Selection methods and precautions of precision pressure gauges

How to choose:
The choice of pressure gauge should be based on the specific situation and meet the technical requirements of the process. At the same time, cost issues should also be considered. When we recommend the selection of instruments, we should consider the following aspects:
(1) The physical and chemical properties of the tested medium, such as temperature, viscosity, dirtiness, corrosiveness, whether it is flammable, explosive, and easy to crystallize.
(2) Requirements for pressure measurement in the production process, such as the measured pressure range, degree, and whether remote transmission, recording, or upper and lower limit alarms are required.
(3) Site environmental conditions, such as high temperature, corrosion, humidity, vibration, electromagnetic field, etc.
In addition, for the elastic pressure gauge, in order to ensure that the elastic element works reliably within the safe range of elastic deformation, to prevent pressure damage to the elastic element and affect the life of the instrument, there must be enough room for the range selection of the pressure gauge. Generally, when the measured pressure is relatively stable, the large working pressure should not exceed 3/4 of the full scale of the instrument. When the measured pressure fluctuates greatly, the large working pressure should not exceed 2/3 of the full scale of the instrument. In order to ensure the measurement accuracy, the measured pressure should be no less than 1/3 of the full scale.
Precautions:
1. The pressure gauge must be placed vertically during the prevention and control: when installing, use a wrench to tighten it. Do not directly screw the outer case by hand, because it will damage the case. Do not let it collide during transportation to avoid damage.
2. When using a pressure gauge, pay attention to controlling its amplitude below one millimeter.
3. During use, if the pointer of the instrument cannot return to zero because the temperature in the environment is too high, you can cut the rubber plug on the case to allow the atmosphere to enter the interior of the instrument to easily solve this problem. Too.
4. When using the meter, pay attention to the outside temperature, and control the outside temperature to -25 to 55 degrees. Only in this temperature range can the pressure gauge work properly and be protected from damage.
5. The pressure gauge should be inspected regularly. The inspection cycle is at least every three months. If any fault is found during the inspection, it should be repaired in time.
6. There is also a certain range for the use of pressure gauges. This range should be controlled within the range of one third to two thirds of the maximum value of the pressure gauge.
In order to ensure the accuracy of pressure measurement, the following points must be noted when using a pressure gauge:
(1) Selection of measuring point
The selected measuring point should represent the measured pressure. The measuring point should be selected in the straight pipe section, far away from the local resistance. The impulse pipe does not extend into the measured object but should be flush with the process pipe. The inner diameter of the pressure guiding tube is generally 6~10mm, and the length should not be greater than 50mm, otherwise it will cause transmission lag. In order to prevent the pressure guiding pipe from being blocked, the pressure taking point is generally selected on the horizontal pipe. When measuring the liquid pressure, the pressure point should be in the lower part of the pipeline so that no liquid accumulates in the pressure guiding tube; if the liquid on the north side is easy to condense or freeze, a pipeline insulation device must be installed.
Install
When measuring steam pressure, a condensing pipe or condenser should be installed to condense the steam measured in the pressure guiding pipe. When the measured fluid is corrosive or easy to crystallize, the isolation fluid and isolator should be used to avoid damaging the measuring elements of the pressure measuring instrument. The isolation liquid should be selected in the liquid with high boiling point, low freezing point and stable physical and chemical properties. The pressure gauge should be installed as far as possible away from heat transfer and vibration to avoid its influence. A shut-off valve should be installed near the pressure tapping port for use in repairing the pressure gauge.
Maintenance
During use, it should be cleaned regularly to keep the pressure guiding tube and pressure gauge clean.

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