquid level is 0, the pressure difference between the positive and negative measurement chambers of the remote differential pressure transmitter is the largest. The output current of the double flange differential pressure transmitter is 4mA.

As the measured liquid level rises, the pressure difference between the positive and negative measurement chambers of the transmitter gradually decreases.

When the measured liquid level rises to the highest Hmax. The pressure difference between the positive and negative measurement chambers of the transmitter is the smallest. The output current of the double flange differential pressure transmitter is 20mA.

Read more about: Differential Pressure Transmitter Installation Guide

DP level transmitter calibration

The differential pressure liquid level transmitter has been calibrated in the range, accuracy, linearity and other parameters according to customer requirements at the factory. And mark the range, accuracy, etc. on the nameplate of the differential pressure liquid level transmitter. As long as the density and other parameters of the measured medium meet the requirements of the nameplate, generally no adjustment is required.

If the customer needs to adjust the range or zero position, please adjust according to the following methods. Assuming that the range of the differential pressure liquid level transmitter is 0 ~ 10 meters:

https://www.drurylandetheatre.com/wp-content/uploads/2019/03/SMT-3151-Differential-Pressure-Level-Measurement-supplier.mp4
  1. Unscrew the protective cover of the differential pressure liquid level transmitter. It can be adjusted by connecting an external standard 24VDC power supply and ammeter (requires accuracy of 0.2% or above).
  2. When there is no liquid in the differential pressure liquid level transmitter. Adjust the zero potentiometers. Make it output a current of 4mA.
  3. Pressurize the differential pressure liquid level transmitter to full scale (10 meters). Adjust the full-scale resistor. Make it output a current of 20mA.
  4. Repeat the above steps two or three times until the signal is normal.
  5. Please input 25%, 50%, and 75% signals to check the error of the differential pressure liquid level transmitter.
  6. For non-aqueous media. Differential pressure level transmitters are calibrated with water. It should be converted according to the pressure generated by the actual density of the medium. For example, when the medium density is 1.3, the 1.3m water level should be used to calibrate the 1m range.
  7. After adjustment, tighten the protective cover.
  8. The verification cycle of the differential pressure liquid level transmitter is once a year.
  9. HART intelligent differential pressure liquid level transmitter of Sino-Inst instrument can be selected. It is convenient to adjust the range of the differential pressure liquid level transmitter.

Extended reading: How to calibrate HART pressure transmitters

More Featured DP Transmitters

Smart Differential Pressure Transmitter
Flange Mounted DP Transmitter
Extended Diaphragm Seal DP Level Transmitter
Remote Seal Differential Pressure Transmitter

More Pressure and Level Measurement Solutions

Sino-Inst (drurylandetheatre.com) offers over 20 DP transmitters for liquid level, pressure, flow, and density measurement. Differential pressure (DP) level transmitters are suitable for measuring water and other liquid levels.

We are a differential pressure level transmitter supplier, located in China. Our products are widely exported to the United States, Australia, Singapore, Indonesia, etc. You can ensure product safety by selecting from our products, including IOS9000, and… certification.

Of course, in addition to differential pressure transmitters, pressure transmitters can also be used to measure the liquid level in open tanks. If you need to purchase Level Transmitters or have related technical questions, please feel free to contact our sales engineers!

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807 Low Temperature Liquid Level Sensor

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807 Low Temperature Liquid Level Sensor is a customized product specially designed for liquid level measurement in low temperature environments such as liquid nitrogen, LNG, and liquid ammonia. -196℃~80℃ available.

This product has no moving parts and is not disturbed by the external environment. It has the advantages of stable and reliable long-term operation, high sensitivity, good linearity, low temperature resistance and corrosion resistance. The cryogenic level meter provides a variety of output signals RS232\ RS485\ 0～5V \4～20mA.

RFQ

Technical Parameters

No.ItemCurrent sensor metricsCustomizable
1Operating VoltageDC12V~24V5V~36V
2Detector working temperature-196℃～80℃custom made
3Ambient temperature-40℃~80℃-40℃~80℃
4Detection lengthAs shown on the nameplate50mm~3000mm
5Pressure range≤ 1.6MPaSpecial customizable
6Probe diameterΦ16            Φ8~Φ25
7Installation methodM20*1.5M10~M30/NPT/G/sanitary chuck
8Explosion-proof level2088 explosion-proof shell2088 explosion-proof shell/304 stainless steel micro shell
9Accuracy level1.0/2.00.5/1.0/2.0
10Output signal4~20mA4~20mA/0~5V/RS485/RS232

807 Low Temperature Liquid Level Sensor Wiring

The connection position is equipped with integrated 4-bit terminal, defined as shown in Figure:

OUT +: Power Supply +
OUT-: Power Supply-
TEST +: Debug the interface
TEST-: Debug the interface
Note: The sensor TEST (R485) for 4 ~ 20 mA signal is for commissioning only

Precautions for use

  1. There can only be one type of RS232/RS485/0-5V/4~20mA signal, and you can choose to use any one of them. The RS485 bus can connect multiple sensors at the same time, but the communication address of each sensor must be set in advance. The communication address of each sensor must be unique to prevent the bus from locking up. The RS485 bus uses a half-duplex chip, so the module should be allowed time to respond when reading data. The reading speed cannot be too fast. The time interval between two instructions during continuous reading cannot be less than 200ms.
  2. It is recommended that the sensor be connected with a shielded wire, especially for RS232 communication. The communication wire should not be too long.
  3. For RS232/RS485 signal sensors, when troubleshooting communication failure, you can swap the blue and yellow wires for testing. If the communication is successful, it means there is a wiring error. This operation is for digital communications only.
  4. The power supply voltage of the sensor shall not exceed its normal working voltage, and the power consumption of the sensor power supply shall not be less than the power consumption of the sensor during normal operation.
  5. The actual environment should meet the basic parameter requirements of the sensor and must not exceed the normal range, otherwise it will cause damage to the sensor and even cause other accidents.
  6. The sensor outputs the position height signal of the medium. When the filtering is zero, the output value reflects the actual change of the liquid level. The output value changes with the rise or fall of the liquid level. After adding the filtering, the value will Becomes stable and lagging, the larger the filter value, the higher the temperature, the liquid level value will lag behind the change of the actual liquid level. Therefore, customers adjust the filter value based on device usage.
  7. Please do not disassemble or damage the sensor maliciously, otherwise the warranty will be void.
  8. All accessories such as rubber pads and O-rings of the sensor are not covered by the warranty.

More Low Temperature Liquid Flow and Pressure Measurement

Low temperature Turbine Flowmeter-Liquid Nitrogen Flow Meter
Gear flow meter for Micro flow
U-Series Liquid Mass Flow Meter
T-series Triangle Coriolis Mass Flowmeter
SI-512H High and Low Temperature Pressure Sensor
SI-706 Combined Pressure and Temperature Sensor-Dual function
Cryogenic Pressure Transducer
High Frequency Dynamic Pressure Sensor

807 Low Temperature Liquid Level Sensor is a customized sensor, which is limited to the measurement of low-temperature liquid level and cannot be used for other media.

We, Sino-Inst, are a professional high-tech enterprise focusing on the research and development, production, sales and engineering services of liquid level/pressure/flow sensors and transmitters, intelligent instruments and automated control systems. Our main products include liquid level, pressure and flow sensors, transmitters and other field measurement instruments.

We provide customers with measurements under various high temperature, low temperature, explosion-proof and other special working conditions. If you need Low Temperature Liquid Level measurement, please feel free to contact our sales engineers.

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Radar Water Level Sensor 0.05m～35m ~70m~120m

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Radar water level sensor is a commonly used water level measuring instrument, which uses radar technology to measure the water level of reservoirs, rivers, lakes, dams, deep wells, etc. The Radar water level sensor supplied by Sino-Inst is a 76-81GHz frequency modulated continuous wave (FMCW) radar product, which supports four-wire and two-wire applications. Multiple models, the maximum range of the product can reach 120m, and the blind zone can reach 8 cm. There are PP material and stainless steel material can be customized. Support RS485 Modbus and other signal output.

