Updated April 20, 2026 by Sino-Inst Engineering Team

Choosing an ammonia flow meter starts with one question: is the NH3 liquid, gas, or switching between both? Each phase demands a different meter technology. Anhydrous liquid ammonia pressurized to 10 bar behaves nothing like gaseous ammonia in a refrigeration vapor line, and treating them as “the same fluid” is the number one sizing mistake we see on ammonia projects.

Contents

• What is an ammonia flow meter?
• Gas vs liquid ammonia — why phase decides the meter
• Meter types that work on ammonia service
• How to choose an ammonia flow meter
• Where ammonia flow meters are used
• Featured ammonia-rated flow meters
• FAQ

What is an ammonia flow meter?

An ammonia flow meter is an industrial flow measurement device designed to handle the physical and chemical properties of NH3: corrosive to copper and brass, toxic above 25 ppm exposure, and phase-changing between vapor and liquid over a narrow temperature and pressure window. The meter must be built in NH3-compatible materials (316L stainless steel, PTFE, Viton), rated for the working pressure (typically 10–20 bar for liquid, 2–4 bar for vapor), and sized for the expected phase.

Ammonia is used in fertilizer production, industrial refrigeration, and increasingly in chemical energy storage. Every one of these applications needs a flow meter that survives NH3 and reports mass or volume to better than ±1% for process control and better than ±0.5% for custody transfer.

Gas vs liquid ammonia — why phase decides the meter

Liquid ammonia has a density of about 682 kg/m³ at 0 °C; gaseous ammonia at atmospheric pressure is 0.77 kg/m³ — roughly 900 times less dense. Volumetric meters read volume, not mass, and the same meter on two different phases will give two radically different mass readings at the same 4–20 mA output.

Coriolis wins on pure ammonia because it measures mass directly. Phase does not matter — 1 kg of liquid NH3 reads the same as 1 kg of gaseous NH3 as long as the flow is single-phase across the tubes. The cost is higher upfront, but you buy out the density compensation problem entirely.

For aqueous ammonia (ammonium hydroxide), the conductivity rises to 5–50 mS/cm and a PFA-lined magnetic flow meter becomes the right answer. Anhydrous ammonia has essentially zero conductivity, which is why magmeters do not work on pure NH3.

Meter types that work on ammonia service

Coriolis mass flow meter

Direct mass reading, phase-independent, ±0.1% accuracy on liquid NH3. The default choice for any high-accuracy ammonia service — custody transfer, fertilizer blending, refrigerant charging. 316L wetted parts as standard. Cost is 3–5× a comparable volumetric meter. For ammonia density verification downstream, see our liquid ammonia density measurement guide.

Thermal mass flow meter

Best on clean, dry gaseous NH3 at steady pressure. The meter measures heat transfer between two RTDs, which is density-sensitive, so sudden pressure changes require recalibration. Accuracy is ±1% of reading for well-controlled flow. Not suitable for two-phase or wet refrigerant vapor.

Turbine flow meter

Works on single-phase liquid anhydrous ammonia with a strainer ahead. Accuracy is ±0.5% of reading across 10:1 turndown. Stainless steel body and PTFE bearings are required; brass and bronze are not ammonia-compatible. Cheaper than Coriolis; a good choice for OEM skids and intermediate-accuracy applications.

Vortex flow meter

Handles high-pressure gaseous ammonia in superheated lines. Needs external pressure and temperature compensation to convert volume to mass. Minimum Reynolds number of 10,000 means low flows drop out. Rugged, no moving parts, good for 250+ °C service where Coriolis is not rated.

Differential-pressure (V-cone, orifice, Verabar)

Large-DN gaseous ammonia lines in fertilizer plants often use DP elements. V-cone handles dirty gas better than orifice. Accuracy ±1–2% of full scale; turndown limited to 4:1 without a smart DP transmitter. Needs separate pressure and temperature inputs to compute mass.

Magnetic (electromagnetic)

Does not work on anhydrous NH3 (too low conductivity). Works on aqueous ammonia (ammonium hydroxide), aqueous urea, and urea-ammonia blends used in SCR DEF systems. PFA lining is mandatory for corrosion resistance.

How to choose an ammonia flow meter

Work through these decisions in order. Skipping even one leads to a meter that does not fit the service.

