Structure principle and verification method of diaphragm pressure gauge

Diaphragm pressure gauge is suitable for measuring the pressure or negative pressure of various fluid media with certain corrosiveness, non-solidification or non-crystallization. The pressure guide system and shell of stainless steel corrosion-resistant diaphragm pressure gauge are all stainless steel, which has strong corrosion resistance. It is mainly used to measure the tiny pressure of gas and liquid in chemical, petroleum and textile industries, especially in corrosive and viscous media (non-solidified and non-crystallized). The stainless steel shock-resistant diaphragm pressure gauge is filled with damping liquid and supporting buffer device, which has good shock-resistant performance. The vibration-resistant diaphragm pressure gauge can be used to measure stably when the pressure of the measured medium has a strong pulse change or pressure shock and is often suddenly unloaded in the production process, as well as in places with large environmental vibration. The corrosion-resistant and shock-resistant diaphragm pressure gauge has the characteristics of both corrosion-resistant and shock-resistant diaphragm pressure gauges.

Diaphragm pressure gauge is mainly composed of lower connector, upper connector, elastic diaphragm, connecting rod, movement, pointer, dial and so on.

Under the action of pressure, the measured working medium directly acts on the elastic diaphragm, and the diaphragm elastically deforms upward (measuring positive pressure) or downward (measuring negative pressure), and the gear shaft of the movement is driven to rotate by the connecting rod mechanism fixed in the center of the diaphragm, so that the pointer indicates the measured pressure value on the dial.

calibration method

1. Verification method of indication error: The indication verification of pressure gauge shall be carried out according to the graduation line marked with numbers, and the pressure shall be gradually and steadily increased (or decreased) during verification. When the indication reaches the detection upper limit, the pressure source shall be cut off, and the pressure shall be kept for 3MIN, and then the pressure shall be steadily decreased (or increased) in reverse order according to the original verification point.

2. Return error, which is the absolute value of the allowable error in accordance with the regulations during the step-up (or step-down) and step-down (or step-up) verification for the same spot check.

3. Tap the displacement. For each point of verification, during the step-up (or step-down) and step-down (or step-up) verification, the indicated value change caused by the lightweight case is not more than 1/2 of the absolute value of the specified allowable error.

4. Indication error. For each verification point, when boosting (or depressurizing) and depressurizing (or boosting) verification, the difference between the front and rear indications of the lightweight case and the indication of the standard should meet the requirements.

Classification of industrial automation instruments

Release date: August 1, 2022 Author: Click: 17

Pressure gauge manufacturers show you the classification of industrial automation instruments.

Pressure gauge manufacturers classify industrial automation instruments into the following types according to their functions:

I. detection instrument

Detection instrument refers to the general name of instruments that can feel the measured variable, such as electromagnetic flowmeter, battery-powered electromagnetic flowmeter and plug-in electromagnetic flowmeter. It can be a transmitter, a sensor or an instrument with both detection elements and display devices. Among them, the transmitter is a detection instrument that senses the measured variable by means of detection elements and converts it into a standard signal. The so-called standard Huai signal is the signal that the upper and lower limits of the change range have been standardized.

(for example: 4-2 OMA DC, 20-100 kPa, etc.).

According to different measured objects, different modifiers can be added to the names of measuring instruments or transmitters, such as flow measuring instruments, electromagnetic water meters, open channel flowmeters, high-voltage electromagnetic flowmeters, temperature transmitters, etc.

2. Display instrument

The display instrument is used to indicate and record the value of the measured variable, or the sewage flowmeter is used for the abnormal state of the production process, so that the operator can know and supervise the production situation at any time.

There are many kinds of display instruments, which can be divided into three types according to their display modes: analog, digital and graphic display.

3. Adjust the instrument

Regulating instrument, also known as control instrument, is an instrument that automatically controls the controlled according to the control law. The regulating instrument used to realize closed-loop control is usually called regulator. According to the different control functions, regulators can be divided into differential regulators, proportional-integral regulators and proportional-integral differential regulators.

4. Actuator

Actuator, also known as terminal control element, is used to directly change the conveying quantity of materials in the forward path of the control system according to the control signal sent by the regulator, so as to achieve the purpose of adjusting process parameters such as temperature, pressure, flow rate and liquid level.

Actuator usually includes two parts: actuator and adjusting mechanism.

The regulating valve commonly used in process control is an actuator that adjusts the diameter of the fluid passage by the control signal to change the sinker I.

5. Calculation instrument

Calculation instrument is an instrument that can perform mathematical operations on multiple input variables. According to the operational relationship between the beat and the input variable t, the calculation instruments can be called adder, multiplier, square root and so on.

6. Set point generator

Set point generator is also called given unit, current meter and submersible electromagnetic flowmeter. In the control system, it can send a signal to the regulator (regulator) as a function of time or other variables to set the expected value of the controlled variable. If the set value (given value) changes regularly with time, time program control can be realized.

7. Signal converter

An instrument that can convert a signal into another signal (usually a standard signal) is called a signal converter, or simply a converter. For example, a converter that converts a standard current signal into a standard air pressure signal is called an electro-pneumatic converter, and vice versa.

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