RFQ

Radar Water Level Sensor Technical Specifications

  • Measuring medium: water
  • Measuring range: 0.05m～35m ~70m~120m
  • Process connection: G1½A / 1½NPT thread / bracket
  • Process temperature: -40～80℃
  • Process pressure: -0.1～0.3 MPa
  • Antenna size: 42mm lens antenna
  • Antenna material: PTFE
  • Accuracy: ±1mm
  • Protection class: IP67
  • Center frequency: 76GHz~81GHz
  • Launch angle: 6°
  • Power supply:
  • Two-wire system/DC24V
  • Four-wire system/DC24V
  • Four-wire system/AC220V
  • Shell: aluminum (with display)
  • Signal output: RS485 Modbus
  • Display: with display/without display

Main advantages:

Based on the self-developed CMOS millimeter wave RF chip, a more compact RF architecture is achieved. Higher signal-to-noise ratio and smaller blind spots.
5GHz working bandwidth enables the product to have higher measurement resolution and measurement accuracy.
The narrowest 3° antenna beam angle, the interference in the installation environment will have less impact on the instrument. The installation is more convenient.
The wavelength is shorter and has better reflection characteristics on solid surfaces. Therefore, no special universal flange is required for aiming.
Support remote debugging and remote upgrade. Reduce waiting time and improve work efficiency.
Support mobile phone Bluetooth debugging. It is convenient for on-site personnel to maintain work

Communication and Debugging

The instrument can be debugged through the LCD on site. It can also be debugged on the PC side with the optional host computer software.
The communication between the radar instrument and the PC is carried out in the following ways:

  1. USB to RS485 serial cable (four-wire system);
  2. USB to TTL serial cable (two-wire system);
  3. USB to Hart-modem (two-wire system) for communication.
  4. Debugging via mobile phone Bluetooth makes on-site debugging safer and more convenient.
  5. 4G network, through the remote module, for remote debugging.

Radar Water Level Sensors Applications

Radar Water Level Sensor Measuring Culverts

A culvert is an engineering structure used to solve the intersection of rivers, streams and other water bodies in road or rail traffic. It works by creating a channel under a body of water that allows the flow of water to flow through it. While maintaining road or rail connectivity. Water level monitoring is crucial in the design and maintenance of culverts.

As a commonly used measuring device, Radar Water Level Sensor has its unique advantages, which can accurately and real-time monitor the water level changes of culverts.

Through the monitoring and analysis of the water level data of the culvert, the water level change of the culvert can be understood in time.

For example, in the rainy season, if the water level of the culvert exceeds a certain safe water level. Engineers can take timely action. Such as increasing the drainage capacity of culverts to ensure smooth and safe traffic.

In addition, water level data can also provide important reference information when maintaining and repairing culverts. Helps engineers determine if culverts have problems or require maintenance.

Application of Radar Water Level Sensor in Shoal

There are several aspects to the application advantages of Radar Water Level Sensor in shoals.

First of all, Radar Water Level Sensor uses microwave signals to measure, which has the characteristics of high precision. It can realize fast and accurate measurement of shoal water level.

Secondly, Radar Water Level Sensor is not affected by weather conditions. Water level measurement can be carried out in various harsh environments, such as rainy and snowy weather, night and so on.

At the same time, the Radar Water Level Sensor is not affected by physical disturbances such as currents, wind and waves. It can realize stable and accurate water level measurement.

Finally, Radar Water Level Sensor is suitable for the measurement of various water environments, and can adapt to various water environments such as shoals, rivers, and lakes.

Radar Water Level Sensor measures river course

As an instrument for measuring river channels, Radar Water Level Sensor uses high-frequency pulse waves for measurement, which has the advantages of high precision and high resolution.

Accurate and real-time monitoring of the water level of the river can be realized, and the precision and accuracy of water level monitoring and control are effectively improved.

In addition, the non-contact measurement method is used to avoid errors and potential safety hazards that may occur in the traditional physical contact measurement method.

At the same time, non-contact measurement can also perform automatic monitoring, which improves the efficiency and accuracy of water level monitoring.

Radar Water Level Sensor measures manhole

As a part of the urban drainage system, the water level measurement of the inspection well faces some particularities and the environment is complex. The inspection well is usually located underground and the environment is complex. There are factors such as high humidity and large temperature changes, which will interfere with the water level measurement.

Large range of water level changes: The range of water level changes in inspection wells is usually large. The water level changes greatly from dry wells to full wells. It is necessary for measuring instruments to have a large measurement range and high precision.

Dirt interference: There may be a lot of dirt in the inspection well, such as sediment, garbage, etc. These dirt will interfere with the water level measuring instrument and affect the measurement accuracy and stability.

Radar Water Level Sensor has great advantages in manhole measurement. It can not only work stably in a complex environment, but also provide accurate and reliable water level data. It provides an important basis for inspection well management and maintenance.

Radar Water Level Sensor measures reservoir water level

A reservoir is an artificially constructed water storage facility, and its water level measurement is very important for the management and operation of the reservoir. Radar Water Level Sensor is widely used in the measurement of reservoir water level due to its stable and reliable features.

First of all, the water level of the reservoir changes slowly. Compared with other water bodies, the water level of the reservoir is usually relatively stable. In this way, the Radar Water Level Sensor can accurately measure the water level and give feedback to the management personnel in time. It is convenient for them to manage the reservoir and scheduling.

Second, the water level of the reservoir varies widely. Radar Water Level Sensor can meet this demand. It has a wide measurement range and can adapt to different water level changes.

In addition, the measurement accuracy of the reservoir water level is high. The Radar Water Level Sensor features high precision to accurately measure water levels.

More Radar Water Level Meters

SIRD-906 Radar Sanitary Level Sensor
SIRD-909 Radar Non-Contact Water Level Sensor
SIRD-908 Radar Water Level Sensor
64-80GHz FMCW Level Radar

FAQ

A radar water sensor works by emitting radio waves that bounce off the surface of the water. The time it takes for the waves to return is measured, and this information is used to calculate the distance to the water surface, thus determining the water level.

A radar sensor for water level measurement is a device that uses radar technology to measure the level of water in a container, tank, or natural body of water. It sends out radar waves and measures their reflection to accurately determine the water’s height.

The accuracy of a water level sensor depends on the technology used and the conditions under which it’s operated. Generally, modern water level sensors can be quite precise, with accuracies ranging from 0.25% to 1% of the full scale.

Radar type level transmitters are known for their high accuracy, often within 1 mm or even better. Their performance can be affected by factors like the material of the container, the type and angle of the radar waves, and environmental conditions, but in general, they are considered highly precise for level measurement.

More Level Measurement Solutions

Radar Liquid Level Sensors

Radar liquid level sensors are special tools that use radio waves to measure how much liquid is in a tank…

As a commonly used water level measuring instrument, Radar Water Level Sensor has important application value in various water level measurements. The application of Radar Water Level Sensor has played a positive role in the operation of water supply sources and hydropower stations. Improved efficiency of water level management.

Sino-Inst is a professional radar level meter supplier. Our Radar Water Level Sensor is a 76-81GHz frequency modulated continuous wave (FMCW) radar product that supports four-wire and two-wire applications. Support customized range 0.05m~35m~70m~120m. If you need to measure water level, you can contact our sales engineers!

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Ultrasonic Sludge level sensor

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Sludge level sensor is also called sludge level transmitter, sludge level detector, Online sludge interface instrument, or sludge blanket level detector. A sludge level sensor is an instrument used to measure the thickness of the mud layer in the liquid.
The sludge level can be expressed as the distance from the water surface (sludge level depth) or the distance from the bottom of the tank (sludge level height). Sludge level sensor is mostly used in the industrial process of solid-liquid separation. Continuously monitor the mud-water interface of sedimentation tanks or special thickening tanks. A sludge level sensor is an instrument commonly used in the sewage treatment industry (wastewater treatment plant) to monitor the sludge level/sludge bed level in the sedimentation tank or thickening tank.

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What is a Sludge level sensor?

Sludge level sensor is an online water quality monitor with a microprocessor. The mud-water interface meter is an industrial online monitoring instrument designed to measure the treatment process of municipal sewage and industrial wastewater.

With the rapid economic development, industrial, agricultural and domestic water use is growing rapidly. More and more sewage is produced, and the problem has become increasingly serious. Therefore, to do a good job in sewage treatment can we ensure the recycling of water resources. In many industrial processes, suspended solids and liquids are separated by sedimentation. This process is usually completed in a sedimentation tank or a special thickening tank. And it is practical, and the mud-water interface must be continuously monitored.

