The problems that occur in the pressure gauge verification work are solved in this way

Recently, the editor has always received private messages from many users asking: how to solve this problem in the verification work of the pressure gauge? What kind of problem and how to solve it? There are always too many questions. In order to solve your confusion, the editor has compiled the following information for you, hoping to help you. Come and see if there is something you are curious about?

 1. The difference between the oil meter and the oil-free meter

    In the industrial production process, a variety of pressure gauges need to be used, which can generally be divided into oil-free pressure gauges and oil-free pressure gauges. It is clearly stated in the verification regulations that "Oxygen pressure gauges must also be marked with the words "no oil" in red on the dial or marked with a standard oil-forbidden sign. That is, oil-free pressure gauges generally refer to oxygen pressure gauges, which cannot be used in use. Contact with oil stains, but in actual work, it is found that there are some occasions where it is necessary to use an oil-free pressure gauge. Generally, there will be two words "oil-free" on the dial or a slash on an oil pot; the oil pressure gauge can't help but be Ordinary pressure gauges can be exposed to oil pollution. In the specific verification/calibration work, it is found that some users do not choose appropriate pressure gauges according to the prompt information on the dial, such as ordinary pressure gauges in oil-prohibited occasions, or oil-inhibited occasions. Oil-prohibited pressure gauges should be selected for occasions. At the same time, there are also some measuring instruments who will send oil-prohibited pressure gauges and oil-free pressure gauges together for inspection, especially some shock-resistant pressure gauges with poor rubber plug seals, which will pollute The joint of the oil-free pressure gauge, this kind of pressure gauge must use carbon tetrachloride to completely clean the oil pollution on the surface before the verification. In the specific work, it is recommended to do publicity work for the inspection personnel, and at the same time in the verification of the pressure gauge During the process, we must pay attention to whether the head of the oil-free pressure gauge has been contaminated, especially in the receiving process, it has been found that the rubber plug of the shock-resistant pressure gauge is not tightly sealed, and there is leakage.

    2. The pointer of the pressure gauge is not at zero

    Before the pressure indication value is verified, the phenomenon that the pointer is not at the zero position often occurs. It can be divided into several situations:

(1) The pointer is close to the zero position, but not at the zero position. If the shock-resistant pressure gauge is in this case, it may be because the pressure gauge has been used in a high temperature environment for a long time or has been in a high temperature environment for a long time, causing the pressure in the inner cavity of the instrument to be greater than the external pressure. The pointer can return to zero; if it is an ordinary pressure gauge, it is recommended to repair the internal structure.

(2) The pointer is in the range from close to zero to the maximum range. This situation is generally because the pressure gauge is bumped or hit by external force during use or transportation, or the type of pressure gauge selected in actual use is improper. (For example, an ordinary pressure gauge is used in a position where the pressure value fluctuates particularly violently, and the pointer is in a small swing for a long time), most of which occur between the large dial pressure gauges.

(3) The pointer has exceeded the maximum range of the dial, and even reached the lower side of the stop pin. This situation is generally due to the improper range of the pressure gauge selected. The pressure value here exceeds the range of the selected pressure gauge. It is recommended to replace a larger range pressure gauge. When selecting the range of the pressure gauge, it is recommended to reserve a certain pressure range, and the measured pressure value should generally be controlled between 1/3 and 2/3 of the upper limit of the gauge.

3. The pressure gauge is not tightly sealed during the verification process

In the process of pressure gauge verification, it is generally necessary to install the tested pressure gauge on the tested gauge joint of the pressure gauge calibrator. After the installation of the inspected meter is completed, it is easy to have a loose seal during the pressurization process (if the working medium for verification is gas, gas leakage will occur; if the working medium for verification is liquid, there will be liquid leakage), which will lead to The pressure indication value cannot be stabilized, and the pressure drops significantly. This situation is generally due to the damage to the thread of the pressure gauge under inspection, the wrong specification and model of the standard joint selected, or the unwound raw material tape. When calibrating elastic element type general pressure gauges, pressure vacuum gauges and vacuum gauges -0.1 to 60MPa, first check the thread of the pressure gauge connector to be tested. If the thread has obvious burrs and damage, it should not be directly connected to the pressure gauge. On the standard joint of the gauge calibrator; secondly, the type of thread of the pressure gauge to be tested should be judged. The common ones are metric ordinary thread (M) and pipe thread (R). If the M thread is used, the bottom gasket is used to seal it. Whether the gasket still exists and whether the gasket is intact; if the R thread is used for thread sealing, a wrench and other tools should be used to tightly connect the pressure gauge connector and the standard nut. If there is still leakage, it is recommended to wrap the raw material tape. , Tighten the connection of the joint and the standard nut. There are also some phenomena that cannot be sealed in specific work. It is recommended to consult an experienced engineer or deal with it as unqualified.

4. The pointer is stuck or skipped during the pressure gauge verification process

During the verification process of the pressure gauge, the needle may be stuck or skipped. In this case, the common reason is that the pointer of the pressure gauge is inclined or bent, causing the pointer to contact the disk surface, and the frictional resistance is too large, which hinders the deflection of the pointer; It is also possible that the pressure gauge is squeezed or impacted during use, causing the disk surface to bend, which affects the normal deflection of the pointer. If conditions permit, it is recommended to open the dial when the pointer shaft of the pressure gauge is tilted, re-correct the pointer shaft or replace the pointer shaft; if it is not capable of maintenance, it is recommended to scrap it.

Have you learned more details about the pressure gauge now? It’s true that the work of verification is always busy and there is a panic, but we can solve all problems stably. As long as we find the root of the problem, we can completely Solve it. If a similar situation occurs in future work or in learning, you are welcome to use the editor's method to see if it is useful. For more details, please log on to www.kunkeandao.com, and there is a 24-hour customer service online to solve all your doubts.