1. Phase: liquid, vapor, two-phase, or aqueous? Each demands a different meter category.
2. Accuracy needed: custody transfer (±0.2%) drives you to Coriolis. Process control (±1%) opens the door to turbine, thermal, or vortex.
3. Pressure and temperature: ammonia refrigeration runs at −40 °C; urea-ammonia plants run at 160 °C. Check the meter temperature spec carefully.
4. Line size and flow range: match meter to flow velocity, not pipe DN. See 6-inch DN150 flow meter selection for guidance on larger lines.
5. Materials: 316L stainless steel is standard. No copper, no brass, no aluminum in wetted parts. PTFE and Viton for seals. Soft seals for ammonia refrigeration must be certified for NH3 service (EPDM is acceptable; Buna-N is not).
6. Hazardous area rating: ammonia is classified Group IIA in IEC, so most industrial certifications cover it. Confirm ATEX or IECEx zone rating on the nameplate.
7. Output: 4–20 mA for standalone instruments, Modbus RS-485 for skid integration, HART for DCS diagnostics. For flow totalization, the meter must support pulse output or Modbus totalizer.

Related service: if you also need to measure ammonia gas concentration or leak detection, see the gas analyzers in our industrial gas flow measurement range — same housing platform, different sensor.

Where ammonia flow meters are used

• Fertilizer production: urea, ammonium nitrate, and compound fertilizer plants meter anhydrous ammonia and process gas.
• Industrial refrigeration: NH3 as refrigerant in cold storage, food processing, ice rinks, and district cooling.
• SCR NOx reduction: aqueous ammonia or urea-ammonia injection into flue gas for power plant emission control.
• Agricultural direct application: anhydrous NH3 injection into soil as a nitrogen source; high-flow, seasonal demand.
• Chemical energy storage: emerging use of green ammonia as hydrogen carrier; high-purity, custody-transfer metering.
• Semiconductor manufacturing: precursor gas flow control at low flow rates; thermal mass meters dominate.

Featured ammonia-rated flow meters

Triangle Coriolis Mass Flowmeter

Direct mass measurement for liquid anhydrous ammonia and custody-transfer duty. ±0.1% accuracy, 316L wetted parts, −50 °C to +150 °C. Phase-independent — handles occasional vapor flash without losing signal.

V-Cone Flow Meter

Low-maintenance DP element for gaseous NH3 in large-DN fertilizer and SCR lines. ±1% accuracy, excellent turn-down with smart DP transmitter, no moving parts, tolerates dirty gas.

Magnetic Stainless Steel Flow Meter

PFA-lined electromagnetic meter for aqueous ammonia (NH4OH) and urea-ammonia SCR injection. ±0.2% of rate, 100:1 turndown, no moving parts, no straight-run penalty past DN50.

FAQ

What flow meter is used for anhydrous ammonia?

A Coriolis mass flow meter is the standard choice for anhydrous liquid ammonia. It reads mass directly, is unaffected by phase flashing, and uses 316L stainless steel — fully compatible with NH3. For lower accuracy or OEM cost points, a stainless steel turbine with PTFE bearings is a valid alternative.

Why can’t a magnetic flow meter measure anhydrous NH3?

Magnetic flow meters need a conductivity above about 5 µS/cm to generate a signal. Anhydrous ammonia has essentially zero conductivity. Aqueous ammonia is highly conductive and a magmeter works perfectly on NH4OH, but not on pure NH3.

How do you meter ammonia gas flow?

For dry, single-phase NH3 vapor, use a thermal mass flow meter or a Coriolis. For large lines in fertilizer plants, a V-cone or Verabar DP element with pressure and temperature compensation computes mass from volume. Vortex meters work above Reynolds 10,000 but require external compensation.

What materials are compatible with ammonia?

316L stainless steel, PTFE, Viton, EPDM, and some grades of polypropylene are compatible with ammonia. Copper, brass, bronze, zinc, and aluminum all react with NH3 and must not be used in wetted parts. Seals should be EPDM or PTFE, never Buna-N.

What is the accuracy of an ammonia Coriolis flow meter?

Typical Coriolis accuracy on liquid ammonia is ±0.1% of reading over 10:1 turndown. For custody-transfer installations, calibration to ±0.05% is available by the manufacturer. Pressure and temperature do not affect accuracy because Coriolis reads mass directly.

Can one flow meter handle both liquid and gas ammonia?

Only Coriolis can. Because Coriolis measures mass, a calibrated meter reads correctly whether the tube is full of liquid or gas, as long as flow is single-phase through the measuring section. Volumetric meters (turbine, vortex, thermal) lose accuracy immediately on phase change.

Looking for a quote on an NH3 flow meter? Send your phase, pressure, temperature, flow range, and pipe size. Our engineering team will match a meter, confirm materials compatibility, and issue a specification sheet within 24 hours.

Request a Quote

KimGuo11

Wu Peng, born in 1980, is a highly respected and accomplished male engineer with extensive experience in the field of automation. With over 20 years of industry experience, Wu has made significant contributions to both academia and engineering projects.

Throughout his career, Wu Peng has participated in numerous national and international engineering projects. Some of his most notable projects include the development of an intelligent control system for oil refineries, the design of a cutting-edge distributed control system for petrochemical plants, and the optimization of control algorithms for natural gas pipelines.