A sludge level sensor is an instrument used to measure the accumulated thickness of sludge at the bottom of the sedimentation tank. It can enable the staff to clearly grasp the amount of sludge at the bottom of the tank at any time. The sludge discharge operation can be carried out in a timely and effective manner.

Ultrasonic Sludge level sensor is designed for long-term reliable operation in industrial and municipal fields. The sensor can work when it is immersed in water 5-10cm. The height of the sludge layer can be determined by ultrasonic emission and echo analysis of suspended solids in the water.

Using ultrasonic to accurately measure the height and thickness of the sludge layer. Effectively grasp the sludge sedimentation characteristics and control the return flow of the sludge. Let the operator make timely evaluations for optimizing the sludge circulation, compensating for the daily fluctuations of wastewater, correcting abnormal state values, and monitoring the separation layer in the pre-concentration tank. It also has a longitudinal profile graph that continuously displays the height of the sludge interface. It is helpful to understand the sludge settlement situation.

Extended reading: ultrasonic sludge level meter

Features of Ultrasonic Sludge level sensor

  • Fully intelligent, multi-function, high measurement performance, strong environmental adaptability;
  • Simultaneous display of multiple parameters, height, output current, time, relay status;
  • Dual 4-20mA transmission output, relay high and low alarm control output, RS485 communication output
  • Various variable output;
  • RS485 upload function;
  • Various installation methods such as plug-in type;
  • The cleaning and maintenance are very simple, and the calibration is performed once every three months;
  • A two-point calibration method is adopted to ensure measurement accuracy;
  • Chinese and English menus are optional;
  • Self-set password: The user can set or modify the password to avoid misoperation caused by unrelated personnel entering;

Specifications of Ultrasonic Sludge level sensor

1. Measuring range: 0.4~10 meters; 0.4-25 meters; or expand according to requirements;

2. Display mode: LCD

3. Unit of measurement: meter

4. Resolution: 0.01m

5. Accuracy: ±0.5 %FS

6. Repeatability: ±0.5%

7. Work rate: ≤3W

8. Ambient temperature: -20~50℃; relative humidity: not more than 90%

9. Analog output: two 4~20mA, load 750Ω

10. Switch output: three-way relay, capacity 250VAC/5A

11. Power supply: AC85~265V±10% or 9~36VDC

Application fields of Sludge level sensor

Sludge level sensor has strong practicability and convenient operation. It is an investment-efficient system for water and sewage treatment plants. Consistent sludge level monitoring data can directly improve the quality of the effluent. It can be widely used in sedimentation tanks of water plants and ore washing plants. Power mortar sedimentation tank. Primary sedimentation tank and secondary sedimentation tank of sewage treatment plant. Sludge interface monitoring fields such as thickening tanks and mortar sedimentation tanks in the power industry.

Read more about: Top 5 Ultrasonic Level Sensor Applications

Sludge level sensor Applications

First settling tank, second settling tank, gravity sedimentation tank;
Oil/asphalt separation tank;
Pulp pool
Waste treatment clarifier;
Beverage water clarification tank;
Mining clarifier;
Brine tank
Mud tank
Any container with a liquid/solid interface.

Extended reading: Case Study: Automatic Sludge Blanket Level Detector

Industry development prospects of Sludge level sensor

With the increasing development of domestic water environment management in recent years. The application range of the sludge interface instrument is still expanding. Under the strong attack of market opportunities, the Sludge level sensor market has ushered in another wave of development.

It is understood that the current monitoring of the mud level of sewage plants on the market mainly relies on manual labor. In addition to traditional visual inspection and water sample collection, there are also sludge interface meters or sludge concentration meters. But still, need a handheld instrument to collect and measure. These monitoring methods either require high manpower. Need real-time participation and poor timeliness. Either the monitoring has blind spots and the accuracy is not high. And it requires 24 hours of manual monitoring in the central control room.

In conclusion, in today’s development of the Internet of Things, machines are used to replace humans to achieve real-time and accurate monitoring. It not only brings great convenience to the development of environmental protection work. It also gives entrepreneurs the opportunity to enter the market. In the future, it is believed that with Sludge level sensor, fast, energy-saving, pollution-free, high selection, and other characteristics, it will serve more fields.

Extended reading: Capacitive water level sensor

Sludge blanket level detector working principle

Ultrasonic mud-water interface measurement uses an ultrasonic sensor installed in the water to emit an ultrasonic pulse to the surface of the mud underwater. This pulse signal is reflected back after encountering the muddy water surface. Can be received by the sensor again.

From the ultrasonic transmission to the re-reception. The time is proportional to the distance from the sensor to the surface of the object being measured.

The meter detects this time. And according to the current temperature (measured by the sensor) underwater sound speed. Calculate the distance from the surface of the measured object to the sensor (that is, the spatial distance). Further, convert the level value.

The empty underwater distance W on the surface of the liquid level is proportional to the travel time T of the sound wave: W=V×T/2 (where V is the speed of the sound wave in water).

The user sets the height H from the probe to the bottom of the pool. The instrument automatically converts the pulse travel time T into the corresponding space distance value W. Then calculate the difference of H minus W is the measured value L.

FAQ

Sludge substances are usually produced in industrial wastewater treatment. It is a mixture of residual organic matter, inorganic particles, bacterial cells, colloids, and other extremely complex substances. According to different sources, sludge can be divided into the following five types:

  1. Primary sedimentation sludge: from primary sedimentation tank.
  2. Wet sludge: from the secondary sedimentation tank after the biofilm process in the secondary sewage treatment.
  3. Residual activated sludge: from the secondary settling tank after the activated sludge method in the secondary sewage treatment.
  4. Digested sludge: from the above three sludge digestion and stabilization processes.
  5. Chemical sludge: it comes from the process of chemical treatment of wastewater.

In addition, sludge can also be divided into organic sludge and inorganic sludge according to the composition of the sludge.

Sludge is a by-product of pollution control technology. This by-product is rich in microorganisms, pathogens, viruses, etc. It has strong pollution properties. If the sludge is improperly disposed of, its pollution spreads through a wide range of ways.

Read more about: Common River Water Level Measurement Methods

The sludge level is the interface between settled down sludge and the above turbid or clear water phase. The sludge level can be given as distance from the water surface (sludge level depth) or as distance to the tank bottom (sludge level height).

In (waste)water treatment and in process control, sludge level is an important parameter. Precise information on sludge level is critical especially in processes regarding phase separation. The WTW sensor can be installed in clear, turbid or even heavily polluted media with high concentrations of suspended solids.

The sludge blanket level can be expressed as the distance from the water surface (sludge level depth) or the distance from the bottom of the tank (sludge level height).

Extended reading: Radar level sensor for solids – Dust solid level measurement

At present, the measurement of sludge mainly uses optical or ultrasonic principles to measure.

  1. Optical sludge interface instrument

Measure the sludge concentration value by using the absorption ratio of sludge to light. Use the cable length to calculate the sludge interface value.

  1. Ultrasonic sludge interface instrument

The distance from the bottom of the pool to the sensor-the distance from the mud layer to the sensor = the sludge interface value

Read more about: The Difference Between Ultrasonic Depth Sensor And Ultrasonic Level Sensor

Calculate the height of the sludge by measuring the distance from the surface of the sensor to the surface of the sludge using ultrasonic waves. Equipped with an advanced ASF (abnormal signal elimination) algorithm, it can be debugged according to the interference situation on the spot. An automatic turning device can be selected according to the site conditions (in the case of a slag scraper). Automatic cleaning devices and wireless transmission devices can meet various complicated working conditions.

Extended reading: Sludge flow meter for sewage treatment return activated sludge system

More Wastewater treatment solutions

Sino-Inst offers over 10 Ultrasonic Sludge level sensors and transmitters for level measurement. 40% for wastewater treatment, 10% for Mud tank, others for more liquid/solid interface.

A wide variety of Ultrasonic Sludge level sensors and transmitters options are available to you, such as free samples, paid samples.

Sino-Inst is a globally recognized supplier and manufacturer of Ultrasonic Sludge level sensors and transmitters instrumentation, located in China.

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64-80GHz FMCW Level Radar

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64-80GHz FMCW Level Radar is a radar sensor for continuous level measurement of liquids. Sino-Inst also launched a radar level sensor operating at 76-81 GHz.

