Questions tagged [valves]

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Confusing terminology for "normally closed/open" - It means the opposite in electronics (relays) versus fluids (valves)

I'm an electrician and "normally open" / "normally closed" is well known to me. I recently started to also work on heating systems including the pneumatic system that controls some ...
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2 answers
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ELI5: How does this water (solenoid) valve work?

I took apart this hose faucet timer: When unpowered the valve is closed. When powered (either manually or by timer) it opens allowing water to flow through. I am attempting to learn how the open/...
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Mechanism of erosion in control valve flashing

My background is analytical and theoretical chemistry, but now I work as a data scientist in the oil and gas industry, working with operations data. The phenomena of cavitation and flashing erosion ...
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1 answer
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What are the issues with this ICE design?

Elaborating along this previous question, could you please invalidate this ICE design with solid authoritative arguments explaining all the flaws? Starting hypothesis: Whatever the purpose, one single ...
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Examples of Internal Combustion Engines with one valve inside the piston?

I'm searching for examples of production internal combustion piston engine, 4 stroke cycle, 2 valves per cylinder, with one inlet valve inside the piston, and one exhaust valve at cylinder head. Only ...
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1 answer
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User-settable pressure-relief valves for outdoor domestic water supply lines?

Is there such a thing as a pressure relief valve which can be attached to garden hose bibb threads that would relieve backpressure from a pressure washer, in order to protect old pipes and reduce the ...
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1 vote
2 answers
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Is there anything close to automatic shuttle valve?

I am building a pneumatic system that needs an automatic shuttle valve. That means if I apply air pressure on one of the inputs In1, it closes the other input In2 and creates a path between In1 and ...
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1 vote
1 answer
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Are there hydraulically actuated pneumatic valves?

I am working on a hydraulic system that is powered by an air-hydraulic piston pump, the pump uses pneumatic pressure to drive a piston which then pressurizes the hydraulic system. The system needs to ...
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Diesel fuel valve outdoors: Gate, Globe, or Ball?

Real world question: We need to replace an internally failed (cannot shut) gate valve installed as a shut-off valve on a 2" Diesel fuel line exposed to weather (roof top) and operating at less ...
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1 vote
2 answers
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How does this transmission valve "hydraulic computer" work?

I just came across this: The claim is that it is a kind of analogue computer. But I don't see any moving parts. How does it work? EDIT: If someone could draw lines on the diagram to illustrate, that ...
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1 answer
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Is there a pressure check valve that doesn't bleed the excess pressure?

My issue is that downstream, I have a boiler making pressure at 10.54 bar and upstream I have a system that must NOT be heated at any point beyond 130 °C. My plan is to make sure the system pressure ...
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Question about cooling load, superheat, sensing bulb and the method that decrease the pressure in the thermostatic expansion valves

I must say I am the new guy in the engineering, so there are some proper noun or common sense I don't understand, hoping someone can teach me, I have two questions below: I have searched for ...
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1 answer
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Solenoid valve that does not restrict air flow when open [closed]

I wonder if such a valve exist - a cheap solenoid valve that when open does not restrict air flow? I've only found solenoid valves for compressed air, although the opening may very (4-12mm) there is a ...
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3 answers
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Releasing compressed air with the loudest pop

Due to the dry summer I've been thinking about theory of making cracker/banger without fire. Would connecting a nozzle (de Laval?) to quick release valve from small cylinder with the pressurised air ...
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1 answer
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Plug valve problem

A pig is a solid plug that is introduced into the pipeline to be serviced. Fluid is pumped upstream of the pig to provide the necessary force to set the device in motion, and to perform the desired ...
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1 answer
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How would a gas flow switch react to falling pressure in the gas supply?