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Updated April 20, 2026 by Sino-Inst Engineering Team

Metering steam is expensive. Temperatures above 180 °C, saturated vs superheated corrections, and dropout from wet steam all push cost and error up. One pound of condensate equals one pound of steam — so for billing, boiler efficiency, and sub-metering, measuring the condensate is almost always the better call. The catch: you have to pick a meter that matches your return-line topology (pumped, gravity, flash), or you will chase accuracy forever.

Contents

• Why measure condensate instead of steam?
• Pumped vs gravity return — pick before you pick the meter
• Condensate flow meter types compared
• Sizing and installation rules
• Featured flow meters for condensate service
• FAQ

Why measure condensate instead of steam?

Measuring condensate is cheaper because you are metering a cool, single-phase liquid instead of a two-phase vapor at 8–40 bar. A volumetric liquid meter costs a fraction of a wet-steam-compensated vortex installation, and it does not need pressure or temperature compensation to stay within ±2% accuracy.

• Lower install cost: no steam-rated flanges, no insulated impulse lines.
• Lower measurement error: liquid flow is stable; steam flow swings with load.
• Easier billing: condensate volume × density gives mass in kg. Mass balances against boiler output.
• No wet-steam correction: vortex or orifice on steam requires a dryness factor; condensate has none of that.

The exception is branched distribution where you need flow per user. In that case steam-side metering wins, because one condensate line usually lumps multiple users together. For plant-level and building-level accounting, condensate metering is the standard.

Pumped vs gravity return — pick before you pick the meter

Return-line topology decides which meters are even candidates. Gravity returns run half-full with entrained flash steam; pumped returns run full with a stable liquid head. Put the wrong meter on the wrong line and you will read 30–50% low.

Install the meter on the pumped side of a condensate receiver whenever possible. Put it on the vertical rise right after the pump so the pipe stays full through the measuring section. If you only have a gravity line, switch meter category — do not try to force a clamp-on ultrasonic onto a half-full horizontal pipe. For the straight-run requirements behind this rule, see our upstream and downstream pipe guide.

Condensate flow meter types compared

Five technologies cover 95% of real installations. Here is how they stack up on the factors that actually matter for condensate — turndown, temperature rating, and cost.

For pure water condensate below 0.5 µS/cm (distilled or demineralized), a magnetic flow meter will not work — water has to conduct. Use a vortex or Coriolis on that service. For pumped returns at 80–120 °C in a typical plant, a PFA-lined magmeter is the default and hits ±0.2% without any temperature compensation.

Sizing and installation rules

Undersize your meter by one line size. Most condensate lines are sized for steam flow and run at 5–15% of liquid capacity, which drops velocity below the meter’s minimum range. A DN100 condensate line commonly needs a DN50 or DN65 meter with a reducer.

1. Check velocity: target 1–3 m/s at normal flow. Below 0.5 m/s, meter accuracy collapses.
2. Match the meter DN to the velocity band, not the pipe DN. Add concentric reducers if needed.
3. Install after the condensate pump, never before. The suction side is two-phase and cavitating.
4. Mount on a vertical rise with flow upward. That guarantees full-pipe operation and flushes out flash steam.
5. Respect straight run: 10D upstream, 5D downstream for most meters. Vortex and Coriolis are more forgiving; DP types are stricter. Our straight-length requirements guide covers each meter type in detail.
6. Add a strainer ahead of turbine or DP meters. Scale and pipe rust destroy turbine bearings within months in condensate service.
7. Calibrate with the operating fluid where accuracy matters. Factory water calibration transfers well to condensate, but high-temperature service can shift span by 1–2%.

Commissioning note: always zero the meter with a positive shutoff. Flash steam moving past an “off” meter on a shared header will read as flow. For DP-type meters, see our DP transmitter installation guide for impulse-line slope and condensate pot placement.

Featured flow meters for condensate service

Industrial Magmeter Flow Meter

PFA-lined electromagnetic flow meter for pumped condensate returns. ±0.2% of rate, 100:1 turndown, up to 180 °C. Default choice for plant-level condensate sub-metering.

Verabar Averaging Pitot Flow Meter

Insertion-type DP meter for large-DN boiler feedwater and high-pressure condensate headers. Hot-tap installable, ±1% accuracy, up to 400 °C. Low permanent pressure loss.

Liquid Turbine Flow Meter

Cost-efficient turbine meter for clean pumped condensate below 150 °C. Pulse or 4–20 mA output, ±0.5% of reading. Pair with an upstream strainer.

FAQ

What is the best flow meter for steam condensate?

A PFA-lined magnetic flow meter is the default for pumped condensate above 5 µS/cm conductivity. It gives ±0.2% accuracy with no moving parts. For pure demin water or custody transfer, switch to Coriolis. For gravity returns, use a gravity condensate meter — not an inline meter.