  • FMCW radar operating at 76-81 GHz;
  • Maximum measuring range of 120m and a minimum blind zone of 8cm;
  • 3°antenna beam angle;
  • Suitable for small water tanks or small process accessories in narrow spaces.
  • Good signal focusing ability can be used for containers with many internal installations.
  • Measurement accuracy:±1mm
  • Installation method: Thread or flange, clamps are optional.
  • Anti-dust, anti-steam condensation

Sino-Inst offers a variety of Radar Level Sensors for industrial level measurement. If you have any questions, please contact our sales engineers.

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Radar Level Measurement

Features of 76-81GHz FMCW Level Radar

The LM78xx series is an FMCW radar operating at 76-81 GHz, which has a maximum measuring range of 120m and a minimum blind zone of 8cm. It supports 4-wire and 2-wire applications. Higher operating frequency and shorter wavelengths make it ideal for solid applications, including those with extreme dust and high temperature to + 200℃.

The radar consists of an electronic circuit coupled to a lens antenna and flange for quick and easy positioning.

The main benefits of using 78 GHz over devices using lower frequency are:

  • Based on the self-developed CMOS millimeter wave RF chip, a more compact RF architecture, a higher signal-to-noise ratio, and a smaller blind zone are realized.
  • 5GHz working bandwidth means higher measurement resolution and accuracy.
  • 3°antenna beam angle, so the interference in the environment has less impact on the instrument, and the installation is more convenient.
  • Shorter wavelength yields good reflection properties on sloped solids, so aiming towards material angle of repose is usually not necessary.
  • Support remote debugging and remote upgrading to reduce the cost of field personnel.

Communication and Programming

LM78XX supports 485 bus protocol (4-wire), serial-port (2-wire) protocol, and hart (2-wire) protocol. It is very easy to install and configure via an optional graphical local display interface on a PC. Or you can modify the built-in parameters either locally via the pushbuttons. Or you can use a cell phone to control LM78xx via Bluetooth.

Extended Reading: Case: High Temperature Radar Level Transmitter for Melted Salt-Solar Photovoltaic Power Station

Specifications of 76-81GHz FMCW Level Radar

Frequency76GHz ~ 81GHz,  5GHz FMCW bandwidth
Measuring rangeLM78x0: 0.3 m ~ 60m LM78x1: 0.08m~30m LM78x2: 0.6m ~ 120m
Measurement accuracy±1mm
Beam angle3°/8°
Minimum measured dielectric constant>=2
Power15~28VDC
CommunicationLM782x: MODBUS LM783x: HART/Series
Signal outputLM782x: 4 ~ 20mA or RS-485 LM783x: 4~20mA
Fault output3.8mA, 4mA, 20mA, 21mA, hold
Field operation / programming128 × 64 dot matrix display / 4 buttons PC software Bluetooth
 humidity≤95%RH
EnclosureAluminum alloy, stainless steel
Antenna typeLens antenna/anti-corrosive antenna/flange isolated by quartz
Process temperatureT0:-40~85℃; T1:-40~200℃; T2:-40~500℃; T3:-40~1000℃
Process pressure-0.1~2MPa
Product SizeØ100*270mm
Cable entryM20*1.5
Recommended cablesAWG18 or 0.75mm²
Protection classIP67
Explosion-proof gradeExdiaIICT6
Installation methodThread or flange
Weight2.480Kg/2.995Kg
Packing box size370*270*180mm

Extended reading: FMCW Radar Level Transmitter 120GHz

64-80GHz FMCW Level Radar Applications

Application area:

Special advantages are the small process fittings for small tanks or tight spaces. The very good signal focusing allows use in vessels with many internal installations.

LM78 series FMCW Level Radar Applications

It is suitable for large range, high dust, steam condensation, mixing, narrow installation space, and occasions with high precision and blind zone requirements.

Applicable working conditions:

  • Intermediate silo
  • Warehouse
  • hopper
  • Storage tank
  • Process tank
  • Mixing tank

Extended Reading: Influence of Dielectric Constant on Liquid Level Measurement | Radar-Guided Wave Radar Level Meter

https://www.drurylandetheatre.com/wp-content/uploads/2021/03/76-81GHz-FMCW-Level-Radar-test-1.mp4

The influence of high frequency and low frequency of radar liquid level sensor on measurement

  1. The influence of frequency on measurement

The radar level sensor emits electromagnetic waves through an antenna, and the higher the frequency of the electromagnetic waves. The higher the energy of the electromagnetic wave and the shorter the wavelength, the more obvious the scattering phenomenon. Conversely, the lower the energy, the longer the wavelength, and the energy is not easily absorbed by the gas phase layer.

For an antenna of the same size, a level gauge with a wavelength of 1.2 cm and a frequency of 26 GHz has 6 times higher gain than a level gauge with a wavelength of 3 cm and a frequency of 10 GHz. (Note: Antenna gain is a parameter indicating the degree of concentration of directional antenna radiation).

The received signal diagrams of different frequencies (26-10-6 GHz), the same antenna, dielectric constant, and distance increase are as follows:

The total beam width of the radar level sensor is inversely proportional to the frequency of the device.

Therefore, for an antenna with the same diameter, if the frequency of the radar level sensor is increased, the beam width will be lower than that of a lower frequency device. The narrow beam minimizes the influence of the nozzle, tank wall, and interference.

As shown in the picture (the left side is 6 GHz, the right side is 26 GHz).

At the same time, the measurement range of the radar liquid level sensor is also affected by factors such as frequency, antenna size, the dielectric constant of the liquid, and process conditions.

  1. The application difference between high frequency and low frequency of radar liquid level sensor

When measuring steam, foam, and condensate, choose low-frequency radar first. In most other applications, choose high-frequency radar first for ease of installation.

1) The lower frequency reduces the sensitivity to steam, foam, and antenna contamination. The wave velocity angle of low-frequency radar is wider. It can better deal with the problems of steam, dust, condensation, pollution, and turbulent surfaces.
2) The higher frequency can minimize the impact on the nozzle, tank wall, and interference.

Extended reading: Drop Antenna Radar Tank Level Sensor

Application of 80G radar level sensor in liquid level measurement with stirring and strong steam

The micro-powder business department of a chemical plant has a variety of tanks, with a field measuring a range of 25 meters. There is a stirrer and heating device inside, and there is high steam when feeding.

As shown in the figure below, when the staff opened the observation cover, strong steam could be seen coming out.

A guided wave radar level gauge is selected before the scene. However, guided wave radar is easily affected by factors such as the corrosiveness of the measuring medium and the viscosity of the medium, and the measurement effect is not good.

Extended reading: guided wave radar level sensor advantages and disadvantages

Later, the customer chose the 80G radar level meter, and the historical trend chart after use is as follows. It can be seen that the liquid level of the four 80G radar level gauges installed on-site can be measured well in several loading and unloading processes.

Extended Reading: FMCW Radar for High Temperature Level Sensor

Why do we have to choose an 80G millimeter-wave radar level gauge for liquid level measurement under high steam and stirring conditions? Can the 26G radar level gauge measure?

Explain briefly. The 80G radar level gauge has a high transmission frequency, has good penetration, and is not affected by steam.

The launch angle of 3° can effectively avoid the interference of the stirring blade;

The unique echo tracking algorithm (echo locking function) avoids reading multiple echoes when the material level is high.

However, when the 26G radar level gauge is in a high-steam environment, the radar wave cannot penetrate the steam or the echo is greatly weakened after the radar wave reaches the interface of the medium, and the measurement is unstable;

In addition, the launch angle of the 26G radar level gauge is generally above 20°, so that the radar wave is easily affected by the stirring blade, causing false alarms;

And when the material level is high, there is no internal steam and the range is large, the echo is very strong, and it is easy to read multiple echoes.

Therefore, the 80G radar level gauge can be selected to obtain a good measurement effect for liquid level measurement under high steam and stirring conditions.

Extended reading: Radar Level Meter for Corrosive Liquids

Download Datasheet

64-80GHz FMCW Level Radar datasheetDownload

More Featured Non-Contacting Radar Level Measurement

SIRD-901 Radar Corrosive Liquid Chemical Level Sensor
SIRD-902 Drop Antenna Radar Tank Level Sensor
SIRD-902T Microwave Radar Liquid Level Sensor
SIRD-904 Radar Level Gauge with Parabolic Antenna
SIRD-905 Horn Antenna Radar Tank Level Sensor
SI-FMF11 FMCW Radar Level Transmitter 120GHz
SI-FMF12 Frequency Modulated Continuous Wave Radar Level Sensor
SI-FMF13 FMCW Radar Water Level Sensor

Sino-Inst offers Alternative to 64-80GHz FMCW Level Radars for level measurement.