There's currently an ongoing discussion (not decision!) in Germany if households could be cut off from gas supply come winter, to make more natural gas available for industry. Of course media is full ...
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1 vote
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Understanding flow curves of an hydraulic directional proportional valve

In the picture below you can see the command signal to flow curves for a proportional valve I'm using. Since I'm using it to control the speed of a cylinder I was looking at the looped flow path ...
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2 answers
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How to connect a 1/4 NPT pressure gauge to a schrader valve while being airtight

I need to attach this pressure gauge - https://www.amazon.co.uk/gp/product/B07CXM3ZGT/ref=ask_ql_qh_dp_hza - to a schrader valve with a pipe to measure the pressure. The valve has a 1/4 NPT thread. I ...
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2 answers
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Can you make a simple hand-operated pump using two check valves?

question is basically the title. I was wondering if it would be possible to connect a check valve on each end of a squeezable bladder in order to make a simple pump. The purpose would be to make a ...
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What is the lowest energy solution for emptying a drip irrigation water collector : a mono-stable solenoid valve or a bistable coupled to a pump?

I have a water collector I want to empty everyday for drip irrigation. It is controlled by a micro-controller. I have identified three solutions: Use a bi-stable electro-valve and a pump: advantage ...
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2 answers
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Relief valve for "semi-closed" loop system (non-engineer warning :-)

My excuses in advance for the probably-bad wording of the question, I'm just an hobbyist without much knowledge in engineering. To the point I can't google for information on my problem since I don't ...
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1 answer
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Can flow rate of a small gas flow be controlled by a valve that is opened and closed rapidly in a certain frequency?

Can flow rate of a small gas flow be controlled by a small solenoid valve that is opened and closed rapidly in a certain frequency?
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1 answer
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Head loss coefficient for a valve with respect to both the open position and flow rate

This question talks about the head loss coefficient for a valve, i.e., $K_{L}$ for $h_{L} = K_{L} V^{2} / 2g$ where $h_{L}$ is head loss. First, head loss coefficient for a valve with respect to the ...
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3 votes
2 answers
161 views

Why do pneumatic valves need both a Safety Relay and an Air Dump to be safe?

If air dumps safely release pneumatic pressure from an industrial machine when an E-Stop is pressed, why is it also standard practice to cut electrical control power from the valves with a safety ...
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1 answer
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Is there any way to quantify the rate at which pressure is relieved in a reactor?

If a pressure relief valve is open, is it somehow possible to quantify the rate at which the pressure in the reactor will decrease?
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45 views

Which of these systems should reach a better vacuum?

I'm trying to find a cheap manual vacuum pump for a sample transportation container that carries oxidizable samples of thin-film magnetic materials. They already have a 15 nm Tantalum layer on top, so ...
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1 answer
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Is there a valve that will only open when input pressure is above 3 atm including when the downstream pressure is also 3 atm?

I want to use an external gear pump to pump air into a combustor at a design pressure of 3 atm. Unless i use a valve that opens at threshold pressure there is no compression - the air exists the pump ...
1 vote
0 answers
31 views

Valve solution for mixing external air into a closed loop climate controlled air circulation system

I'm looking for an electronically controlled air valve solution which would provide a way to mix external air into a closed loop air circulation system used for climate control in an enclosure. The ...
1 vote
0 answers
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What's the name of the valve that opens once pipes are mated?

I am building a wastewater system for my van (ie low pressure) and would like removable tanks for ease of emptying. I can shut off the inlet but would like to be able to drop them and automatically ...
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Controlling flow through an output pipe

I wish to limit my flow through the output to a certain exact value. In this case to 10 lpm, what method or valve can I use to this task? At the moment the flow keeps on fluctuating between 10.1-11.2 (...
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2 answers
78 views

How to simulate open and close and control valve using a simple controller

I have successfully developed a mathematical model for my physical system. My objective is to control the mass of gas in and out of the system. The mass flowrate is given by: $V_f = C_d.\sqrt{2.\frac{\...
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1 vote
1 answer
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What kind of solenoid valve should I use for vacuum?