Can you use a vortex meter on condensate?

Yes, on pumped returns and boiler feedwater. Vortex meters handle 240 °C without temperature compensation and survive small scale particles. They need a minimum Reynolds number of about 10,000, so very low flows drop out of range. See our breakdown of flow meter element types for detail.

How much cheaper is condensate metering vs steam metering?

For DN50–DN150, a condensate magmeter costs roughly 30–50% of a compensated steam vortex package. Installation is also cheaper — no insulated impulse lines, no temperature transmitter, no density compensation flow computer. Payback vs steam metering is often under 12 months on plant sub-metering projects.

Where should a condensate flow meter be installed?

On the pumped discharge side, on a vertical rise, with 10D upstream and 5D downstream straight pipe. Downstream of the condensate receiver tank, upstream of any control valve or check valve. Never on a gravity line unless you are using a meter specifically designed for gravity flow.

Need help sizing a condensate meter for your plant? Our engineers have commissioned condensate metering across boiler houses, district heating networks, and food & beverage plants. Send your line size, flow range, and pressure, and we will come back with a specified meter and a quote.

Request a Quote

KimGuo11

Wu Peng, born in 1980, is a highly respected and accomplished male engineer with extensive experience in the field of automation. With over 20 years of industry experience, Wu has made significant contributions to both academia and engineering projects.

Throughout his career, Wu Peng has participated in numerous national and international engineering projects. Some of his most notable projects include the development of an intelligent control system for oil refineries, the design of a cutting-edge distributed control system for petrochemical plants, and the optimization of control algorithms for natural gas pipelines.

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Upstream and Downstream Straight Pipe Requirements for Flow Meters

Updated April 2026 — By Sino-Inst Engineering Team

Straight pipe length is one of the most overlooked variables in flow meter accuracy. The 10D upstream, 5D downstream rule appears in nearly every standard and installation guide, but applying it correctly requires understanding why the numbers exist and where exceptions apply.

Upstream and Downstream: The Basics

Upstream is the pipe run before your flow meter. Downstream is the run after it. The upstream section determines whether the flow profile entering the meter is stable and fully developed. The downstream section provides space for the meter to make its measurement without interference from what comes next.

A fully developed flow profile means the velocity distribution across the pipe cross-section has reached equilibrium. In straight pipe with constant diameter, this typically takes 40-50 pipe diameters to achieve after a major disturbance like an elbow or tee.

The 10D/5D Rule Explained

This rule comes from empirical testing and flowmeter standards. D is the internal pipe diameter. So for a 2-inch nominal pipe (actual ID ~1.938 inches), 10D upstream = ~19.4 inches, and 5D downstream = ~9.7 inches.

The 10D upstream requirement exists because most flow meters reach acceptable accuracy at that point, even if the flow profile hasn’t fully developed. Orifice plates and differential pressure meters benefit most from this length. Magnetic and Coriolis meters tolerate shorter distances.

The 5D downstream requirement varies. Some meters need 3D, others need 5D or more. This accounts for meter response time and the pressure recovery zone immediately after the measurement point.

Flow Meter Type Comparison

Requirements by Meter Type

Orifice Plate Meters

Orifice plates are sensitive to inlet velocity profile. Beta ratio (ratio of orifice diameter to pipe diameter) directly affects requirements. At beta = 0.5, you may need 15D upstream. At beta = 0.7, 10D often suffices. The beta ratio changes the pressure drop and flow coefficient, which means the flow disturbance upstream has more or less impact on accuracy.

Field installations with two elbows in the same plane (90° apart) upstream of an orifice meter will show 2–4% higher discharge coefficient than the same meter with 15D straight pipe. This is why standards require either adequate straight run or flow conditioning devices.

Magnetic Flow Meters

Magnetic meters measure the voltage induced by fluid crossing perpendicular electrodes. This measurement is largely immune to velocity profile shape. You can often install one with 5D upstream and 3D downstream, even after an elbow, without significant accuracy loss.

The exception is extreme swirl. If the flow is rotating as it enters the meter, the voltage pattern shifts. This occurs when elbows are stacked perpendicular to each other (one horizontal, one vertical). Even then, 5D straight pipe usually corrects it.

Clogging concerns are the primary reason to maintain minimum straight pipe on magnetic meters—not to stabilize the velocity profile, but to allow solids to remain suspended in the center of the pipe rather than settling near electrodes.

Vortex Flow Meters

Vortex meters measure frequency of fluid oscillations downstream of a bluff body. Swirl entering the meter causes the shedding frequency to shift unpredictably, reducing accuracy. This makes vortex meters more demanding than orifice plates in terms of upstream requirements.