A wide variety of 64-80GHz FMCW Level Radars options are available to you, such as free samples, paid samples.

Sino-Inst is a globally recognized supplier and manufacturer of radar level measurement instrumentation, located in China.

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Ultrasonic Oil Level Sensor-External Paste-Truck Fuel Tank

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The oil level sensor is very important for monitoring the level of the oil tank/fuel tank. Ultrasonic Oil Level Sensor is mainly used for monitoring the level of truck oil tank. Oil level displays and transmit.

Ultrasonic oil level sensor uses the principle of ultrasonic detection to detect the fuel level of the fuel tank. The fuel volume data is transmitted to the background monitoring system to achieve real-time monitoring of vehicle fuel consumption. Ultrasonic oil level sensor is mainly used in the field of Internet of Vehicles to monitor the change of fuel level in the fuel tank in real-time to achieve fuel level detection. It can be used to prevent fuel stealing, optimize operating costs, optimize driver driving behavior, and assist statistical decision-making. At the same time, this product can also be used in chemical, water conservancy, storage tanks, and other fields that require level detection.

Sino-Inst offers a variety of  Ultrasonic level sensors for level measurement. If you have any questions, please contact our sales engineers.

Request a Quote
Ultrasonic Level Sensors

Features of Ultrasonic Oil Level Sensor

  1. Non-contact measurement. No need to change the shape of the container. No need to polish the surface paint of the container. No need to punch.
  2. Easy to install and maintain. Just install the sensor probe below the outside of the fuel tank. No need to change the original fuel tank measurement system. No need to make holes and changes to the fuel tank. And can guarantee the normal operation of the original automobile fuel gauge.
  3. Prevent the fuel level sensor from being corroded and polluted by the fuel, and can maintain long-term measurement stability;
  4. Metal shell, internal circuit potting treatment, rainproof design, no pressure on outdoor environment.
  5. The external waterproof 3M glue is equipped with a special metal fixing bracket, which is simple to install and firmly fixed.
  6. Wide voltage operation, DC 12～48V power supply, suitable for various vehicles.
  7. RS232/RS485/0～5V voltage analog quantity/TTL-UART multiple output interfaces, compatible with various sensor signal acquisition equipment connections.
  8. High frequency ultrasonic detection, high solid penetration, suitable for containers made of various materials such as metal and plastic.
  9. Strong reliability. It can work normally in harsh environments, moisture-proof, acid-proof, flame-retardant, anti-interference, and intelligent.
  10. The product can be used alone, using the auxiliary display to directly view the data. It can also be used in conjunction with a GPS device to transmit data to the background through the GPS device. Perform data statistics, report analysis and query.

Specifications of Ultrasonic Oil Level Sensor

Parameter itemSpecification Description
Operating VoltageDC12~48V
Working current≤25mA
Measuring range5~150cm
Measurement resolution0.1mm
Explosion-proof gradeIntrinsically safe ExiaⅡCT6 Flameproof ExdⅡCT5
Protection levelIP67 dustproof and waterproof
Operating temperature-20℃~80℃
storage temperature-25℃~85℃
Device interfaceRS232/RS485/0~5V analog
Communication interface parametersCommunication rate 9600bit/s
The thickness of the measured container≤20mm

Remarks:

Ⅰ. Normal temperature and humidity. 1 standard atmosphere. The measured liquid is 0# diesel. For testing other liquids, please specify when ordering.

Ⅱ. The sensor can satisfy 2cm thickness container. 5 meters range requirement. Changes in the measurement range must be notified in advance. Default 5cm~1.

Ⅲ. The sensor RS232/RS485 default automatic output mode, compatible with MODBUS controlled and capacitive stick mode.

Extended reading: Guide to Ultrasonic Level Transmitters

Comparison of Ultrasonic Oil Level Sensor with other Oil Level Sensors

  1. Capacitive type: easy to be affected by oil pollution and cause errors. Can not produce electric sparks. Hole installation.
  2. Resistive type: mechanical measurement. Large error, hysteresis, long-term contact with the sensor. It is easy to be corroded and polluted, which affects the measurement accuracy. The fuel tank must be punched during installation.
  3. Flowmeter type: the oil pipe needs to be cut off, and the fuel filling amount cannot be measured. Only the used amount can be measured. It is not convenient for measurement management.
  4. Reed tube type: measurement output accuracy is low. It is greatly affected by the temperature of the measurement medium and the fluctuation of the power supply voltage. The components are easy to be magnetized. The measurement data is greatly affected by the fluctuation of the oil level and the oil pollution, and cannot be installed and manufactured according to the height of the fuel tank.
  5. Float type: can only be used for the fuzzy indication of the liquid level. It cannot be used for the measurement of the liquid level, the degree of fuel contamination of the film resistor, the power supply voltage, the mechanical structure, the lubricity and other product reasons, and the long-term stability of the output value Greater impact.
  6. Ultrasonic: Use non-contact ultrasonic technology to measure. High measurement accuracy, free from corrosion and pollution, explosion-proof, convenient installation, high stability and wide application.

Explore Oil and Gas Flow Meters

How does an oil level sensor work?

Ultrasonic externally attached oil level sensor uses the principle of ultrasonic echo ranging. The sensor is installed outside the bottom of the fuel tank and sends out an ultrasonic signal from the bottom, which is reflected by the oil surface, and then calculates the height of the liquid level according to time and speed.

At the same time, combined with digital signal processing technology, it overcomes the influence of the container wall and realizes high-precision non-contact measurement of the liquid level in the container, which can meet the requirements of industrial applications in terms of application.

Extended reading: Types of Fuel-Diesel Level Sensors

Ultrasonic Oil Level Sensor Application

The ultrasonic fuel level sensor can be used for various vehicles. Such as logistics vehicles, taxis, buses, passenger vehicles, etc.. It is used to digitally record vehicle fueling and fuel consumption. Prevent fuel theft. Avoid waste of resources. Improve operating efficiency, And improve traffic safety. Strengthen the level of operation and management.

  1. Prevent oil theft: The system can easily read the actual oil volume through the oil volume display screen or the background monitoring terminal. It can effectively control the behavior of stealing oil and falsely issuing fuel bills.
  2. Optimizing operating costs: Through the collection and analysis of statistical monitoring data, the oil volume and mileage at any time can be counted, and the oil volume per kilometer and the fuel cost per kilometer can be calculated. This allows the managers to analyze the economic and fast transportation routes.
  3. Optimize driver’s driving behavior: Real-time monitoring of fuel quantity data can effectively improve the driver’s driving habits and reduce normal fuel consumption.
  4. Strengthen operation management: effective oil quantity data analysis and statistics. Provide scientific decision-making basis for enterprises. Change unreasonable quota oil quantity management indicators based on experience and intuition. Through the statistical analysis of oil quantity, the unreasonable quota oil quantity index can be quickly reduced to a reasonable level. It can save the enterprise’s high oil quantity quota expenditure.

Extended reading: Oil Level Measurement Solutions for the Oil & Gas Industry

https://www.drurylandetheatre.com/wp-content/uploads/2020/11/Externally-attached-ultrasonic-oil-level-sensor.mp4

Extended reading: Diesel fuel tank level gauges & indicators

Ultrasonic Oil Level Sensor Installation Steps

Step 1. Choose the installation location

① When selecting the installation area at the bottom of the fuel tank, try to avoid the oil outlet pipes at both ends of the fuel tank and the barrier position near the oil inlet, and try to choose the ideal installation area at the middle position.

②Clean up the dirt at the installation location with a rag at the selected location. Please do not polish the paint layer at the bottom of the fuel tank before confirming the installation point, so as to avoid the wrong location and waste installation man-hours.

Step 2. Test and confirm the installation point

①Spread the prepared clean water on the sensing area of the probe, and add as much water as possible to ensure that the air on the contact surface between the sensor and the fuel tank is removed, and then the sensor is fixed to the fuel tank to select the installation position.

