Pressure

A pressure transmitter is an industrial measuring instrument that converts a pressure signal into a standardized electrical output signal. Its core principle is that the sensing element, based on technologies such as piezoresistive, capacitive, or piezoelectric sensing, detects the pressure of a gas or liquid and generates a small electrical signal, which is then processed by built-in amplification and conditioning circuits to output standard signals such as 4-20mA, 0-10V, or HART/RS485 for acquisition and control by PLCs, DCSs, or display instruments. From a technical perspective, it integrates pressure sensing, signal conversion, and remote transmission functions into one unit, featuring high accuracy, a high turndown ratio, and good temperature compensation capability. It can achieve continuous and stable pressure monitoring under demanding conditions such as high temperature, high pressure, corrosion, and vibration, making it an indispensable basic measurement unit in industrial automation systems.

• Widely used in general industry and process industry
• Multiple certifications such as CE, ATEX, CSA, IECEx, CCS, 3-A, and NEPSI
• Suitable for various industrial media, including liquids, gases, and steam, as well as liquid-level measurement applications.
• LED display, digital output, easy integration and compatibility
• Accurate pressure measurement for reliable and safe process control
• Independently developed and controlled core sensing technology, supporting extensive sensor customization

Aluminum alloy

Lightweight, high strength, and excellent heat dissipation performance. After surface coating treatment, it has good corrosion resistance and can provide stable and reliable protection for internal circuits in demanding industrial environments.

316L stainless steel

It has excellent corrosion resistance and impact resistance, and can operate stably for a long time in highly corrosive, high-humidity, and high-salt environments such as chemicals, petrochemicals, and marine applications, providing a high level of protection for internal circuits.

Oil and gas

Pressure monitoring of wellhead gathering and transportation pipelines, Inlet and outlet pressure monitoring of heating furnaces, oil-gas separation and crude oil dehydration monitoring, natural gas purification and pressure regulation monitoring, etc.

Downstream Oil & Gas Applications

Crude oil booster station monitoring, oil depot tank farm monitoring, gas station vapor recovery monitoring, cooling tower circulation system monitoring, slop oil pump station monitoring, etc.

New energy

Pressure/liquid level monitoring for hydrogen production systems, separator liquid level monitoring, pressure monitoring and control for lithium battery kilns, etc.

Marine and shipbuilding

Cooling water circulation system monitoring, power center instrument monitoring, water circulation cooling system monitoring, temperature control system monitoring, etc.

Power

Combustion furnace instrument monitoring, steam drum and turbine monitoring, steam generator monitoring, flue gas treatment tower monitoring

Chemicals

Distillation column instrument monitoring, metering tank and storage tank liquid level monitoring, reactor/separator instrument monitoring, reactor kettle instrument monitoring, etc.

Clarify the measurement type and range parameters

• Distinguish the measurement type: gauge pressure, absolute pressure, differential pressure; for liquid level, use a differential pressure transmitter, and calculate the differential pressure value corresponding to the liquid level.
• Range selection: It is recommended that the normal working value fall within the 30% to 70% range of the span to ensure accuracy; reserve overload margin to withstand water hammer and impact pressure. Do not select the model based only on the process full scale.
• For differential pressure liquid level measurement, the static pressure (maximum working pressure of the vessel) must be confirmed. The pressure rating of the transmitter body must be greater than the design pressure of the equipment. Exceeding the static pressure will damage the sensor.
• Differential pressure liquid level: Calculate the positive migration/negative migration amount in advance, and confirm during selection that the instrument supports the migration function; when the density of the medium in the tank fluctuates greatly, differential pressure is not suitable for liquid level measurement.
• Determine the accuracy class and turndown ratio (adjustable ratio) to meet process control requirements. Do not blindly pursue high accuracy and cause cost waste.

Process Medium and Wetted-Part Materials

Temperature conditions (medium temperature + ambient temperature)

Output signal and system matching 

• Conventional industry: 4-20mA two-wire; if local configuration and remote diagnostics are required, choose 4-20mA + HART protocol.
• Digital DCS/PLC: Choose Profibus PA, FF bus, or Modbus RS485 as needed.
• Confirm cable distance and whether shielded cable is required. Evaluate signal attenuation for long-distance signal transmission.

Explosion protection, ingress protection rating, and on-site environment

• Flammable and explosive hazardous areas: Strictly confirm the explosion protection rating (intrinsic safety Ex ia / flameproof Ex d). The explosion protection certification must match the on-site area classification. Ordinary non-explosion-proof models cannot be used in explosion-proof areas.
• Enclosure ingress protection rating: For indoor and outdoor use, at least IP65 is recommended for dust protection and water spray protection; for open-air and humid, water-vapor-heavy conditions, increase the ingress protection rating.
• For sites with high vibration levels, confirm the transmitter's vibration resistance specifications and avoid installing it at locations subject to severe vibration.

Process connection and accessory selection

Differential Pressure Liquid-Level Measurement (Key Considerations)

• For liquid level measurement in closed vessels, the negative migration caused by gas phase condensate must be considered.
• If the medium is prone to crystallization and sedimentation, give priority to insertion flanges to reduce diaphragm scaling.
• Interface measurement (two liquids layered): Ensure that the liquid level is always higher than the upper pressure tapping point; changes in medium density will directly cause liquid level measurement errors.

Shanghai LEEG Instruments Co., Ltd. is one of the most professional pressure manufacturers and suppliers in China, featured by good service and competitive price. Please rest assured to buy high quality pressure made in China here from our factory. Contact us for more details.