A common mistake is assuming vortex and orifice requirements are the same. Field data shows vortex meters need 15–20D upstream to tolerate two perpendicular elbows. With one elbow and 10D straight pipe, accuracy suffers noticeably in some flow conditions.

Ultrasonic Flow Meters (Transit-Time)

These meters calculate flow by measuring signal propagation time in two diagonal paths through the pipe. Velocity asymmetry—faster flow on one side—causes measurement error. Fully developed, symmetric flow is essential for accuracy above ±2% uncertainty.

Installation guidelines typically specify 10–15D upstream and 5D downstream. After a single elbow, the flow remains asymmetric well past 10D, so if you’re installing after an elbow, consider 20D of straight pipe or a flow straightener.

Turbine Flow Meters

Turbine meters are mechanically simple but sensitive to yaw (flow angle) and swirl. The rotor responds differently depending on the axial component versus the tangential component of velocity. This sensitivity demands good inlet conditions.

Most turbine installations need 10D upstream minimum. Some manufacturers specify 15D after elbows. Downstream, 5D is typical, though backpressure constraints (such as high-pressure applications) sometimes allow as little as 2D.

Coriolis and Positive Displacement Meters

These meters require no straight pipe for accuracy because they measure mass flow or volumetric displacement directly, independent of velocity profile. You can mount them immediately after an elbow with zero impact on measurement accuracy.

Coriolis meters do require some downstream space—not for the meter itself, but for pressure recovery. After the U-tube vibration channels, the flow expands back into the pipe. Allowing 2–5D downstream improves system stability and reduces noise in the signal.

Flow Conditioners and Alternatives

When you can’t meet straight pipe requirements, flow conditioners reduce the needed upstream length from 10D to as little as 2–3D. Common types include tube bundle straighteners, perforated plates, and honeycomb elements.

A tube bundle straightener (arrays of small tubes parallel to flow) costs €300–800 and works reliably. It recovers ~1D of pressure downstream, meaning your permanent pressure drop stays low. This is the best option in tight spaces.

Perforated plate straighteners are cheaper (€100–300) but cause higher permanent pressure loss. They’re adequate for low-speed applications or when small-scale mixing won’t hurt your measurement.

Never use a conditioner as a substitute for good upstream design if you can build the pipe properly. Straighteners add cost, maintenance, and pressure drop. Build 10D upstream when the space exists.

Common Installation Mistakes

Mistake 1: Assuming 10D is sufficient after any disturbance. It isn’t. A single elbow needs 10D, but two elbows (especially perpendicular elbows) need 15–20D for vortex or ultrasonic meters.

Mistake 2: Installing the meter too close to a tee junction. Tee junctions create complex flow patterns that persist for 20–30D. Always measure straight pipe distance from the meter, not from the tee itself.

Mistake 3: Neglecting downstream requirements. A 5D downstream run is just as important as upstream. Many sites focus only on upstream, then install a valve 2D downstream, invalidating both the upstream investment and the meter’s accuracy.

Mistake 4: Applying differential pressure meter rules to ultrasonic or turbine meters. Ultrasonic and turbine meters are more demanding. Don’t assume DP meter guidelines work for other types.

Mistake 5: Installing a flow conditioner, then positioning the meter immediately after it. Conditioners smooth the profile over a distance, not instantly. Leave 2D between the conditioner outlet and the meter.

Frequently Asked Questions

Featured Flow Meters from Sino-Inst

Magnetic Flow Meter

DN10-DN600 | Accuracy: ±0.5% | 4-20mA/HART | Conductive liquids

View Details

Vortex Flow Meter

DN15-DN300 | Gas/Steam/Liquid | Accuracy: ±1.0% | Temp: -40~350°C

View Details

Ultrasonic Flow Meter

DN15-DN6000 | Non-invasive | Accuracy: ±1.0% | Clamp-on/Insertion

View Details

KimGuo11

Wu Peng, born in 1980, is a highly respected and accomplished male engineer with extensive experience in the field of automation. With over 20 years of industry experience, Wu has made significant contributions to both academia and engineering projects.

Throughout his career, Wu Peng has participated in numerous national and international engineering projects. Some of his most notable projects include the development of an intelligent control system for oil refineries, the design of a cutting-edge distributed control system for petrochemical plants, and the optimization of control algorithms for natural gas pipelines.

drurylandetheatre.com

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

Posted on April 18, 2026 by KimGuo11

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.