②Connect the waterproof head of the display board and the waterproof head of the oil level sensor, insert the USB plug of the display board into the pre-prepared mobile power supply, and observe whether the data on the display board is stable to determine whether the selected point is correct.

Step 3. Fix the ultrasonic oil level sensor

① Polish the selected installation point with sandpaper to remove the paint layer to ensure that the installation surface is flat, and clean it again with a rag to ensure that no dirt enters the sensor before installation.

②Use a glue gun to hit the glue into the sensor’s sensing area, and use a toothpick to mix the glue evenly, and then fit it to the fuel tank installation position. The glue will initially solidify in 4-5 minutes at room temperature, and then prepare the wiring.

Ultrasonic Tank Level Sensor-External Mounted

The ultrasonic tank level sensor is a completely non-contact/non-invasive measurement. The principle of ultrasonic (sonar) is used to measure liquid level. Fuel tank level monitoring, display, alarm, etc.

Read more

ultrasonic tank level sensor

Ultrasonic tank level sensor is also often referred to as “ultrasonic water level sensor”, “ultrasonic level detector” or “ultrasonic level transmitter”, etc.

Ultrasonic tank level sensor uses ultrasonic pulse echo to achieve liquid level measurement. Specifically, the transducer (probe) of the ultrasonic tank level sensor emits high-frequency ultrasonic pulses. When it encounters the surface of the liquid level to be measured, the sound waves are reflected Back. Part of the reflected echo is received by a transducer (probe) and converted into an electrical signal.

The user can almost truly know the time of the water level based on the reflected signal. The ultrasonic tank level sensor is one of the most common non-contact liquid level measurement instruments in the industry.

Ultrasonic tank level sensor can be widely used in various atmospheric storage tanks, process tanks, small tanks and small containers, pump lifting stations, waste water storage tanks, etc.;

Due to the flexibility of its design, ultrasonic level gauges can also be used in integrated systems or in place of float switches, conductivity switches and static pressure sensors. It can also be found in integrated applications in fluid control and chemical supply systems.

Extended reading: Capacitance level sensor advantages and disadvantages

Related Products

ULT-200A Ultrasonic fuel tank level sensor
ULT-100 Ultrasonic Level Indicator
Portable Ultrasonic Liquid Level Indicator
HS-2000 Ultrasonic Tank Level Sensor-External Mounted
SIRD-905 Horn Antenna Radar Tank Level Sensor
Alternative to VEGAPULS 64-80GHz FMCW Level Radar
Differential pressure(DP) level transmitte
Remote Seal Differential Pressure Transmitter
SI-302 Anti-corrosive Submersible Level Transmitter

Wireless Level Sensor – LoRa

SI-PCM261 Submersible Pressure Transducer

SIRD-701 Guided Wave Radar Level Sensor

Frequently
Asked
Questions

Contact Us

Ultrasonic liquid level sensor is a digital liquid level meter controlled by microprocessor.

In the measurement, ultrasonic pulses are emitted by a sensor (transducer). The sound wave is reflected by the liquid surface and received by the same sensor. It is converted into an electrical signal by a piezoelectric crystal. Measure the distance to the surface of the liquid.

Due to the non-contact measurement, the measured medium is almost unlimited, and it can be widely used in the measurement of the height of various liquid materials.

In fact, there are many types of oil level sensors. Different types of oil level sensors work differently.

For example, the External PasteUltrasonic Oil Level Sensor mentioned in this article is based on ultrasonic measurement.

There is also a common capacitive oil level sensor. The sensing part of the capacitive oil level sensor is a coaxial container. When the oil enters the container, it causes a change in the capacitance between the sensor housing and the sensing electrode. This variation is converted through the circuit and performs accurate linear and temperature compensation, and outputs a 4-20mA standard signal for the display instrument.

For other types of oil level sensors, please refer to:

Oil Level Measurement Solutions for the Oil & Gas Industry

Of course. The oil level sensor is very important. Whether it is for automobiles or industrial tanks.

Accurate measurement and monitoring of oil level can effectively save production costs and ensure production efficiency.

Read More:

Magnetostrictive Level Gauge Application: Refined Oil Storage Tank

The working principle of the ultrasonic liquid level sensor is:

Ultrasonic transducer (probe) emits high-frequency pulse sound waves, and the surface of the measured level (material) is reflected back. The reflected echo is received by the transducer and converted into an electrical signal. The propagation time of the sound wave is proportional to the distance from the sound wave to the surface of the object.

The relationship between the sound wave transmission distance S and the sound speed C and the sound transmission time T can be expressed by the formula: S=C×T/2.

Image Source： https://www.coulton.com/beginners_guide_to_ultrasonic_level_transmitters.html

The probe part emits ultrasonic waves, which are then reflected by the liquid surface. The probe part is received again. The distance from the probe to the liquid (object) surface is proportional to the elapsed time of the ultrasonic wave:
hb = CT2
Distance [m] = time × speed of sound/2 [m]
The temperature compensation formula of sound velocity:
Ambient sound velocity = 331.5 + 0.6 × temperature

Read more about: How to Choose Explosion Proof Ultrasonic Level Sensor?

Currently, most ultrasonic level sensors on the market have an accuracy of ± 0.5% (standard conditions).

It can already meet the needs of most users.

Different types of oil tank level sensors work based on different measurement principles. Oil tank level sensors measure tank oil level either directly or indirectly.

For detailed classification and working principle of oil tank level sensors, please refer to:

Classification of Oil Level Measurement

Related Blogs

Sino-Inst offers over 10 Ultrasonic Tank Level Sensors for level measurement. About 50% of these are fuel level meters, 40% is the tank level sensor.

A wide variety of Ultrasonic Tank Level Sensor for level measurement options are available to you, such as free samples, paid samples.

Sino-Inst is a globally recognized supplier and manufacturer of Ultrasonic Tank Level measurement instrumentation, located in China.

Request a Quote

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Capacitive Level Sensors

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A capacitive Level Sensor is also called an RF capacitance level meter. Capacitive Level Sensor is a liquid level (level) transmitter for liquid, oil, solid, and interface measurement.

Capacitive Level Sensors can be used for point level detection and continuous level measurement, particularly in liquids. The measuring principle is based on the change of the capacitance in a capacitor. The electrically conductive tank wall and a probe inside of the tank form a capacitor, The capacity changes of which are used to determine the level. This animation shows the measuring principle in conductive liquids and non-conductive liquids. The Capacitive Level Sensor can convert the changes of various levels and the height of the liquid level into standard current signals. Level Sensors can also support wireless transmission, RS485 digital communication transmission, etc.

Featured Capacitive Level Sensors

RF Admittance Level Sensor
Capacitance Level Transmitter
807 Low Temperature Liquid Level Sensor

Extended reading: ​Solid flow meter | For bulk solids-powder-soybean-cement 

Capacitive level sensor working principle

The capacitive level sensor is based on the change of capacitance to perform liquid/level measurement. The level gauge electrode and the container form two electrodes of a capacitor. The capacitance value varies with the container.

The level of the material medium changes and changes, and is converted to the corresponding level output signal.

A basic requirement for measuring liquid/level with a capacitance level meter is the relative medium of the measured medium.

The electrical constant (the ratio of the dielectric constant of the measured medium to the air) should not change during the measurement.

Endress+Hauser has a good explanation video about Measuring Principle Capacitance. Let’s look together.

Video source: https://www.youtube.com/watch?v=MPCUDVp0WZc

If you need to purchase a liquid level gauge for CO2 Cylinders, you may like:

CO2 Cylinder | Portable Liquid Level Gauge

Procurement Guide: Ultrasonic liquid level sensors

Featured Level Sensors

  • HS-ULC-Pro Ultrasonic Non-contact Liquid Level Controller
  • HS-2000 Ultrasonic Tank Level Sensor-External Mounted
  • SI-FMF12 Frequency Modulated Continuous Wave Radar Level Sensor
  • SIRD-702 GWR Corrosive Liquid Chemical Level Sensor
  • LD series Rigid Probe Magnetostrictive Level Transmitter
  • SMT3151LT-Differential-pressureDP-level-transmitter
  • LR series Integral flange Magnetostrictive level sensor
  • SI-U04 Magnetic Float Level Sensor-Reed Switch

Read more about: Factors To Consider When Selecting A Capacitive Level Sensor

Sino-Inst offers over 10 Capacitive Level Sensors for level measurement. About 50% of these are RF level meters, 40% is the tank level sensor.

