# Questions tagged [valves]

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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 ...
20 views

### 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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### 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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### 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?
119 views

### 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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### 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 ...
46 views

### 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?
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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### 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 ...
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1 vote
30 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
43 views

### 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 (...
29 views

### Adding electric control to industrial hydraulic disk brakes

I'm trying to electronically control the service brakes on some construction equipment, in addition to maintaining the normal brake pedal functionality. The disk brakes are controlled by the valve ...
62 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
222 views

### 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'...
72 views

### 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 ...
62 views

### 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. ...
31 views

### 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
79 views

### 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 ...
• 11
168 views

### 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 ...
47 views

### 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 ...
49 views

### 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 ...
19 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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### 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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### 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
39 views

### 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
245 views

### 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 ...
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### 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 ...
162 views

### 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
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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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### 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 ...
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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 ...
1 vote
435 views

### PC Controllable DC Power supply (0-30V)

I have a Proportional solenoid valve that uses a 0-30VDC for control (opening the orifice) I only have capability to provide 0-5V or 0-10V. I need to control the valve using my PC. Is there any DC ...
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1 vote
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### How are the modern hydraulic cylinders very precisely controlled?

My guess is that they use brushless Motors that in turn powers the hydraulic pump. But there must be some kind of valve that could help in the process. Still the burning question is just by adjusting ...
1 vote
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### Valve advice for chiller test rig

I am in the process of designing a chiller test rig, of which a very simplified diagram would be (the quick coupling might just be replaced by a non-return valve): I am struggling to find the type of ...
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23 views

### Create low velocity pressure drop?

I need to create a variable 3-7 psi / 0.2-0.5 bar in a low density gas running through some piping. I can calculate the required Cv factor to do this with a valve would be in the 30-200 range. Looking ...
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### Liquid Rocket Plumbing and Instrumentation Diagram: Standards and Presentation

I'm working on a team to build a liquid sounding rocket as a school project. We need to present our plumbing and instrumentation diagram, but we are butting heads on what program and standards we ...
1 vote
43 views

### Build Device for Emitting Weak Air Bursts at Specified Frequency

I'm a neuroscientist interested in building a device to replicate the following study. https://www.nature.com/articles/s41598-018-24924-9 Essentially, they sent air through a nose catheter to ...
1 vote
24 views

### Is this Proportional Electro-pneumatic valve a direct replacement for other valves listed?

In the midst of trying to redesign the pneumatic subsystem of a combined system, I'm at the point of validating a new valve would serve as a direct replacement. The reason for the redesign is an ...
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1 vote
46 views

### Is there a male and female valve that is closed until connected together?

I'm trying to make a quick release male and female connector similar to the one shown here. One connector is attached to the bottom of a container filled with liquid. When it is not connected it is ...
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1 vote
980 views

### What is the point of this valve that only allows air in and not liquid?

I'm looking at googles mocktails maker. And it puts 2 holes in a container. 1 hole is connected to a pump that will take water out and the other connects to a backflow prevention valve that only ...
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### Liquid phase gas flow through valve

I have been trying to figure out how to calculate the required dimensions for liquid phase gas through a solenoid valve. Many companies (Swagelok, Bürkert, Asco) provide "Flow coefficient calculators" ...
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265 views

### Reduce 180 degree rotation to 90 degree rotation without gears

I am actuating a small ceramic rotary valve with a cheap mg996 servo motor. The valve has a 90 degree max rotation from fully closed to fully open. Currently I have the servo shaft directly coupled to ...
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1 vote
277 views

### Check valve with precise cracking pressure

I have two containers of air, one at 100 kPa and rising, the other at 30 kPa and decreasing. I need a valve that lets air through when the pressure difference is >70 kPa. Where would I find a valve ...
279 views

### Typical tolerances for valve lift using a camshaft?

I am working on a linear actuator for a valve. Wondering if anyone out there can point me towards the tolerances that are used for valve lift in a typical internal combustion engine using a camshaft?...
1 vote
114 views

### Why does the water pressure initially drop then stabilize when pressure testing a valve?

Sometimes the dropping goes on so long(10-15 minutes) that the test is thrown out and the valve is opened and filled with water for a longer period of time. Pressure testers claim that it is because ...
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### Deflection of a stack of disks under applied force/pressure

I'm trying to calculate the deflection of a stack of metallic disks, when subjected to a force. In the case of the figure below, representing a valve for a shock absorber, the force is due to a ...