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Questions tagged [valves]

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0 votes
2 answers
88 views

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 ...
0 votes
1 answer
117 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 ...
0 votes
1 answer
43 views

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 ...
0 votes
1 answer
218 views

Displacement and force control with pneumatic cylinder

Good day, I was confronted with the task to develop a new controller for pneumatic cylinders. The control channels are displacement and force. A load cell is used to measure the force (analog signal). ...
0 votes
1 answer
25 views

Operating a latching 24V DC valve with non-reversible current direction signal

Most 24V DC latching valves require a reversal of the current flow direction to be able to switch between open/close states. However, is there a way to operate them with a signal that can only go 0V ...
0 votes
0 answers
18 views

Help identifying a source for medical/bioprocess rotational pinch valve

I am attempting to identify a type of pinch valve that I have seen used in a few different bioprocess and medical blood/fluid perfusion systems. The valve appears to be actuated by a stepper/servo ...
1 vote
2 answers
68 views

What would prevent me from using this valve for water?

https://www.kingstonvalves.com/product/ksv25cr-stainless-steel-asme-soft-seat-safety-valve/ Looking to use this for water instead of air. I haven't seen a good reason not to as the physics of the ...
0 votes
1 answer
39 views

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 ...
0 votes
1 answer
124 views

Automated valve for testing module

I work frequently with materials sensitive to oxygen and moisture, within a glove box. However, there are frequently times I want to move these samples from the glove box to a scanning electron ...
1 vote
1 answer
64 views

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 ...
0 votes
0 answers
22 views

Can the debris found in seawater compromise the sealing of a subsea check valve?

In the event of a subsea check valve opening and debris lodging in the region where sealing takes place, could that make the valve not close when it should? Would that happen to debris of any size? If ...
0 votes
0 answers
18 views

Why isn't my valve controller not providing sufficient amount of voltage to my fan?

We're using the valve controller below to control the speed of a (generic) fan: https://products.axiomatic.com/viewitems/valve-controls/can-to-4-outputs-valve-controller Problem: We're supplying the ...
0 votes
3 answers
77 views

Passive gas mixing valve that takes fixed ratio of gas from two different inputs

I am designing a device that requires a gas (air) valve that takes the same volume of gas from two different input ports IP1 and IP2. The output port OP will have lower pressure than both of the ...
1 vote
3 answers
2k views

Reverse float shutoff valve

I have an application that is drawing fluid from a reservoir via a standard dip tube. This application has a special requirement that once the fluid is depleted from the reservoir, the pump pulling ...
0 votes
0 answers
71 views

Normally open check valve

What I'm looking for is basically an always open check valve that closes at a certain pressure. ~5psi. The application is a breather vent that closes if the valve is submerged in water. Would a biased ...
0 votes
3 answers
72 views

What does 12CC refer to when talking about voltage?

Is it 12V with a connector? For example in the data sheet here: https://www.hydraulicmegastore.com/product/vcf12nc12cc/ Is this related in any way? (A DMP-12CC connector cable) https://www.monacor.com/...
4 votes
1 answer
18k views

LO/LC, CSO/CSC Valve Definition

Does any one here know of an authoritative source (ASME, ISA, NFPA, OSHA, etc..) that gives a definition for the following in one of their standards or codes and the number for that standard or code: ...
0 votes
1 answer
301 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 ...
0 votes
0 answers
50 views

Why no lever tools were used during manual valve opening attempts in Fukushima Daiichi?

I watched a PBS documentary https://youtu.be/qRKScRgsUaE and Netflix series about this accident. Both show very slow and strenuous attempts to open a valve manually. Why there was no use of level ...
1 vote
3 answers
52 views

Volume multiplying hydraulic pressure reduction unit?

I'm tying to figure out what something is called, assuming it exists at all. If I knew what to search for, I'm reasonably sure I could figure out which part would be suitable for the application, but ...
1 vote
1 answer
2k 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 ...
0 votes
2 answers
128 views

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 ...
0 votes
1 answer
27 views

How to prevent liquid backflow when pumping an upside-down liquid container with air to pressurize it?

I'm trying to design a system that will have glass bottles upside down filled with liquid. They will be pressurized via a bulkhead air input and will dispense through bulkhead liquid output. Here is a ...
-1 votes
1 answer
242 views

How does the hydraulic valve system work in excavators?

There are many types of valves used in excavators. Two are important: the main valve and the pilot valve. Is the pilot valve is controlled by the operator and the main valve is controlled by the pilot ...
0 votes
0 answers
39 views

Do 6/3 proportional valves like this exist?

Like a directional valve but used to select either pair of supply and return. Could be done with two regular 5/3 valves, but it would be nice to use only a single valve. Does something like it exist?
2 votes
1 answer
45 views

Improving O-Ring/flapper valve injection mold ->non-engineer

I make specialized flapper valves that are similar to O-Rings. The current model uses aluminum sheets as base disks that adhere to the rubber (2 part urethane). The rubber is poured into the waxed ...
0 votes
1 answer
188 views

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 ...
0 votes
2 answers
328 views

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/...
0 votes
1 answer
53 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?
1 vote
1 answer
2k 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 ...
1 vote
2 answers
70 views

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 ...
1 vote
3 answers
9k views

Can PWM be used to control the flow of a solenoid valve?

Most cheap pump can achieve, according to the Amazon page, around 5 PSI and I would need something a way higher that can still be controlled. I have this solenoid valve. Can I use pulse-width ...
0 votes
0 answers
41 views

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 ...
1 vote
2 answers
371 views

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 ...
0 votes
1 answer
65 views

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 ...
0 votes
1 answer
39 views

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 ...
0 votes
3 answers
114 views

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 ...
0 votes
1 answer
51 views

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 ...
1 vote
0 answers
40 views

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 ...
0 votes
2 answers
1k views

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 ...
0 votes
2 answers
32 views

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 ...
0 votes
0 answers
22 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 ...
0 votes
1 answer
32 views

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?
3 votes
2 answers
477 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 ...
0 votes
0 answers
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 ...
0 votes
1 answer
39 views

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
37 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
45 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 ...
0 votes
0 answers
40 views

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 (...
0 votes
2 answers
198 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{\...