I'm currently working on a project in which I have to control 2 solenoid valves with arduino to switch the suction of a vacuum pump from one tube to another one (tried to explain it on the photo), I'...
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1 answer
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Valves and plumbing size

I'm building a liquid rocket engine and we're using kerosene and oxygen as our propellent. Now my question is what pipe size should we use? My flow rate for kerosene is 0.160 Liters per second and we ...
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Selecting a water pump for low flow and 1 Bar pressure

I am designing a small automatic drip irrigation system. There will be about 10-15 drippers. Flow through the system will be about 1 l/minute, but this may change if expanding or reducing the system. ...
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0 answers
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Approximating volume flow based on valve opening

I want to approximate the volume flow going through heating/cooling units, but all I have are valve openings (unit=%). Since the valve does not have a linear relationship between its opening and its ...
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Pneumatically operated three way valves

I basically need to replace these valves with a modern equivalent It’s a pneumatically actuated three way valve for high pressure and flow rate (200 bar, 50 liters/minute). The liquid is basically ...
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1 vote
1 answer
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Can air flow occur in both directions in a 2 way solenoid valve?

I'm designing a system where I need to fill and exhaust air from an an air bag. The air will be supplied from a dc motor. As of right now I've been considering placing a 2 way solenoid valve for air ...
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4 votes
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Part to pierce the valve on a 16g CO2 cartridge and connect to a Solenoid valve

The specific part that I’m after is something that can connect to a solenoid valve and a CO2 cartridge that will break the seal on the end of the CO2 cartridge. The solenoid valve connection is ...
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Is there a valve design or system that can do this?

I am trying to come up with a way to bleed air from a tube to avoid air (gas) from reaching the other end of the tube. Is there a way to do this automatically? It must be able to work in all ...
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1 answer
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0 energy one way valves [closed]

Is there such thing as a check valve that takes no energy from water for water to pass through? What is the name of this/these check valve type/s? I barely know anything about engineering, just have ...
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2 votes
2 answers
23 views

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

I have seen P&IDs in which a single line has both a pressure and flow control valve. Based on my understanding of Bernoulli's equation however this doesn't make sense to me - because ultimately ...
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3 answers
91 views

How can I keep my soda bottle at atmospheric pressure while dispensing the liquid via a sealed system pump?

I am making a "bar bot" and I am trying to figure out a way to dispense soda without it going flat. I am using a bunch of peristaltic pumps: Which luckily remain sealed at rest. I was ...
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4 votes
2 answers
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Divide Flow and Maintain Pressure

Im in the process of building an espresso machine from readily available parts. I have a solenoid pump that supplies pressurized hot water to the coffee grounds. I want to be able to tune the pressure ...
1 vote
0 answers
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maintenance of steady flow through pressure or mass flow

let's say I have two points in a line, A and B. Between them there is a valve that can regulate the amount of the stream from A to B. Considering that there is a steady flow of the stream between A ...
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1 vote
3 answers
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Is there a type of check valve that allows gas to flow in both direction but stops liquid from flowing back?

I have a pressure regulator to maintain a specified pressure in a vessel that also contains a liquid. The regulator can pressurize or relieve pressure of the vessel. I want to prevent the liquid from ...
3 votes
1 answer
48 views

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

I am posed with a scenario where a hot water solar thermal system has been setup. The system comprises of a cold water tank, heating arrays and then a hot water tank. The system is closed loop and ...
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Using one electrical pump for multiple hoses

I'm currently trying to figure out a cheap way to build a cocktail machine. For now the machine should have about 20-30 possible input liquids. These liquids should remain in their original bottle ...
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1 vote
1 answer
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How to inflate or deflate a bouncy ball that lacks a standard valve?

I found this bouncy ball in my garage. It is too deflated to use and too inflated to store, so I would like to inflate it or deflate it. It doesn't have a standard valve for a bike pump: the only ...
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0 answers
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Equation to calculate flow rate

Assume you have a solid walled sphere with an opening of diameter x. The sphere has volume 0.02 litres and has air at 1.4 bars. What general equation would be appropriate to correctly size the ...
2 votes
1 answer
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Help with simple hydraulic circuit to use for a four legged Robot

Firstly i am new to hydraulics, i want to build a hydraulic circuit that powers 4 cylinders at each leg of a Quad-Wheeled-Robot. The idea is to move the Chassis of the Robot up and down in all ...