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6 votes
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For a small valve in a fluid system, what is the relationship between pressure and flow rate?

I think the best (and simplest) way to describe something like this is Bernoulli's equation. $$P+\rho gh+\frac12 \rho v^2=constant$$ To use this, we're looking only at instantaneous velocity, ...
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5 votes
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What type of liquid flow control could this device use?

I'm going to cheat by referencing the patent. ;) Automatic Bar Controls owns the Wunderbar site and has a patent on the product. The patent is US008925769. The actual detail drawings don't seem to be ...
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5 votes

For a small valve in a fluid system, what is the relationship between pressure and flow rate?

Yep, the answer is a bit more interesting. The mass flow rate ($\dot m$) will vary as $C_d A \sqrt{2 \Delta P}$ (discharge coefficient, cross sectional area, and change in pressure across the valve). ...
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4 votes
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Solenoid valve pressure drop

A valve that is smaller than the pipe diameter will reduce the flow rate, but so will any valve. When calculating what sort of pressure/head loss (pressure and head are equivalent) a system will have, ...
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4 votes

What is this plumbing apparatus?

it has to be water for fire because its red. its on the out side so they can control the water without going into the building. the open pipe is to drain the water for maintenance. it does not have a ...
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  • 41
4 votes
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Divide Flow and Maintain Pressure

Short answer: I suspect that so long as your pump is a positive displacement pump (ex: the "vibratory pump" or "rotary vane pump" as described in this webpage about espresso pumps) and is sized to ...
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3 votes
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Is there a (sort of inverse security) valve which opens if one connected side has a pressure below a certain value?

You're looking for a pressure regulator (and this is indeed what you need in your use case, but that is another question.) The regulator works so that over a range of flows, the pressure on the outlet ...
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  • 4,618
3 votes

Does this exist? -Sliding Fluid Restrictor -Solenoid Valve -Ball Valve

Look at pinch valves: A small piece of tubing that can be pinched shut pneumatically or mechanically (solenoid). When open, you have the full diameter of your tubing. The only part that touches the ...
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3 votes
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Does this exist? -Sliding Fluid Restrictor -Solenoid Valve -Ball Valve

What you are describing is a gate valve and you are correct in assuming that this would not cause foam. Unfortunately, I do not think that gate valves are manufactured in the small size that you need. ...
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  • 1,167
3 votes

Decoding pump- valve analogy for medical instrument

My first guess for any medical pump is a peristaltic pump, as they can pump one fluid then another without contamination (by swapping lines). Couple this with the fact that they can also be multi-...
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  • 3,525
3 votes

Is it possible to replicate a Tesla valve in large scale?

This device works on momentum effects. If the fluid had no momentum, it could just follow the channels wherever they go, and the resistance would be the same in both directions. In the context of ...
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3 votes
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Service Life of a Flashback Arrestor

The manufacturer says this about maintanence: annual testing of the non-return valve, body leak tightness and flow capacity is recommended WITT is happy to supply special test equipment ...
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  • 4,618
3 votes
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Can PWM be used to control the flow of a solenoid valve?

It is possible to modulate the drive of some types of solenoid fluid valves to ultimately regulate the pressure of the fluid at their output port. I have designed a product that does excatly that. ...
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3 votes

Valve first,then heat exchanger OR heat exchanger first then valve

I think the key information is that the liquid is saturated. This means any reduction in pressure will lead to partial vaporization and two phase flow. For heat tranfer best overall heat transfer ...
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3 votes

Check valve with precise cracking pressure

Check Valves are available with adjustable cracking pressures, using a preload spring to control the poppet force, for example: http://www.my-ssp-usa.com/products/valves/check-valves/adjustable-cpa ...
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3 votes
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How to inflate or deflate a bouncy ball that lacks a standard valve?

Yes, normally you can pull those plugs out - takes a strong grip or « folding » the ball to be able to push on the inner end of the plug... Here is a photo with such a plug taken out:
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2 votes

Sizing a pressure safety valve for two-phase flow

While designing a relief the valve flow rate is the deciding variable. To calculate its value in two phase flow different models can be used like HEM, drift flux, separated flow, etc. For this ...
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2 votes

LO/LC, CSO/CSC Valve Definition

That would be Process Industry Practices, Practice Ref. PIC001. Issued 7/15/1998. Appendix A1 contains exactly what you listed. Edit: I just came across this online: PIC001 Sample, Not for ...
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  • 528
2 votes

How to evaluate solenoid valve specifications

You need verify that your replacement has: 1/16" orifice(commonly available) Now, what are the size of the theads on the inlet and outlet(1/8" npt?) it might be stamped somewhere on the valve body. ...
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  • 1,578
2 votes

Is there and easy way to go from 1000 psi to 45 psi without a complicated pressure regulator

As far as engineering systems go, it doesn't get much simpler that a pressure regulator; single or double. The mechanical feedback is solid solution. Wiki link for pressure regulator operation (for ...
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  • 7,469
2 votes

Automatic siphon above max height

I think you can create a self-starting siphon if you are able to add pipe to both ends of the "drain pipe." You'd extend the output end downwards until the exit of the pipe is below the bottom level ...
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2 votes

Which components to use for a CO2 gas storage?

Your option 1, done "according to specs": Two check valves and a pressure regulator with separate output and regulation input (these are usually joint; output pressure being the regulating/feedback ...
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2 votes
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Liquid vs. gas check valves

No, liquid check valves function on density, viscosity or velocity or a combination and the mass is taken into account - gas check valves are designed to deal with a fluid 700 or more times less dense ...
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2 votes

Deflection of a stack of disks under applied force/pressure

Between disc 1 & 2, there is a reaction force on disc 1 which is not going to act on the edge rather at the distance of 2nd disc edges. This means you need to have the model of 1st disc bending ...
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2 votes
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Is there a male and female valve that is closed until connected together?

There are many, many different commercially-available designs of fluid connectors that shut off automatically when disconnected and open up when connected. They are available in plastic and metal, ...
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2 votes

How to periodically shut down a recirculating hot water solar thermal system

I would not mess around like this at all. I would make a secondary heat dump (old radiator in the garden, swimming pool...) and divert excess heat there.
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2 votes

Is there a type of check valve that allows gas to flow in both direction but stops liquid from flowing back?

If the flow rate is low for the gas then a ball that floats on the liquid will work - similar to how most wet vacs stop liquid getting into the motor...
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2 votes

Does it make sense to have a pressure and flow controller on a single closed line?

In addition to NMech's answer, the pressure regulator sets the maximum pressure that the system will see while the flow control limits the maximum flow that the downstream system will receive. This ...
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  • 8,249
2 votes

Can air flow occur in both directions in a 2 way solenoid valve?

A typical 2 way solenoid valve would not restrict airflow towards one direction. So in your case is perfectly valid, since you will be removing the pressure from the inlet. What you would normally do ...
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1 vote
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Toy ball check valve functionality and details

Depends on the design - some just use a soft plastic tube that collapses in on itself to seal. That is why some inflating kits have long needle adaptors amongst others in them tapered or parallel. ...
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