What is hydrostatic pressure transmitter?

Hydrostatic Pressure Transmitters is an instrument that measures the hydrostatic pressure or differential pressure exerted by a hydrostatic head.

Feel the measured pressure through the remote transmission device installed on the pipeline or container. The pressure is transmitted to the main body of the transmitter through the filling silicone oil (or other liquid) in the capillary tube. Then there is the delta chamber and the amplifier circuit board in the main body of the transmitter. Convert into 4-20mA DC signal output. HP Smart can communicate with a HART handheld communicator. Use it to set, monitor, or form an on-site monitoring system with the host computer.

Hydrostatic Pressure Transmitters are often used to measure the level, flow, and pressure of liquids, gases, or steam under high working pressure environments.

Features of Hydrostatic Pressure Transmitter

The Hydrostatic pressure transmitter is used to measure the liquid level, flow, and pressure of the liquid, gas or steam under high working pressure, and then convert to 4~20mA DC signal output.

The Hydrostatic pressure transmitter is used to measure the liquid level, flow, and pressure of the liquid, gas or steam under high working pressure, and then convert to 4~20mA DC signal output.

high static pressure transmitter
  • The high hydrostatic pressure transmitter can measure differential pressure below 32MPa hydrostatic pressure.
  • With 32MPa working pressure and overload protection.
  • Ensuring reliable application of the transmitter in Hydrostatic pressure systems.

Read more about: Steam pressure transmitter-Pressure measure on steam pipeline 

Specifications of Hydrostatic Pressure Transmitter

Measure Range of Hydrostatic pressure sensor:

Differential pressure: 0-1.3-6790KPa
Hydrostatic pressure: 32MPa

  • Use object: liquid, gas or steam
  • Output signal: 4-20mA dc. Output superimposed HART protocol digital signal (two-wire system)
  • Power source: external power supply 24V dc. Power supply range 12V ~ 45V
  • Installation in dangerous places:
    • Flameproof  ExdIIBT5Gb;(explosion-proof certificate no. :CE16.1163)
    • Intrinsically safe ExiaIICT4/T5/T6Ga;(explosion-proof certificate no. : CE15.2354X) ;
  • Accuracy: ± 0.1%, ±0.2%
  • Stability: ±0.25%/6 months of maximum range
ModelTransmitter type
HPAbsolute pressure transmitter
CodeScale range
20-0.10~3.5kPa(0-10~350mmH2O)
30-0.8~8.0kPa(0-80~800mmH2O)
40-4.0~40kPa(0-400~4000mmH2O)
50-20~200kPa(0-2000~20000mmH2O)
60-70~700kPa(0-0.7~7kgf/cm2)
70-210~2100kPa(0-2.1~21kgf/cm2)
80-700~7000kPa(0-7.0~70kgf/cm2)
90-2.1~21MPa(0-21~210kgf/cm2)
00-4.1~41MPa(0-41~4100kgf/cm2)
CodeOutput form
ELinear output 4-20mAdc
SFLinear/square root output 4-20mAdc +HART signal,,Full function buttons on site
FMODBUS-485 signal
CodeStructural materials
Flange connectorExhaust/Drain valveIsolation diaphragmFilling liquid
22316 Stainless steel316 Stainless steel316 Stainless steelSilicone oil
23316 Stainless steel316 Stainless steelHastelloy CSilicone oil
24316 Stainless steel316 Stainless steelMonelSilicone oil
25316 Stainless steel316 Stainless steelTantalumSilicone oil
33Hastelloy CHastelloy CHastelloy CSilicone oil
35Hastelloy CHastelloy CTantalumSilicone oil
44MonelMonelMonelSilicone oil
CodeShell materialConduit inlet dimensions
ALow copper aluminum alloy polyurethane coatingM20×1.5
BLow copper aluminum alloy polyurethane coating1/2-14 NPT
CStainless steelM20×1.5
DStainless steel1/2-14 NPT
CodePressure connection
L11/4NPT-18 Internal thread(excluding waist joint standard)
L21/2NPT-14 Internal thread
L3M20×1.5 External thread
CodeOptional parts
M4LCD multi-power digital display head
B1Pipe bending bracket
B2Plate bending bracket
B3Pipe mounting bracket
C02M20×1.5 nut and Φ 14 pressure short tube
C121/2NPT-14 external thread and Φ14 pressure short tube
C221/4NPT-18 external thread and Φ14 pressure short tube
C321/4NPT-18 to M20×1.5 external thread
C421/2NPT-14 to M20×1.5 external thread
C431/2NPT-14 to 1/4NPT-18 internal thread
C441/2NPT-14 to 1/2NPT-14 external thread
C451/2NPT-14 to G1/2 external thread
D1The side discharge valve is on the upper part
D2The side discharge valve is on the upper part
X1Oil ban
DaFlameproof ExdIIBT5Gb;(explosion-proof certificate no. : CE16.1163)
FaIntrinsically safe ExiaIICT4/T5/T6Ga;(explosion-proof certificate no. : CE15.2354X)

