I want to pump LOX into a pressure vessel at 2 bar (say). So for pumping it what should be safest flow rate?

  • $\begingroup$ The question as-is probably cannot be answered: What kind of propellants are we talking about? "Safe" in which respect? With what kind of tank/tank-design? $\endgroup$
    – DarkDust
    Jul 23, 2018 at 10:08
  • $\begingroup$ This is way too broad (there are too many kinds of rockets and liquid propellants) as well as unclear what you mean by safe. Try to be more specific about a given type of rocket and liquid propellant. But that may not be enough, as "safest" is probably too subjective. See if you can identify a question where a fact-based answer will suffice. $\endgroup$
    – uhoh
    Jul 23, 2018 at 10:39
  • $\begingroup$ @Amar if you are going to edit your question like that, in the very least read my answer to your previous phrasing and account for it in your question. You have addressed 1 aspect but completely ignored the other 2. $\endgroup$
    – anon
    Jul 23, 2018 at 14:32
  • $\begingroup$ I put a reopen but if you are going to get more you need to research and refine your question. $\endgroup$
    – Muze
    Jul 23, 2018 at 16:59

1 Answer 1


I probably shouldn't answer this question, then again I can't vote to close because it is to broad and ambiguous, so I will try and give an suitable answer to help the OP out.

First aspect: What is the propellant?

Different propellants can be piped at different rates mostly related to their chemical volatility. If your propellant was water for instance, you could push that as fast as it isn't sawing your tank in half.

Second aspect: What are diameters of your hose and ports?

If you have a wide enough port you can fill your tank in 5 secs.

Third aspect: What is the overall engineering of your system?

This sort of relates back to the first two aspects but is meant more encapsulate all the other factors that could result in explosions. Say you are piping liquid O2. You could pipe it as fast as you wanted provided you kept it cold, the pipe from exploding, and eliminated any chances for it reacting with something like hydro-carbons. Usually though, extremes of this aren't pursued as they become economically infeasible and simply not worth the effort.

  • 2
    $\begingroup$ I'm sorry that trying to help the dude understand the complexity of the question he is asking upsets you. Technically though he did not explicitly ask for a numerical answer, he asked for the safest flow rate which I described is one that is based on the engineering of his system. :D $\endgroup$
    – anon
    Jul 23, 2018 at 12:05
  • $\begingroup$ @anon I think uhoh's point was, you could've posted a comment like: "Before answering this I will need information such as: 'What is the propellant? What are diameters of your hose and ports? What is the overall engineering of your system?' this is too vague to answer as is." Instead of posting an answer to the question, making it so that the OP cannot delete it and repost it later if he wanted to. $\endgroup$ Jul 23, 2018 at 13:27
  • $\begingroup$ @MagicOctopusUrn I get that, but there isnt enough space in a comment to describe all that. Obviously, there is a lot the OP doesnt know, moreover I strongly doubt he will ever be able to describe a system in enough detail to get a meaningful answer so I figure the least I can do is outline some of the variables he can consider to research to solve whatever problem he is contemplating. $\endgroup$
    – anon
    Jul 23, 2018 at 13:34
  • $\begingroup$ Hopefully the question will be modified to something like "what factors affect fastest safe fill time, and what things can be done differently to make it faster, because I am building a strategic nuclear weapon and I need to know how to launch it quickly..." $\endgroup$
    – uhoh
    Jul 23, 2018 at 13:45

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