Analysis on how to verify the verification regulation of pressure transmitter

Before the use of the pressure transmitter, in order to ensure the better application of the pressure transmitter, it is necessary to verify the pressure transmitter, so what is the verification regulation of the pressure transmitter?

exterior

The nameplate of the transmitter shall be complete and clear, and the main technical indicators such as product name, model, specification and measuring range shall be indicated. The high and low pressure chambers shall be clearly marked, and the name or trademark of the manufacturer, factory number and manufacturing year shall also be indicated.

The feeder parts shall be intact, the fasteners shall not be loose or damaged, and the movable parts shall be flexible and reliable.

The coating on the surface of the shell and parts of the newly manufactured transmitter should be smooth and intact, free from rust and mildew, and there should be no debris such as chips and residues inside. There should be no defects affecting the use and metering performance of the transmitter during use and after repair.

airtightness

When the measuring part of the transmitter bears the upper measuring pressure (differential pressure transmitter is rated working pressure), there shall be no leakage or damage.

Output open circuit effect

After the open circuit test of the force balance transmitter, the normal wiring is resumed, and the change of the output range of the transmitter shall not exceed the basic regulations, and it still meets the requirements of basic error and return error.

Output AC component

For the transmitter with an output of 0-10mA, the effective value of AC voltage at both ends of the 200Ω sampling resistor should not be greater than 20mV. For the transmitter with an output of 4-20mA, the effective value of AC voltage at both ends of the 250Ω sampling resistor should not be greater than 50mV (the force balance type should not be greater than 150mV).

insulance

When the ambient temperature is 15-35℃ and the relative humidity is 45%-75%, the insulation resistance between the terminals of the transmitter shall be not less than the following values:

Output terminal grounding terminal (cabinet): 20MΩ

Power supply terminal and grounding terminal (cabinet): 50MΩ

Power supply terminal output terminal: 50MΩ

These are the main verification procedures for pressure transmitters. Everyone should pay attention to all aspects of details in the verification process.

What is the working principle of pressure transmitter? How to wire the pressure transmitter?

Principle description:

Usage: The pressure transmitter is mainly used to measure the pressure, negative pressure and absolute pressure of gas, liquid and steam, and then convert them into 4-20 mA DC signals for output.

Pressure transmitters include GP type (gauge pressure) and AP type (absolute pressure). GP and Ap can be combined with intelligent amplification board to form an intelligent pressure transmitter, which can communicate with each other through hand-held devices conforming to HART protocol for setting and monitoring. The δ chamber of GP type pressure transmitter can be used to measure gauge pressure or negative pressure because one side receives the measured pressure signal and the other side is connected with atmospheric pressure. The δ chamber of AP type absolute pressure transmitter receives the measured absolute pressure signal and the other side is sealed as a high vacuum reference chamber, which can measure exhaust system, distillation tower, evaporator and so on.

Principle: There are several commonly used principles, such as capacitance, resonant beam and silicon diffusion!

Capacitive pressure transmitter mainly consists of chamber sensitive components to realize pressure \ capacitance conversion and 4-20mA electronic circuit board to convert capacitance into two-wire system! When the process pressure is applied to the isolation diaphragm from two sides (or one side) of the measuring chamber, it is transmitted to the central diaphragm of the chamber through silicone oil filling liquid. The central diaphragm is a diaphragm with tight edges, and under the action of pressure, it produces corresponding displacement, which forms a differential capacitance change! And through the adjustment, vibration and amplification of electronic circuit board! Convert to 4-20mA signal output! The output current is proportional to the process pressure!

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