Hydrostatic Pressure Transmitter Applications

  • Viscous medium at high temperature
  • Crystallizable medium
  • Precipitating medium with solid particles or suspended matter
  • Strong corrosive or highly toxic medium
  • It can eliminate the phenomenon that the pressure guiding tube leaks and pollutes the surrounding environment. It can avoid the instability of the measurement signal when the isolation fluid is used. The tedious work of frequently supplementing the isolation fluid is required.
  • Continuous and accurate measurement of interface and density
  • The remote transmission device can avoid the mixing of different instantaneous media. So that the measurement result truly reflects the actual situation of the process change.
  • Occasions requiring high hygiene and cleanliness
  • For example, in the production of food, beverage and pharmaceutical industries, it is not only required that the parts of the transmitter contacting the medium meet the hygienic standards. It should also be easy to wash. To prevent cross-contamination of different batches of media.

Hydrostatic Pressure

Hydrostatic pressure is the pressure generated by the weight of the liquid above the measurement point when the liquid is stationary. The height of the liquid column with uniform density is proportional to the hydrostatic pressure. As the weight of the fluid exerting downward force from above increases, the hydrostatic pressure increases in proportion to the depth measured from the surface.

Read more about: Differences! Static pressure vs dynamic pressure vs total pressure

If the fluid is inside the container, the depth of the object placed in the fluid can be measured.
The hydrostatic characteristics of a liquid are not constant, and the main factors affecting it are the density and local gravity of the liquid. In order to determine the hydrostatic pressure of a particular liquid, both quantities need to be known.

The deeper an object is placed in a fluid, the greater the pressure it bears. This is because the weight of the fluid is higher than its weight. Due to the weight of the fluid, the denser the fluid above it, the greater the pressure on the submerged object.

Measuring principle

The pressure in the liquid increases as the filling height increases. The hydrostatic pressure is transmitted to the measuring unit through the stainless steel diaphragm. Bubbling, accumulation of liquids, fluctuating electrical characteristics, and container design will not affect the measured value.

Formula for calculating hydrostatic pressure

The formula for calculating the hydrostatic pressure of a column of liquid is:

Phyd = h.ρ.g

Prel = h.ρ.g

Pabs = h.ρ.g + Patm

Phyd = Hydrostatic Pressure (Pa)
Prel = Relative Pressure (Pa)
Pabs = Absolute Pressure (Pa)
Patm = Atmospheric Pressure (Pa)
h = Liquid Height (m)
ρ = Liquid Density (kg/m3)
g = Local Gravity (m/s2)

The above calculation formula is also the working principle of hydrostatic liquid level sensor.

The hydrostatic pressure sensor measures the hydrostatic pressure applied by the hydrostatic head. Output 4-20mA.
Use a hydrostatic pressure transmitter to measure the storage tank and pump inlet. And other applications where hydrostatic pressure is used to determine the liquid level.

Hydrostatic Pressure Sensor/Transmitter can also be used with paperless recorder.

Hydrostatic Level Sensor measures the hydrostatic pressure by the submersible pressure sensor. The static pressure of the liquid is proportional to the height of the liquid. Then the static pressure was converted into an electrical signal. Convert to analog signal output or 4-20mADC. With digital display. For water level measurement, hydrostatic level sensor is a low cost type. Different types of measuring cells are used in level measurement based on the hydrostatic principle.

Lightning protection, anti-corrosion, explosion-proof optional. IP68 is optional.

Read more about: Hydrostatic Level Sensor

The basic working principle of Hydrostatic Level Sensor is static pressure level measurement.

In liquid, the pressure generated at a certain depth is generated by the weight of the medium itself above the measurement point. It is proportional to the density of the medium and the local acceleration of gravity.

The formula P = ρgh reflects the proportional relationship between them.

Where P = pressure, ρ = medium density, g = gravity acceleration, h = depth of measurement point.

