enter image description hereMy target is to create a valve with multiple inlet capillaries. And my output is a pipe of a larger diameter. I do not want to use any electrical systems, and at the same time, I want to maintain enough negative pressure inside the valve to influence the flow of fluid to be from capillaries to the pipe and not the other way round. The pipe-capillary system is evacuated and the fluid inside is at a higher than atmospheric pressure (we can assume 4-5 atm). I also wish the flow to remain laminar and avoid turbulence.

I looked into kinds of pumps which, in principle, achieve this... But I could not find any self-controlling system which does not require external power to maintain the pressure force required. Pneumatic systems like the flow valve looked promising but I could not figure out a way to achieve the requirement I am aiming for. I was thinking of inserting a high pressured section inside the valve which would push a diaphragm with constant force. And that force can be used to maintain the negative pressure that I want. Another idea with having a vacuum instead of a high-pressure fluid to achieve the same (effectively the inverse mechanism). But from a design perspective, I could not figure out a way to avoid leakage of the high pressure over time. My idea was inspired by the action of a syringe. I tried to design a CAD model for the same to simulate it... But could not figure out how to implement all that I read on this topic.

Does a valve or pneumatic system exist that achieves this (am I missing some information that I should know)? And if not, how can I make such a valve? I need to manufacture this as well, so simplicity/availability of resources is important. But any theoretically sound solution will also be greatly appreciated :)

Thanks in advance

  • $\begingroup$ So what have you calculated so far? What have you looked for and found? Do you think this is a free design service? $\endgroup$
    – Solar Mike
    Jun 18, 2018 at 10:07
  • $\begingroup$ I have updated the question with some of the research I did before posting the question. I am not an active member of this community but that does not mean that I disrespect it by taking it for granted. Did not intend to come off as a freeloader, I just didn't know how much to share. Will be mindful of this in the future. $\endgroup$ Jun 18, 2018 at 11:09
  • $\begingroup$ I'm not sure i undersand your requirement. Can you draw a sketch with where you want to have which pressure? $\endgroup$
    – mart
    Jun 18, 2018 at 13:04
  • $\begingroup$ Sorry for the unintended large image, I couldn't get it to upload at a smaller size. From the image, what I want to achieve is to create a suction of fluid from the capillaries. Since capillaries will have a tendency to pull the fluid due to surface tension, I want to nullify that and moreover force the fluid to flow to the outlet pipe. The pressure inside the capillaries and the pipe need to be the same. So I need to achieve the forced flow without altering the fluid pressure. $\endgroup$ Jun 18, 2018 at 13:24
  • $\begingroup$ Does the valve close & open, and you want to maintain negative pressure when it's closed? Or do you simply mean xou want negative pressure in the large pipe? $\endgroup$
    – mart
    Jun 18, 2018 at 14:24

1 Answer 1


Sounds like you're looking for some sort of regulator, not a valve. You did not give any indication to the size or scale of this device, so a link to a specific PN would likely not be useful.

In general, regulators are pressure-reducing devices; most of which operate passively, without electromechanical components. I think that this video, which describes the basic principle of a reg, will help you. Single Stage Regulator: Working Principle


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.