Item	SI-100 Standard	SI-100 Ex (ATEX/IECEx)
Probe type	Rigid stainless rod, 316L	Rigid stainless rod, 316L
Measuring range	0.2 m – 6 m	0.2 m – 6 m
Resolution	0.01 mm	0.01 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
Output	4-20 mA / HART / Modbus RTU / 0-10 V	4-20 mA + HART (Ex ia) / RS-485 (Ex ia)
Power supply	24 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 pressure	0 – 4 MPa (40 bar)	0 – 4 MPa (40 bar)
Process connection	1″ NPT / G1″ / DN50 PN16 / DN50 PN40 flange	Same as standard
Float (included)	SUS304 ring float, 50 mm OD, ≥ 0.6 g/cm³	SUS304 ring float with Ex cable gland
Housing	Aluminum die-cast, IP67	Aluminum die-cast, IP67
Cable entry	M20 × 1.5	M20 × 1.5 with Ex cable gland
Hazardous area	Safe area only	Ex ia IIC T6…T4 Ga (Zone 0)
Approvals	CE, RoHS	CE, 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:

Tank	Working Level Needed	Probe Ordered	Output Wired To
2.5 m vertical day tank, diesel	0 – 2.4 m	2500 mm rigid, 4-20 mA HART	Allen-Bradley AI card
0.8 m mixing vessel, IPA	0.1 – 0.7 m	800 mm rigid, Modbus RTU, Ex ia	Schneider M340 RS-485
4.2 m underground petrol tank	0 – 4.0 m	4200 mm rigid, 4-20 mA HART, Ex ia	Station 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.

Configuration	Probe Length	Unit Price (USD, Qty 1-4)	Lead Time
SI-100 Standard, 4-20 mA	≤ 1.0 m	$680	5 days (stock)
SI-100 Standard, 4-20 mA + HART	≤ 2.0 m	$880	10 days
SI-100 Standard, Modbus RTU	≤ 3.0 m	$1,150	10 days
SI-100 Ex ia, 4-20 mA + HART	≤ 6.0 m	$1,650	15 days
SI-100 with Stilling-Well Chamber	Configured	$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.

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KimGuo11

Wu Peng, born in 1980, is a highly respected and accomplished male engineer with extensive experience in the field of automation. With over 20 years of industry experience, Wu has made significant contributions to both academia and engineering projects.

Throughout his career, Wu Peng has participated in numerous national and international engineering projects. Some of his most notable projects include the development of an intelligent control system for oil refineries, the design of a cutting-edge distributed control system for petrochemical plants, and the optimization of control algorithms for natural gas pipelines.

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Verabar Flow Meter: Averaging Pitot Tube Specs & Comparison

Posted on April 18, 2026 by KimGuo11

Updated on April 18, 2026 — The Verabar flow meter is an averaging pitot tube that measures flow by sensing differential pressure across multiple ports in a pipe cross-section. It handles pipe sizes from DN50 to DN6000, covers gas, steam, and liquid service, and delivers ±1% accuracy with far less permanent pressure loss than an orifice plate. This page covers the Verabar working principle, full specifications, and a head-to-head comparison with the Annubar.

Contents

• What Is a Verabar Averaging Pitot Tube Flow Meter?
• How Does a Verabar Flow Meter Work?
• Verabar Flow Meter Specifications
• What Is the Difference Between Verabar and Annubar?
• What Pipe Sizes and Fluids Suit a Verabar?
• FAQ

What Is a Verabar Averaging Pitot Tube Flow Meter?

A Verabar flow meter is a multi-port averaging pitot tube that measures volumetric or mass flow rate by calculating the average velocity pressure across a pipe diameter. Unlike a single-point pitot tube that samples velocity at one location, the Verabar uses four or more sensing ports distributed along the probe length to capture the actual velocity profile, including boundary layer effects near the pipe wall.

The technology was originally developed by Yokogawa (formerly Dietrich Standard) under the Verabar trade name. It belongs to the family of differential pressure flow elements but differs from orifice plates, Venturi tubes, and flow nozzles in one critical way: the Verabar is an insertion element. It slides into the pipe through a single penetration point, so installation does not require cutting the pipe or breaking flanged joints on large-diameter lines.

This insertion design makes the Verabar the preferred DP element for pipes above DN200 (8 inches). An orifice plate for a DN600 line is heavy, expensive, and causes 40–70% permanent pressure loss. A Verabar in the same line causes roughly 3–5% permanent pressure loss and costs a fraction of the orifice assembly.

How Does a Verabar Flow Meter Work?

The Verabar works by measuring the difference between total pressure (impact) and static pressure at multiple points across the pipe diameter, then averaging those readings into a single DP signal.

Multi-Port Averaging Principle

The probe body has two internal chambers. The upstream face contains multiple impact ports (typically 4–8 depending on pipe size) that sense total pressure — the sum of static pressure and velocity pressure. The downstream face has low-pressure ports that sense static pressure plus a slight negative pressure from wake effects.

Each impact port is positioned at a specific distance from the pipe center according to the equal-area method (Chebyshev spacing). This ensures that each port represents an annular ring of equal cross-sectional area, so the arithmetic average of all port readings equals the true mean velocity across the full pipe section.

