What are the precautions during the application of the gas flowmeter? Posted by : admin / Posted on : May 20， 2020

1. When the operating conditions of the appearance are changed (such as medium changes, large fluctuations in ambient temperature, etc.), the zero position of the appearance should be adjusted from the beginning. At the same time, the catheter on the outside of the leveling equipment needs to be calibrated with a spirit level in order to ensure its function. Otherwise it will increase the impact of changes in operating conditions on zero drift;
2. In order to measure the large flow rate and ensure the linearity, the shunt principle can be used to expand the range of the appearance. Such as the use of bypass tubes, venturi tubes, orifice plates and other cooperative applications, the range can be expanded to tens, hundreds, and thousands of standard liters per hour, up to tens of thousands of standard cubic meters;
3. Although the specific heat of the real gas changes with the pressure and even the fluctuation of some gases is relatively large, the measurement accuracy of the appearance can still adhere to the range;
4. In addition to considering corrosion resistance, it is better to choose materials with better thermal conductivity. Taking the measurement of nitrogen as an example, it is also tested in the range of 0-100kg / cm2 pressure and 0-7 standard liters / hour flow rate. The measurement accuracy of the nickel tube is 2 to 2.5% and that of the stainless steel is 3 to 4%. (The thermal conductivity of nickel is about three times that of stainless steel).
5. Since the gas flowmeter can perform normal operations only when the specific heat of the gas is relatively stable, the specific heat value is very unstable when the gas composition is unstable, the gas is misted, and the operating conditions are imminent due to the critical zone of gas liquefaction. It is not appropriate to use this appearance;
6. If a gas medium is changed, perform calibration from scratch. In the external clarification book, it is often introduced that not re-calibration, but the conversion of the uncalibrated gas flow based on the specific heat of the two gases is simple and convenient, but it will form a large error, especially when operating under high pressure. We found that the sensitivity of the appearance is not completely proportional to the specific heat and the meter is closed, and it is better to de novo calibration;
7. The appearance is turned on and preheated before use, and the appearance is unstable before it is fully warmed up. The better model, its preheating time is less than two hours;
8. In the process of application, when the gas flow changes suddenly, it must pass through the heat transmission, and the temperature in the tube is distributed from the beginning, so the time required for the output signal to be stabilized from the beginning. In order to reduce this hysteresis, manufacturers often add differential networks to the external electrical circuits to make the output signal react quickly. This is especially important when cooperating with other appearances for flow control.