A wide variety of Capacitive Level Sensors are available to you, such as free samples, paid samples.

Sino-Inst is a globally recognized supplier and manufacturer of Capacitive Level measurement instrumentation, located in China.

Request a Quote

Please enable JavaScript in your browser to submit the form

RF Admittance Level Sensor

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RF Admittance Level Sensor is developed from radio frequency capacitance. More accurate and more applicable continuous level measurement.

RF Admittance Level Sensor is a continuous level measurement product designed based on the principle of radio frequency admittance. The product has the advantages of high stability, high sensitivity, and wide range of applications. Compared with the traditional capacitive level sensor, the RF Admittance Level Sensor adopts a modular design. The meaning of admittance is the reciprocal of the impedance in electricity. It is composed of resistive, capacitive and inductive components. The radio frequency is high Frequency radio spectrum. So radio frequency admittance can be understood as measuring admittance with high frequency radio waves. When the instrument is working, the sensor and the tank wall and the measured medium form an admittance value. When the height of the medium changes, the admittance value changes accordingly. The detection circuit converts the measured admittance value into a level signal output.

Sino-Inst offers a variety of  Capacitance Level Transmitters for level measurement. If you have any questions, please contact our sales engineers.

Request a Quote
Capacitive Level Sensing

Features of RF Admittance Level Sensor

The radio frequency admittance level meter has the following advantages:

  • Anti-hanging material: unique independent measurement impedance and capacitive reactance design improve the anti-hanging ability
  • Strong adaptability: Probe temperature range: -100 ℃…500 ℃
  • Range: The minimum measurement range can reach a few centimeters and the maximum measurement range can reach hundreds of meters
  • Interface measurement: suitable for measuring oil-water interface and gas-liquid interface
  • Non-sticky: suitable for measuring viscous materials, the probe has no hanging material
  • High stability: stable and reliable output, resistant to fly ash, blanking, moisture, crystallization, waxing
  • Maintenance-free: no movement, no wear parts, no need for frequent cleaning, maintenance, and debugging 　　
  • Better measurement effect for materials such as powder particles;
  • The process connection size is small, which is convenient for hole installation;
  • It has better adaptability to the measurement of small tanks and special tanks;
  • The measurement blind area is small, which maximizes the measurement range;
  • Good directionality, especially special tanks and special-shaped tanks, with low transmission loss and many measurable media.

RF Admittance Level Sensor Probe Types

RF Admittance Level Sensor-16-Insulated Hard Rod

Probe type: insulated hard rod
Process temperature: -100…200℃
Process pressure: -0.1…4.0MPa
Output mode: 4～20mA
Process connection: 3/4″BSPT threaded installation (standard)/flange installation (optional)
Explosion-proof grade: ExiallCT4 (optional)
Typical application: corrosive/conductive liquid, viscous liquid, can be installed separately

RF Admittance Level Sensor-17-Insulated Flexible Cable

Probe type: insulated flexible cable
Process temperature: -40…140℃
Process pressure: -0.1…4.0MPa
Output mode: 4～20mA
Process connection: 3/4″BSPT threaded installation (standard)/flange installation (optional)
Explosion-proof grade: ExiallCT4 (optional)
Typical application: conductive liquid, conductive solid powder, insulated flexible cable, can be installed separately

RF Admittance Level Sensor-18-Non-insulated Flexible Cable

Probe type: non-insulated flexible cable
Process temperature: -100…200℃
Process pressure: -0.1…6.3MPa
Output mode: 4～20mA
Process connection: 1″BSPT thread installation (standard)/flange installation (optional)
Explosion-proof grade: ExiallCT4 (optional)
Typical application: insulating solid, insulating liquid non-insulated flexible cable, can be installed separately

RF Admittance Level Sensor-19-Insulated flexible cable

Probe type: insulated flexible cable
Process temperature: -100…200℃
Process pressure: -0.1…4.0MPa
Output mode: 4～20mA
Process connection: 3/4″BSPT threaded installation (standard)/flange installation (optional)
Explosion-proof grade: ExiallCT4 (optional)
Typical application: conductive liquid, interface, can be installed separately

RF Admittance Level Sensor-20-Flexible Cable

Probe type: flexible cable
Process temperature: -50…140°C
Process pressure: -0.1…1.6MPa
Output mode: 4～20mA
Process connection: 3/4″BSPT threaded installation (standard)/flange installation (optional)
Explosion-proof grade: ExiallCT4 (optional)
Typical application: deep well, super long range, can be installed separately

RF Admittance Level Sensor-21-Hard Rod Tube

Probe type: barrel type hard rod
Process temperature: -100…200℃
Process pressure: -0.1…6.3MPa
Output mode: 4～20mA
Process connection: 1 1/2″BSPT threaded installation (standard)/flange installation (optional)
Explosion-proof grade: ExiallCT4 (optional)
Typical application: low dielectric constant liquid, can be installed separately

RF Admittance Level Sensor-22-Double insulated hard rod

Probe type: double rod insulated hard rod
Process temperature: -100…260℃
Process pressure: -0.1…4.0MPa
Output mode: 4～20mA
Process connection: 3/4″BSPT threaded installation (standard)/flange installation (optional)
Explosion-proof grade: ExiallCT4 (optional)
Typical application: strong corrosive liquid with reference electrode, conductive liquid, interface, can be installed separately

RF Admittance Level Sensor-23-Insulated hard rod

Probe type: insulated hard rod
Process temperature: -100…200℃
Process pressure: -0.1…6.3MPa
Output mode: 4～20mA
Process connection: 1″BSPT thread installation (standard)/flange installation (optional)
Explosion-proof grade: ExiallCT4 (optional)
Typical applications: interface, power off, strong stirring occasions, can be installed separately

RF Admittance Level Sensor-24-High temperature flexible cable

Probe type: insulated flexible cable
Process temperature: -50…800 ℃
Process pressure: -0.1…4.0MPa
Output mode: 4～20mA
Process connection: 3/4″BSPT threaded installation (standard)/flange installation (optional)
Explosion-proof grade: ExiallCT4 (optional)
Typical application: high temperature insulating solid, can be installed separately

Specifications of RF Admittance Level Sensor

Power supply:13VDC～35VDC
Output:4～20mA
Environment temperature:-40℃～70℃
Medium temperature:-100℃～800℃
Linearity:0.50%
Repeatability:0.10%
Delay:1～30s adjustable
Spark protection:built-in spark protection circuit (to sensor)
Electrical interface:M20*1.5
Cable:The special connection cable between the split electronic unit and the sensor is standard 5m, the longest is 50m
Process connection:BSPT threaded installation (standard)/flange installation (optional)
Shell protection:IP66
Certification:ExiaIICT4

Read more about: Factors To Consider When Selecting A Capacitive Level Sensor

RF Admittance Level Sensor’s Applications

  1. Power plants: coal piles, raw coal bins, fuel bins, reservoirs, exhaust gas purification tanks, bin pumps, ash storage, fuel tanks, etc.
  2. Chemical industry: distillation tower, raw material and intermediate silo, reaction tank, ammonia tank, toxic liquid tank, solid silo, separator, etc.
  3. Petrochemical: oil pipelines, distillation towers, concentration tanks, liquefied gas tanks, ammonia tanks, steam drums, oil refinery oil depots, electrical desorption interfaces, asphalt tanks, etc.
  4. Water and water treatment: reservoirs, sewage tanks, water treatment tanks, sedimentation tanks, digestion towers, gas pipelines, deep wells, drinking water networks, etc.
  5. Cement: Stone silos, raw meal silos, cement silos, coal powder silos, slag storage silos, etc.
  6. Metallurgy: ore silo, ore crusher, raw material silo, auxiliary silo, blast furnace, alumina powder silo, electrolytic cell buffer tank, etc.
  7. Oilfield: crude oil or product oil storage tanks, three-phase separators, sedimentation tanks, sewage tanks (pools) and oil-water interfaces, drilling mud tanks, etc.
  8. Papermaking: raw material warehouse, storage tower, drying drum, etc.
  9. Others: quarry, food, pharmaceutical, environmental protection, shipbuilding and other industries

Extended reading: GWR Solid Level Sensor-for Cement silo-Ash powder measure

RF Admittance Level Sensor Working Principle

RF Admittance Level Sensor works based on radio frequency admittance level control technology. Radio frequency admittance level control technology is a development from capacitive level control technology. The material to which the sensor adheres is called hanging material. The anti-hanging material performance is better, the work is more reliable, and the measurement is more accurate. Level control technology with wider applicability. The meaning of “admittance” in “radio frequency admittance” is the reciprocal of impedance in electricity. It is composed of resistive, capacitive and perceptual components. “Radio frequency” means high frequency, so radio frequency admittance technology can be understood as a method of measuring admittance with high frequency current.