DP Signal and Flow Calculation

The averaged high pressure and averaged low pressure are routed to a differential pressure transmitter. The transmitter outputs a DP signal that relates to velocity by the Bernoulli equation:

V = K × √(2 × ΔP / ρ)

Where V is velocity (m/s), K is the flow coefficient (determined by probe geometry), ΔP is the measured differential pressure (Pa), and ρ is the fluid density (kg/m³). Volumetric flow rate Q then equals V × A, where A is the pipe cross-sectional area.

The Verabar’s bullet-nose profile generates a stronger DP signal than round or diamond-shaped averaging pitot tubes. Typical DP output runs 2–5 times higher than a standard round pitot probe at the same velocity, which improves the signal-to-noise ratio and extends the usable turndown range.

For applications where flow rate needs to be expressed in gallons per minute rather than standard volumetric units, see flow meters with GPM units.

Verabar Flow Meter Specifications

The table below lists the standard specification range for Verabar averaging pitot tube flow meters. Actual limits depend on the specific model variant (insertion vs flanged) and process conditions.

Parameter	Specification
Pipe Size Range	DN50–DN6000 (2″–240″)
Accuracy	±1.0% of reading (typical); ±0.5% with in-situ calibration
Repeatability	±0.1% of reading
Turndown Ratio	10:1 (standard); up to 15:1 with high-sensitivity DP transmitter
Max Operating Pressure	40 MPa (ANSI 2500 class)
Temperature Range	−40°C to +450°C (standard); up to +650°C with ceramic-coated probe
Probe Material	316L SS (standard), Hastelloy C-276, Monel, Duplex 2205
Process Connection	Insertion (compression fitting), flanged (ANSI 150–2500)
Output Signal	4–20 mA with HART (via DP transmitter); optional Modbus, FOUNDATION Fieldbus
Permanent Pressure Loss	3–5% of measured DP (vs 40–70% for orifice plate)
Straight Pipe Requirement	8D upstream / 4D downstream (minimum); 15D/7D recommended

The straight pipe requirements above are general guidelines. Actual upstream/downstream distances depend on the type of disturbance (elbow, tee, valve). For detailed spacing rules by fitting type, refer to the upstream and downstream straight pipe reference.

What Is the Difference Between Verabar and Annubar?

The Verabar (Yokogawa) and Annubar (Emerson/Rosemount) are both averaging pitot tube flow meters, but they differ in probe profile shape, signal strength, and clog resistance. The table below compares the two on the parameters that matter most for selection.

Feature	Verabar	Annubar (485)
Probe Profile	Bullet-nose (rounded leading edge)	T-shaped (flat leading edge)
DP Signal Strength	Higher — rounded profile creates stronger wake separation	Moderate — T-shape produces lower DP at same velocity
Accuracy	±1.0% of reading	±0.75% of reading (Annubar 485 with calibration)
Repeatability	±0.1%	±0.1%
Clog Resistance	Good — bullet nose sheds debris; self-cleaning in moderate-particle flows	Moderate — T-shape can collect buildup on leading face
Permanent Pressure Loss	3–5% of DP	4–8% of DP
Max Temperature	+450°C (std); +650°C (special)	+450°C (std); +600°C (special)
Max Pressure	ANSI 2500 (40 MPa)	ANSI 2500 (40 MPa)
Pipe Size Range	DN50–DN6000	DN25–DN2400
Typical Cost (DN300)	$800–$1,500	$1,200–$2,500
OEM / Manufacturer	Yokogawa (Dietrich Standard)	Emerson (Rosemount)

When to Choose Verabar Over Annubar

Choose the Verabar when you need coverage for very large pipes (above DN2400), when the process fluid carries light particulates (the bullet nose is less prone to fouling), or when the project budget is tight. The Verabar also generates a stronger DP signal at low velocities, which helps in turndown-sensitive applications like natural gas distribution lines.

Choose the Annubar when the application requires traceable ±0.75% accuracy without in-situ calibration, when you already have a Rosemount DP transmitter infrastructure, or when the pipe is below DN50 (the Annubar goes down to DN25).

Both options produce far less permanent pressure loss than orifice plates or flow nozzles. For a broader comparison of DP flow elements including Venturi tubes, see the flow element selection guide.

What Pipe Sizes and Fluids Suit a Verabar?

The Verabar averaging pitot tube covers DN50 to DN6000 (2″ to 240″), making it one of the widest pipe-size ranges among all flow meter types. Its sweet spot is DN200 and above, where competing technologies become impractical or prohibitively expensive.

Gas Applications

Natural gas, compressed air, nitrogen, flue gas, and biogas. The Verabar’s strong DP signal works well with gases because gas DP readings are inherently small. Typical gas velocities range from 3 m/s to 60 m/s. For custody transfer, pair with a multivariable DP transmitter that compensates for pressure and temperature in real time.

