To keep pressure gauges sensitive and accurate，in addition to reasonable selection and correct installation, the maintenance and inspection of pressure gauges should be strengthened during the operation of boilers and pressure vessels.
1. The pressure gauge should be kept clean, the glass on the dial should be bright and clear, so that the pressure value indicated by the pointer in the dial can be easily visible. And the pressure gauge with broken glass on the dial or blurred dial scale should be abolished.
2. The connecting pipe of the pressure gauge should be blown regularly to avoid blockage, especially the connecting pipe used for gas with more oily dirt or other viscous substance.
3. You should often check whether the rotation and fluctuation of the pressure gauge pointer are normal, and whether the cock on the connecting pipe is in the fully open position.
4. The pressure gauge must be calibrated regularly, and the frequency can be based on the specific conditions:
1) After the pressure gauge has been in operation for three months, level 1 maintenance must be applied mainly to check whether the pressure gauge can return to zero position, and whether the tee cock and the water trap joint are leaking. And we must check and flush the water trap to ensure smooth flow.
2) After a year of operation, level 2 of maintenance must be applied. At this time, the pressure gauge can be disassembled and sent to the measurement department for verification and lead sealing. When we disassemble and check the trap, the threaded fasteners should be found intact. Disassemble and check the three-way cock, grind the sealing surface to ensure that it is tight without leakage, and the connection thread should be intact. Store the trap, remove the rust and paint the three-way cock.
5. When the pressure gauge is inaccurate during operation, it must be replaced in time. The replacing gauge must be a lead-sealed pressure gauge that has been verified by the metrology department and is within the validity period of the verification or a new one with a factory certificate. Before changing the meter, the three-way cock must be screwed to the position of flushing the pressure gauge, and the dirt in the trap pipe must be flushed.
The above is about the maintenance method of the pressure gauge. After the pressure gauge calibrator is used for one stage, clean the internal oil circuit regularly and replace with fresh medium to prevent the unclean material of the person being inspected from clogging the pipeline and corroding the body. Only the correct use and attention to the maintenance of the instrument can prolong the service life of the pressure gauge and the accuracy of the results.
Pressure gauges are commonly used mechanical equipment in the process of industrial control and measurement. Pressure gauges can be classified as mechanical and electronic pressure gauges. And mechanical pressure gauges are widely used because of their good elastic components and high mechanical strength, especially in industrial production.
The working principle of mechanical pressure meters is to indicate the pressure value through the elastic deformation of the internal elastic sensitive elements under pressure. Mechanical pressure meters generally use spring tubes, diaphragms, bellows as elastic elements. After these elastic elements deform, they will be amplified by a gear transmission mechanism to display the corresponding pressure value.
The pressure measured by a meter is relative, as the atmospheric pressure being a relative point. The result displayed by the pressure meter is also the pressure of the measured object under atmosphere. The pointer indicates the pressure value in the measuring range of the pressure meter, and the dial corresponding to the pointer is usually 270 degrees.
1. The role of pressure gauge:
Pressure is one of the most important process parameters in industrial production. If the pressure does not meet the requirements, it will affect production efficiency, reduce product quality, and even cause serious accidents. Therefore, pressure measurement has a special position in industrial production. The correct use of pressure gauges is quite necessary for accurately measuring the pressure value.
The danger of the pressure gauge itself is very low, especially when compared with the production system it monitors, its danger is almost negligible. The reason why the use of pressure meters needs to be highly valued is that pressure meters are the prerequisite for automatic interlocking devices, sensing devices and protection devices, and are the way for various reaction devices to obtain pressure information.
The role of pressure gauges in the production system is irreplaceable. The small problems in the operation of pressure meters may be hidden dangers, especially for pressure meters used for monitoring of hazardous substances such as flammable, explosive, corrosive, and toxic substances. Once the pressure measurement is wrong, it may directly lead to the leakage of hazardous substances, causing a huge environmental disaster. The safe use of pressure gauges is the responsibility of every company and every operator. This requires companies that use pressure gauges to fundamentally improve the safety of pressure gauges, reduce the risk of pressure gauge safety from the system, and provide a good environment for the use.
2. Three hidden dangers and their elimination methods of pressure gauges
Pressure gauges are common measuring instruments. With the development of the instrument industry, pressure gauges have been widely used in various fields such as industrial production.
The pressure gauge can intuitively display the pressure changes in each process link, gain insight into the condition formation in the product or medium process, monitor the safety trends in the production and operation process, and build a rapid and reliable safety guarantee through automatic interlocking or sensing devices . This has played an important role in preventing accidents and protecting personal and property safety, and is called the "eye" of safety.
However, in actual production and life, pressure gauges are neglected or used illegally, which brings hidden dangers to safety. It is usually shown as below:
1). Irregular installation and configuration.
The current regulations have clear requirements for the configuration, installation, use, maintenance and inspection of pressure gauges. Problems are prominent as there are many changes to specifications as one’s wish in actual assembly. In minor parts or double (multiple) meter monitoring places, the number of settings is reduced, the disk diameter and range are not suitable for work requirements, and special instruments are used under special conditions such as flammable, explosive, toxic and corrosive.
2). Not enough attention is paid to daily use and maintenance. The inspection and clean of the device are not regular during use. There is no record of usage, and there are phenomena such as non-return to zero or severe fluctuations of the pointer, peeling off of the protective film of the anti-blast hole, corrosion of the dial or broken glass and unclean dial.
3). The inspection and verification work is not implemented. The verification period of the pressure gauge is usually once half a year. Compulsory verification is a legal measure to ensure reliable technical performance of pressure gauges, accurate value transfer, and effective safety in production. Because some users do not have a good understanding of the safety function of the pressure gauge, they do not apply for verification in advance. So exceeding the verification period is very serious. Especially the newly purchased pressure gauge can be installed and used after the verification is qualified, but the first use verification rate of the new meter is still very low.
Compared with the production system, the pressure gauge is too small to cause any accidents. However, with the pressure gauge as the major device, the automatic interlocking device, the sensing device, and the protection device as the supporting sections, and the small and subtle perception of vision, the fortress of safe construction is irreplaceable. "Thousand-mile long embankment collapsed in ant dens." Contempt and neglect of details is a sacrilege of security. As one of the safety accessories, the pressure gauge not only displays a few pressure numbers, it uses clever "eyes" to monitor the slightest "leakage hole", and always guards the door to product safety, personal safety, and environmental safety. Especially when used in dangerous places such as the production, storage, and transportation of flammable, explosive, and toxic substances, stress factors play a key role in preventing catastrophic accidents. The contribution of pressure gauges to safety cannot be underestimated. First of all, users should continuously improve their safety awareness and sense of responsibility, and truly manage and make good use of the characteristics of the pressure gauge to make it play the role of "eyes"; secondly, the testing and verification agency should actively perform the verification of the pressure gauge and downgrade it in time. Retire the pressure gauges that do not meet the usage requirements, and ensure that the measurement value is accurate and the performance is reliable; also, the supervision department must strictly supervise the use of the pressure gauge, and investigate and punish illegal operations and illegal use behaviors according to the law. Let us start from the details and the foundation, shine the "eyes" of safety, and jointly build a strong and safe long embankment.