Effect of pressure on flowmeter accuracy
The effect of pressure on the accuracy of the flowmeter is obtained by testing the same flowmeter at different pressures using a static weighing water flow standard device with adjustable working pressure. At very low temperatures, the mechanical properties such as yield point, tensile strength, elongation, throttling, and impact test values of metal materials are very different from those at normal temperature: At very low temperatures, although the tensile strength of metal materials has increased, However, the ductility is reduced, and the impact test value also decreases significantly with the material. Therefore, instrument materials with sufficient resistance to destruction must be used at extremely low temperatures so that they do not cause brittle failure. This material is called a low temperature material. ％的镍钢， 35 ％的镍钢。 The most common materials used today are: stainless steel, aluminum alloy, 90 % nickel steel, 35 % nickel steel.
If the platinum resistance wire is heated to a temperature value higher than the temperature of the fluid, then when the fluid flows through the platinum resistance wire, it will take away the heat in it, change its temperature, that is, change its resistance value. If a vortex is generated above the cylinder, then the fluid enters from the upper pressure guide hole, flows out from the lower pressure guide hole, and passes through the platinum resistance wire again, which will change its resistance value again. Therefore, it can be concluded that the change of the resistance value corresponds to the change of the flow, which corresponds to the frequency of the vortex. Therefore, by detecting the resistance change frequency of the platinum resistance wire, the eddy frequency can be obtained, and then the flow meter can be obtained.