The important difference between point radio frequency admittance technology and capacitance technology is the use of three-terminal technology and the diversity of measurement parameters. The measurement signal at the center end of the circuit unit is connected with the center line of the coaxial cable. Then connect to the center end of the sensor.

At the same time, the shielding layer of the coaxial cable is suspended on a level that is very small and very stable, but has the same potential, the same phase and the same frequency as the measurement signal, but has no direct electrical relationship, that is, isolated from each other. The effect is equivalent to that the measured signal passes through a non-inverting amplifier with a gain of “1” and a strong drive capability. The output is connected to the shield of the coaxial cable. Then connect to the shielding layer of the sensor. The ground wire is another independent wire in the cable.

Because of the above-mentioned relationship between the center line of the coaxial cable and the outer shield, there is no potential difference between the two. Therefore, no current flows, that is, no current leaks from the center line. It is equivalent to no capacitance between the two or the capacitance is equal to zero. Therefore, the temperature effect of the cable and the installation of capacitors will not have an impact.

For the problem of hanging material on the sensor. Adopt a new sensor structure, five-layer concentric structure.

Sensor structure: The innermost layer is the center probe, the middle is the shielding layer, and the outermost is the grounded mounting thread, which is isolated by an insulating layer. As with the coaxial cable, there is no potential difference between the center probe and the shield. Even if the impedance of the hanging material on the sensor is small, no current will flow.

The electronic instrument measures only the current from the center of the sensor to the opposite tank wall (ground). Because the shielding layer can prevent the current from flowing back along the sensor to the container wall. Therefore, the ground current can only pass through the measured material to the opposite container wall through the end of the sensor.

That is, U center probe = U shielding layer, I center probe pair shielding layer = (U center probe-U shielding layer) × YL=0.

Although there is a potential difference between the shielding layer and the container wall, current flows between the two. But the current is not measured and does not affect the measurement result. In this way, the measuring terminal is protected from the influence of hanging materials. Only when the material in the container actually opens up and contacts the central probe, the measured current can be formed between the central probe and the ground through the measured material. The instrument detects this current and generates an effective output signal.

Radio frequency admittance technology introduces measurement parameters other than capacitance, especially resistance parameters. The signal-to-noise ratio of the radio frequency admittance level meter measurement signal increases. The resolution, accuracy and reliability of the radio frequency admittance level gauge are greatly improved. The diversity of measurement parameters also greatly expands the reliable application fields of radio frequency admittance level gauges.

The radio frequency admittance level gauge sensor can choose a variety of materials. Can be installed integrally or separately. Used for limit control and alarm. Welcome to contact Sino-Inst for detailed information.

Extended reading: GWR Solid Level Sensor-Cement silo-Ash powder measure

Application Range of Various Level Sensors

There are many types of level gauges. There are heavy hammer level gauges, resistance-rotation level gauges, radio frequency admittance level gauges, diaphragm level gauges, tuning fork level gauges, vibrating rod level gauges.

They each have their own advantages and are suitable for different working conditions.

Rotary resistance level gauge

The anti-rotation level gauge can be used for the measurement of solid particles and dust. Mainly used in feed, silica, stones, spherical particles, wood chips, calcium powder, rubber, metal, limestone, grain, foundry sand, sawdust, coal powder, resin, raw leather, peanuts, clay and other materials measuring.

Radio frequency admittance level gauge

RF admittance level gauge products are widely used. Several typical occasions are as follows: the measurement of materials such as chemicals, plastics, films, feed, grain rubber medicines, liquid waste water, sand, food slurry cement, powder coating/clothing coal, granular solid oil and paper pulp.

Diaphragm level gauge

The diaphragm level gauge can be installed outside the container, whether it is installation, maintenance, equipment replacement or sensitivity adjustment. In practical applications, it is not recommended to use in the environment where the material is extremely light, viscous or large particles

Tuning fork level gauge

A dual-purpose level switch with an intelligent circuit for the tuning fork level gauge. Suitable for almost all liquids, light, easy-flowing solids

Vibrating rod level gauge

The vibrating rod level gauge can be used to monitor powder, grain or bulk materials (the diameter does not exceed 5-10cm). The density of the material must be greater than 0.05KG/DM3.

If it is lower than this density, the internal friction of the material will not be enough to weaken the amplitude of the vibration switch. This kind of vibrating level switch can be widely used in the monitoring of coal, cement, limestone, grain, sugar, fly powder and other materials.

Featured Level Sensors

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Radio frequency admittance is a new type of level control technology with wider applicability developed from capacitive type. It is an upgrade of capacitive level technology. The so-called radio frequency admittance, the meaning of admittance is the reciprocal of impedance in electricity. It is composed of resistive components, capacitive components, and inductive components. The radio frequency is the high-frequency radio spectrum. So the radio frequency admittance can be understood as using high frequency Radio wave measurement admittance.
When the meter is working, the sensor of the meter forms an admittance value with the tank wall and the measured medium. When the level changes, the admittance value changes accordingly. The circuit unit converts the measured admittance value into a level signal output to realize level measurement.

RF level sensor adopts advanced RF admittance technology. It overcomes the defect that the capacitive level meter cannot eliminate the influence of the conductive hanging material.

It is not affected by water vapor, dust or condensation, and has the advantages of stable and reliable long-term operation, high sensitivity, good linearity, high temperature resistance, and high pressure resistance.

It can be used for liquid level (level) measurement of liquid, oil and solid measurement, without moving parts.

The RF type level switch realizes the level measurement and control by sensing the change of reactance (capacitive reactance and impedance) between it and the tank body.

The internal electronic unit, the reactance between the probe measuring pole and the empty tank together form a balanced bridge circuit and generate a stable oscillating signal.

When the measured medium covers the probe measuring pole, the reactance change between the probe measuring pole and the tank will cause the bridge circuit to be unbalanced and stop generating oscillating signals. The post-stage circuit detects this change and outputs an alarm signal.

The oscillating signal is applied as a radio frequency signal at the same time as the probe’s measuring pole. It is also sent to the protection pole of the probe after passing through a 1:1 voltage follower. The radio frequency signals of the measuring electrode and the protection electrode have the same potential, the same phase, the same frequency and are isolated from each other.

When the probe is hung with material, there is no potential difference between the measuring electrode and the guard electrode to form electrical isolation to ensure that the signal change of the guard electrode does not affect the detection. The change of the reactance on the probe measuring pole can only be determined by the material between the probe measuring pole and the tank. So that the hanging material on the probe will not affect the normal detection.

Types of Level Transmitters:
Level measurement transmitters are of seven types. Each type of transmitter works in a different way, and makes it useful for different types of processes.
Capacitance Level Transmitters
Hydrostatic Level Transmitters
Magnetic Level Transmitters
Radar Fill Level Transmitters
MUltrasonic Level Transmitter
Guided Microwave Level Transmitters
Hydrostatic level transmitters

The main function of the liquid level sensor is to detect the liquid level. The functions that can be implemented include water shortage protection, no water alarm, waterproof overflow, high liquid level reminder, etc.
The liquid level sensor is used to detect the liquid level, and it is determined that the liquid level needs to be controlled at the position. Then the liquid level sensor is installed in the corresponding position.
For example, the liquid level at the bottom of the container needs to be measured, and a signal reminder needs to be given when no liquid is detected.
Then when the container is in a liquid state, the sensor works normally. When the liquid level drops to a low level, the liquid level sensor will give a signal reminder or alarm when it detects this industrial control change.

Related Blogs

Sino-Inst offers over 10 RF Admittance Level Sensors for level measurement. About 50% of these are RF level meters, 40% is the tank level sensor.

A wide variety of RF Admittance Level Sensors are available to you, such as free samples, paid samples.

Sino-Inst is a globally recognized supplier and manufacturer of RF Admittance Level Sensor instrumentation, located in China.