One reason why the pointer of shock-resistant pressure gauge is not at 0 position

In the verification process, some shock-resistant pressure gauges can be qualified without removing the small rubber plug at the top of the case, while some shock-resistant pressure gauges can be qualified only by removing the small rubber plug. There is atmospheric pressure in the case of shock-resistant pressure gauge, so why are the products in the same batch different? Is it correct to remove the small rubber plug when using the shock-resistant pressure gauge?

Then let's make a little analysis of the above situation:

1. First of all, the user should operate according to the "instruction manual" provided by the manufacturer to avoid checking some instruments.

And some misunderstandings in use. It is stipulated in the instruction manual of the shock-resistant pressure gauge that "during instrument verification, the sealing screw of the oil filling hole on the watch case should be loosened or the rubber sealing plug on the oil flushing hole should be pulled up to prevent the gas in the watch case from holding back and affecting the verification result".

From the instruction manual of the shock-resistant pressure gauge, it is required that all shock-resistant pressure gauges should "loosen the sealing screw of the oil flushing hole on the watch case or pick up the rubber sealing plug on the oil flushing hole" during verification.

2. Generally speaking, most of the shock-resistant pressure gauges that affect the verification results due to the pressure-holding in the watch case are shock-resistant pressure gauges with small range. According to the experience of market manufacturers, most of them are instruments below 0.6Mpa, especially those with 0.6Mpa and 0.25Mpa. Because of the thin wall of the spring tube and high sensitivity, if the pressure-holding in the watch case will have a great impact on the shock-resistant pressure gauges during verification, the verification is generally unqualified. For shock-resistant pressure gauges above 1Mpa, due to the high rigidity of the spring tube, even if the rubber sealing plug on the oil flushing hole is not pulled up during verification, the residual gas in the gauge will not have much influence on the verification result page, especially when the measuring range is larger.

Precautions for anticorrosion of stainless steel pressure gauge

In the maintenance of pressure gauges, it is very important to pay attention to the anticorrosion of pressure gauges and stainless steel pressure gauges:

1. For general corrosive media, if the stainless steel spring tube can resist corrosion for 1 ~ 2 years, it can be used as a pressure gauge for ammonia. When installing, the pressure guide tube should be short, and the buffer coil should be replaced with a buffer tank to prevent impurities from clogging.

2. If the medium is corrosive to stainless steel and copper, the buffer tank can be replaced by an isolation tank, and corrosion-resistant isolation liquid can be added. The type of isolation fluid can be selected according to the properties of the medium to be tested, but it is better to use it for more than half a year without deterioration. If the common isolation liquid is not suitable, fluorine chlorine oil can be used as isolation liquid, but the price is very expensive, so the isolation tank should be made small, and the fluorine oil should be recovered and reused when disassembling.

3. Diaphragm pressure gauges can be used. At present, there are molybdenum, titanium and tantalum sheets. The pressure is transmitted between the diaphragm and the spring tube with methyl silicone oil, and the minimum range can be 0 ~ 100 kPa. If the diaphragm material is not corrosion-resistant, a layer of F46 (perfluoroethylene propylene) diaphragm can be added, but the sensitivity of the instrument is reduced. F46 can also be directly used as the isolation diaphragm, but attention should be paid to the permeability of the medium, and fluorooil can be used as the transfer liquid, which can play a double isolation role.

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