Steam Applications

Saturated steam and superheated steam up to +450°C (or +650°C with special probes). The insertion mounting style is a major advantage for steam service — hot-tapping the probe into a live steam line takes less than an hour, with no shutdown required. Steam velocities from 5 m/s to 80 m/s are within the standard operating range.

Liquid Applications

Water, condensate, light hydrocarbons, and chemical solutions. For dirty liquids with suspended solids, select a probe with purge ports that allow periodic cleaning without removal. The Verabar is not recommended for high-viscosity fluids (above 30 cP) because low Reynolds numbers distort the velocity profile and degrade accuracy.

Sizing Consideration for Large Pipes

For pipes above DN1000 (40″), the probe length exceeds 1 meter. At this length, structural vibration from vortex shedding can become a concern. Verify that the probe’s natural frequency is at least 3× the expected vortex shedding frequency at maximum velocity. Most manufacturers provide vibration analysis as part of the sizing calculation for DN1000+ applications.

Featured DP & Averaging Pitot Flow Meters

Sino-Inst manufactures averaging pitot tube flow meters equivalent to the Verabar design, along with companion DP transmitters and alternative flow elements for pipes below DN50.

Averaging Pitot Tube (Verabar-Style)

Verabar averaging pitot tube for DN50-DN6000 gas, steam and liquid lines. Just 3-5% permanent pressure loss vs 40-70% for orifice plates — huge energy savings on large pipes.

Smart DP Transmitter SI-3051

SMT3151DP smart DP transmitter with German MEMS monocrystalline silicon sensor. HART and RS485 Modbus RTU protocols, 0.075% accuracy — the go-to for flow, level and density loops.

Orifice Plate Flow Meter

SI-LG orifice plate flow meter — the standard DP primary element for steam, gas and clean liquids. Supports concentric, segmental and eccentric plates, pairs with any smart DP transmitter.

FAQ

What is a Verabar flow meter?

A Verabar flow meter is an averaging pitot tube that measures flow by sensing differential pressure at multiple points across a pipe diameter. It was developed by Yokogawa (originally Dietrich Standard) and uses a bullet-nose probe profile to generate a strong, stable DP signal. It covers pipe sizes from DN50 to DN6000 and works with gas, steam, and liquid.

How accurate is a Verabar flow meter?

Standard accuracy is ±1.0% of reading with factory calibration. With in-situ calibration against a reference meter, accuracy can reach ±0.5% of reading. Repeatability is ±0.1%. These figures hold across the 10:1 turndown range; accuracy degrades below 10% of full-scale flow.

Can a Verabar be installed without shutting down the line?

Yes. The insertion-type Verabar supports hot-tap installation, where a valve and fitting assembly allow the probe to be inserted into a pressurized, flowing pipe. This is one of its major advantages for retrofit applications in steam, gas, and water systems where shutdown is costly or not allowed.

What maintenance does a Verabar need?

Routine maintenance involves checking the impulse tubing for condensate (gas/steam service) or air (liquid service) and verifying the DP transmitter zero. In dirty service, periodic purging or rod-out of the sensing ports prevents buildup. The probe has no moving parts, so mechanical wear is not a factor. Typical inspection interval is 12–24 months depending on fluid cleanliness.

How does a Verabar compare to an orifice plate?

The Verabar causes 3–5% permanent pressure loss versus 40–70% for an orifice plate. It is cheaper and faster to install on large pipes (DN200+) because it does not require flanged pipe modification. However, the orifice plate has a longer track record in custody-transfer applications and is backed by more extensive standards (ISO 5167). For pipes below DN100, an orifice plate is often more practical and equally affordable.

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Get a Verabar Flow Meter Quote

Sino-Inst supplies Verabar averaging pitot tube flow meters in insertion and flanged configurations, with optional integrated DP transmitters. We provide sizing calculations, material selection support, and hot-tap installation guidance for pipes up to DN6000. Tell us your pipe size, fluid, and operating conditions — we will send you a spec sheet and delivered price within 24 hours.

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Verabar is a registered trademark of Yokogawa Electric Corporation. Annubar is a registered trademark of Emerson Electric Co. Product names are used for reference purposes only. Sino-Inst is an independent supplier and is not affiliated with Yokogawa or Emerson.

KimGuo11

Wu Peng, born in 1980, is a highly respected and accomplished male engineer with extensive experience in the field of automation. With over 20 years of industry experience, Wu has made significant contributions to both academia and engineering projects.

Throughout his career, Wu Peng has participated in numerous national and international engineering projects. Some of his most notable projects include the development of an intelligent control system for oil refineries, the design of a cutting-edge distributed control system for petrochemical plants, and the optimization of control algorithms for natural gas pipelines.

drurylandetheatre.com