Please discuss: What should be the setting of the manual valve in front of the pressure gauge during normal production? ”Is there a problem with this question?
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This post was last edited by wt2008 on 2015-8-4 21:14. Please discuss: \"What should be the setting of the manual valve in front of the pressure gauge during normal operation?\" ”Is there a problem with this question? To be honest, this question has caused quite a lot of controversy; it’s just that it’s hidden, so people can’t see it. So I’m starting a dedicated thread today for everyone to discuss it. August 3, Daily Question (Single-choice question): During normal operation, the manual valve in front of the pressure gauge must ( ). A、Fully open B、Fully closed C、1/2 open D、1/3 open Answer: A、Fully open. I didn’t create this question myself; my skills are limited, so I can’t come up with such good questions. It was selected from the catalytic cracking-related question bank. When I was choosing, I thought this question was great and controversial. Because in actual work, we generally don’t open the pressure gauge hand valves fully; some are opened to 1/2 and some to 1/3, with no unified standard. For this question, I thought about it at the time. I thought about whether choosing A, which means fully open, was the correct answer. This is how I think about it: the question states that under normal production conditions, leakage issues should not be taken into account; therefore, we need to build systems that prevent leakage. Ignoring the issue of leakage, we only consider the measurement aspect. For accurate measurement, the manual valve in front of the pressure gauge must be fully open; therefore, option A – fully open – is acceptable. If A is not chosen, C and D can both be selected; however, from the perspective of answering techniques, this is not acceptable, as it is a single-choice question. Now let’s discuss again, in practical work, why the manual valve in front of the pressure gauge is sometimes opened to only 1/2, and in some cases to 1/3 – what is the basis for this? If a leak does occur, what good is that? What are the disadvantages of having it fully open? What’s the harm in using only 1/2 or 1/3? What to do if the valve is broken? Also, are there any design or safety specifications for this issue? Please start the discussion. There is no right or wrong; there is a reward for everything. Thank you!
If the hand valve is turned to 1/2 or 1/3 out of fear of leaks, it is a disregard for the designers. From a design perspective, the pressure tapping pipes used in field meters are designed taking into account parameters such as temperature and pressure; the material selection and pressure resistance are fully adequate. Turning the hand valve halfway open can easily lead to blockages
I answered your question by choosing the option for the smallest value, 1/3. This is related to an incident in 2013 when a company experienced deaths due to people being poisoned by acidic water; as a result, we closed all the valves located in front of the pressure gauges for hazardous materials.
This post was last edited by wt2008 on 2015-8-4 21:28. Boss, you came to reply so quickly. Here, please allow your words to be considered merely as personal opinions. Only in this way can everyone express their personal opinions. Thank you. Next, please feel free to share your different opinions. Thank you.
This post was last edited by wt2008 on 2015-8-4 21:32. Yes, I also said that in real work, many things aren’t turned on fully. Some of ours have also been like this, not fully open. It's understandable. But can we say it was completely wrong? I just wonder if there are any design or safety standards that address this aspect?
Actively participate in the discussion: This is how I answered it: During normal operation, the manual valve in front of the pressure gauge must ( ). D. When operating the 1/3 heavy oil line, it is sufficient to slightly open the pressure gauge hand valve to prevent leaks from causing accidents. Comments on wt2008: It’s fine from a security perspective, and many places also do it this way. Since this question takes measurement aspects into account alone, the answer is A. Published the day before yesterday at 17:27 IP:175.162.246.184:44681
When operating it, turn it fully open and then back half a turn to prevent the valve from sticking due to long-term disuse.
In actual production, when the pressure is stable, it needs to be fully opened; generally, 2/3 of the opening is sufficient； For pressure pulses, such as at the outlet of a reciprocating pump, setting it to 1/3 is usually sufficient; setting it too high makes it harder to read the pressure display.
According to normal operating procedures, it should be fully opened; based on operational experience, it should be opened to 1/3. This is because there have been multiple instances of leaks and fires at pressure gauge connections due to vibrations and other factors. So now, most companies require it not to be turned on fully.
The answer is 1/3 opening. Personally, I think of shock-proof pressure gauges for pumps, especially those used with heavy oil at high temperatures; if such a pressure gauge fails, it can indeed lead to leaks and fires. With many shock-proof pressure gauges, there have been cases where the shock-absorbing fluid leaked out and entered the gauge itself.
I’ve learned something new – the manual valve in front of our pressure gauge was always left fully open, and the company never issued any instructions regarding this. It turns out there are so many potential risks in the production process; it seems I really lack experience :D