Liquid column pressure gauge The working principle of liquid column pressure gauge is to use the pressure generated by the height difference of the liquid column on both sides of the U-shaped glass tube to balance the pressure of the measured medium. The greater the difference in liquid column height, the greater the pressure of the measured medium, and the pressure value can be read directly from the scale. Liquid column pressure gauge has the advantages of simple structure, convenient use, cheap price, etc., but it can not measure higher pressure, can not be automatically indicated and recorded, so the scope of use is limited. Usually used to measure the pressure value in the boiler furnace and flue, the shockproof pressure gauge is composed of a pressure guide system (including joints, spring tubes, current limiting screws, etc.), a gear transmission mechanism, a number device (pointer and dial) and a shell (including a case, cover, glass, etc.).

Shock-proof pressure gauge, shock-proof pressure gauge housing is air-tight structure, can effectively protect the internal parts from environmental impact and pollution intrusion. A gauge filled with damping liquid (usually silicone oil or glycerin) in the housing, which can resist the vibration of the working environment and reduce the influence of media pressure pulsation. Shockproof pressure gauge [Suitable for places of severe vibration in the environment, can withstand the pulsation, impact and sudden unloading of the medium, the instrument indication is stable and clear. Widely used in machinery, petroleum, chemical industry, metallurgy, mining, electric power and other departments, to measure the pressure of copper and copper alloy non-corrosive media.

Digital pressure gauge, digital pressure gauge is an online measuring instrument. It uses battery long-term power supply mode, no external power supply, easy to install and use. The product has been widely used in petroleum, chemical industry, electric power and other fields through a pressure gauge that displays the measured pressure in digital form. Digital pressure gauge has high precision, high stability, error ≤1%, internal power supply, micro power consumption, [2] stainless steel housing, digital pressure gauge protection is strong

First, the working principle of the pressure gauge through the elastic deformation of the sensitive element in the table (bourdon tube, diaphragm, bellows), and then the pressure deformation is conducted by the conversion mechanism of the movement in the table to the pointer, causing the pointer to rotate to show the pressure. Spring tube (bourdon tube) is divided into type tube, coil spring tube, spiral tube and other types, generally using cold hardening type material blank tube, in the annealed state has a high plasticity, after pressure processing cold hardening and qualitative treatment to obtain high elasticity and strength. Under the pressure of the inner cavity, the elastic characteristics of the spring tube can be used to easily transform the pressure into the elastic displacement of the free end of the spring tube.

The measuring range of the spring tube is generally a circular diaphragm with waves in the diaphragm sensitive element, the diaphragm itself is located between two flanges, or welded to the flange or its edge is sandwiched between two flanges. One side of the diaphragm is subjected to the pressure of the measured medium, so that the small bending deformation generated by the diaphragm can be used to indirectly measure the pressure of the medium, and the size of the pressure is shown by the pointer. Compared with Bourdon tube, the diaphragm has a larger transmission force, and its vibration resistance is better because of the fixed edges around the diaphragm itself. The diaphragm pressure gauge can achieve high overpressure protection (such as the diaphragm attached to the upper flange), the diaphragm can also be added to the protective coating to improve the corrosion resistance, the use of open flange, flushing, opening and other measures can be used to measure the diaphragm pressure gauge viscosity is very large, unclean and crystalline media, the pressure measurement range of the diaphragm pressure gauge is 1600Pa ~ 2.5MPa.

The diaphragm sensitive element is composed of two pieces of diaphragm with a circular wave section that are connected together. The pressure of the measuring medium acts on the inside of the diaphragm cavity. The resulting deformation can be used to measure the pressure of the medium indirectly. The diaphragm pressure gauge is generally used to measure the micro pressure of the gas, and has a certain degree of overpressure protection. Several diaphragm sensors stacked together will produce a large transfer force to measure extremely small pressure, diaphragm pressure gauge pressure measurement range of 250Pa ~ 6000Pa

Second, the pressure gauges commonly used in industrial boilers and chemical industry are liquid column pressure gauges, spring pressure gauges, bellows pressure gauges, shock-proof pressure gauges, digital pressure gauges and so on.

Bellows gauge, bellows gauge measures the micro-pressure and micro-negative pressure of blast, inductor, flue gas and powder systems. The main structure of the diaphragm pressure gauge is composed of two parts: the diaphragm box and the transmission amplifier. The diaphragm is made of an alloy made of round box-like pressure element, when the pressure changes, it will expand or contract displacement, through the transmission and amplification lever system, so that the pointer on the trough dial to indicate the value of the measured micro pressure or micro negative pressure. Bellows pressure gauges can also be electrically charged contacts for control and protection functions.

Spring tube pressure gauge, spring tube pressure gauge structure. In the circular shell, there is a spring bend tube with an oval section (the long axis of the ellipse is parallel to the central axis of the watch hand) (commonly made of seamless copper tube or seamless steel pipe), one end of which is connected with the storage water pipe drawn from the boiler steam space to become a fixed end, and the other end is a closed free end, connected with the connecting rod. The other end of the connecting rod is a sector gear, which is connected to the pinion on the center shaft. The pointer of the pressure gauge is fixed on the central axis.

When the special spring tube is subjected to the pressure of the medium, it will make its free end move outward, and then through the connecting rod to drive the sector gear and the pinion to rotate, so that the pointer turns an Angle in the clockwise direction. The greater the pressure of the medium, the greater the rotation Angle of the pointer. At this time, the scale value indicated by the pointer on the dial of the pressure gauge is the value of the steam pressure in the boiler. When the pressure is lowered, the spring bend will contract inward, returning the pointer to the corresponding position. When the pressure disappears, the spring bend returns to its original shape, and with the help of the action of the spring, the pointer returns to the starting point (zero position). The spring tube pressure gauge has the advantages of compact structure, high degree, wide measuring range, convenient use, etc. It is used to measure the medium pressure value in the drum, header and pipeline.