The issue with the pressure gauge’s warning line
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Guys: Does the warning line on a pressure gauge only indicate the upper limit? ? Does the upper limit refer to the upper limit specified by the process requirements, or to the rated pressure of the equipment and facilities? ? What we are asking now is that warning tapes be posted at both the start and end of the process area. I’m not sure if it’s correct; please advise.
In my opinion, it can be the upper and lower limits specified by the manufacturing requirements, or it can be the upper and lower limits for safety warnings – it depends on one’s specific requirements.
Not necessarily; it depends on your process requirements – in some cases, it is necessary to have upper and lower limits set
Can I not put it? Do I have to stick it? Is it a mandatory requirement?
Sure, we can do it according to whatever requirements the process dictates. Anyway, usually it’s they who check these local pressure gauges. As for which upper limit to use, it also needs to be discussed with the manufacturing process team; if the upper limit they require is lower than the rated pressure of the equipment, then their specified upper limit should be adopted. If it is high, then discuss with them changing it to the rated pressure of the equipment.
It must be marked; both the Technical Supervision Bureau and the Work Safety Supervision Bureau require this. Generally, it is sufficient to just draw a line, but in some manufacturing processes there are requirements specifying that a minimum value must be indicated
Check the process parameters. Generally, it’s sufficient to indicate only the upper limit.
We also mark it, but during regular inspections, they only check whether it is present or not; only a few people will verify whether the charter ticket matches the upper and lower limits you have set. We usually monitor the pressure during normal operation, and then determine a range based on those normal values in order to meet the inspection requirements. Otherwise, it’s difficult to determine the appropriate limits, and changes in production load may cause the values to exceed those limits, leading to problems during inspections. Anyway, it’s mainly sufficient to ensure that the outlet flow or pressure remains stable.
All the pressure gauges in our factory come with warning lines. Generally, markings are made by combining design parameters with the ranges specified by the relevant staff; only those who are directly involved know best about the actual working conditions.
Principles for setting the red line on pressure gauges (for reference): 1. For pressure vessels, the maximum allowable operating pressure is indicated by the red line; it must not exceed the set pressure value of the safety valve. 2. The outlet pressure of the centrifugal pump is indicated by the red line on the pressure gauge when the valve is closed. 3. The outlet pressure of positive displacement pumps is governed by the set pressure value of the pump’s outlet safety valve, which serves as the critical limit. 4. The pressure gauge on the process pipeline should have the maximum operating pressure set as the red line value. The maximum pressure for the water, steam, and air boundary conditions of the utility systems is indicated by the red line. 5. The pressure gauge at the bottom of each device should indicate the maximum operating pressure plus the static pressure of the highest liquid level.