Therefore, the physical quantity measured by the input liquid level gauge is actually pressure. It can be understood by the calibration unit mH2O of the input level gauge. The actual liquid level must be obtained by conversion after knowing the two parameters of density and gravity acceleration. In the industrial field, such conversion is usually performed by a secondary instrument or PLC.

The Hydrostatic Level Sensor mainly measures corrosive liquids such as hydrochloric acid, hydrogen peroxide, etc. Or chemical and electroplating wastewater. Mainly used in measuring corrosive media. It has the advantages of strong corrosion resistance and stable performance.

There are various methods and techniques for measuring fluid level using hydrostatic pressure sensors. Depending on the installation, they all have advantages and disadvantages. Hydrostatic pressure measurement is an accurate and convenient technique for determining fluid height or volume.
Let’s take a look at each according to the installation location of the hydrostatic pressure sensor.

Externally mounted type

Image source: https://www.yourlevelexperts.com/zh-hant/product/hydrostatic-pressure/

The Hydrostatic pressure liquid level sensor can be installed to the outside of the container through threads or flange fittings. If necessary, capillaries can also be used.

Submersible type

Picture source: network picture

If the externally mounted sensor is not available, a submersible pressure sensor can be used. The electrical connection with IP68 rating is suitable for long-term permanent immersion. The electronic equipment of the sensor can be protected from the external environment.

Read more about: [What is and How it Works]Hydrostatic Level Sensor

DP transmitters are Differential Pressure Transmitters. DP transmitter measures the pressure difference between the gas or liquid at both ends of the transmitter. Output 4~20mA, 0~5V. Used for liquid level, density, and pressure of liquid, gas, and steam.

DP transmitters are different from pressure transmitters as they have 2 pressure interfaces. With flanges, capillaries, valves, brackets, throttle devices. Differential pressure transmitters are used to measure the level, density, and flow of liquids, gases, and vapors. Then convert it into 4–20mADC current signal output.

Read more.

pressure transducer often called a pressure transmitter, is a transducer that converts pressure into an analog electrical signal.

Although there are various types of pressure transducers, one of the most common is the strain-gage base transducer.

The conversion of pressure into an electrical signal is achieved by the physical deformation of strain gauges, which are bonded into the diaphragm of the pressure transducer, and wired into a Wheatstone bridge configuration.

Pressure applied to the pressure transducer produces a deflection of the diaphragm, which introduces strain to the gages.

The strain will produce an electrical resistance change proportional to the pressure.

Read more.

Hydrostatic pressure transmitter fault debugging steps:

How to debug the fault of Hydrostatic pressure transmitter

Total Time: 30 minutes

Check the power supply

Check if the power supply of the differential pressure transmitter is reversed, and whether the positive, and negative poles of the power supply are connected correctly.

Measure the power supply

Measure the power supply of the transmitter, whether there is 24V DC voltage. It must ensure that the power supply voltage to the transmitter is ≥12V
(that is, the voltage of the transmitter power input terminal is ≥12V).
If there is no power supply, check whether the circuit is disconnected, whether the instrument is selected incorrectly (input impedance should be ≤250Ω), and so on.

Check the display meter

If the pressure transmitter is equipped with a meter head, it is necessary to check whether the dislay meter is damaged. You can short-circuit the two wires of the meter head first. If it is normal after a short circuited, it means the head is damaged.
If the meter head is damaged, Then you need to change the header.

Check the current

If there is a problem with the differential pressure transmitter, connect the ammeter to the 24V power supply circuit to check if the current is normal.
If it is normal, the transmitter is normal. In this case, check if other instruments in the loop are normal.

Connect the power supply

Connect the power supply to the transmitter power input terminal, and connect the power cable to the power supply wiring port.
If you still have any question with the selection, application, and use of pressure transmitters, you can just contact our engineer today.

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Hydrostatic pressure transmitter/sensor measures the level, density, and pressure of liquid, gas, or steam. And then converts it into a 4-20 mA DC signal output. The Hydrostatic pressure transmitter can communicate with the HART communicator intelligently. Use it to set, monitor or form a site monitoring system with the host computer. Use a Hydrostatic pressure sensor to measure tanks, processing vessels, headers, pump inlets and others using hydrostatic pressure to determine the liquid height. SI3051HP Hydrostatic pressure transmitters, with working Hydrostatic pressure up to 32Mpa.

Sino-Inst offers a variety of Hydrostatic Pressure Transmitters for industrial pressure measurement. If you have any questions, please contact our sales engineers.

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