Pressure is one of the important parameters in industrial production. Correctly measuring and controlling pressure is an important link to ensure the good operation of the production process and achieve high quality, high yield, low consumption and safe production. Therefore, the detection of stress has attracted more and more attention.
The electric contact pressure gauge is a kind of pressure gauge most often contacted by grass-roots verification personnel because of its wide variety, model and wide use. The general accuracy level is 1.0-4.0, especially in the measurement and control of boilers, pressure vessels or pressure pipelines. Usually, the pressure gauge is used together with the corresponding electrical devices such as relay and contactor to realize the purpose of automatic control and signal alarm for the measured and controlled pressure system. During daily use, the pressure gauge will have various problems and faults due to vibration, oil stain, wear, corrosion and other reasons, which need to be repaired and calibrated in time.
The electric contact pressure gauge is composed of a spring tube pressure gauge equipped with an electric contact. In addition to field indication, it is also used to send out a signal meaning the pressure is out of limit. Its pressure measuring principle is based on that the spring tube in the measuring system forces the end of the spring tube to have corresponding elastic deformation (displacement) under the pressure of the measured medium, and the measured value is indicated on the dial by the pointer on the fixed gear; At the same time, drive the contact to produce corresponding action (closing or opening) to make the circuit in the voltage control system connected or disconnected, so as to realize the purpose of automatic control alarm and field indication.
The electric contact pressure gauge is actually a circuit switch operated by the pressure gauge. It is only an ordinary spring tube pressure gauge with an electric contact signal device installed . The verification of the pressure part is the same as that of the ordinary pressure gauge. The difference from other pressure gauges is the reaction after it is connected. During verification, first look at the accuracy of its pressure, and then look at the sensitivity of its connection reaction. Therefore, the verification is divided into two steps:
1) For the pressure part, the indication shall be verified according to the general pressure gauge;
2) For the electrical part, after the indication verification is qualified, the electrical contact signal device shall be verified under pressure, and its connection performance shall be checked with a multimeter.
The comparison method is a common method to calibrate the pressure gauge. Install the standard pressure gauge and the tested pressure gauge on the same horizontal plane of the piston type pressure gauge or pressure calibrator. After the piston is filled with working fluid (transformer oil) and the internal air is drained, close the needle valve on the oil cup to form a closed system; Rotate the hand wheel on the piston type pressure gauge or calibrator piston to change the pressure of the extruded working fluid. The hydraulic transmission of the working fluid makes the pressure of the standard pressure gauge and the tested pressure gauge at the same level change synchronously and equal; Compare the standard pressure gauge with the indicated value of the tested pressure gauge.