Questions tagged [valves]

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20
votes
1answer
456 views

Sizing a pressure safety valve for two-phase flow

I understand that valves in two-phase vapour / liquid were sometimes sized by considering the required vapour and liquid flow rates separately, and then adding the results together. But this is now ...
7
votes
1answer
246 views

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

Supposedly a Tesla valve will impede fluid or air flow in one direction whilst allowing flow to move freely through the valve entering from the opposite direction, without using any moving parts. Also ...
5
votes
2answers
185 views

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

The specific example I have in mind is a car tire with a small leak in it. As the pressure increases, does the outflow of air increase linearly, i.e. $v\propto P$, or does it have some more ...
4
votes
2answers
60 views

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 ...
4
votes
4answers
194 views

Which components to use for a CO2 gas storage?

I have a CO2 production for my aquariums (currently 2, but the solution should be extenable to - let's say - 5) based on fermentation of bio mass (CO2 is used as fertilizer there) which consist of a ...
4
votes
2answers
4k views

Solenoid valve pressure drop

I'm designing a solenoid valve for an automated irrigation project that I'm working on. After having looked at some designs, I have a question. For most of the designs I've seen, the orifice is ...
4
votes
1answer
32 views

Is there a (sort of inverse security) valve which opens if one connected side has a pressure below a certain value?

Security valves with two connectors open if the pressure exceed a value x +/- tolerance on one side. I'd like to know if there's a mechanical valve which opens if the pressure on one side sinks below ...
4
votes
1answer
15k 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: ...
3
votes
3answers
373 views

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

I am trying to come up with a way to restrict beer flow using a valve that does not cause foam. I have found that a solenoid valve causes a change in the direction the beer must flow and this sharp ...
3
votes
2answers
238 views

What type of liquid flow control could this device use?

I am trying to figure out what kind of device is being used to stop and start the flow of liquid inside this device. Below is a link to the device. It looks too small to be a solenoid or a pump. How ...
3
votes
1answer
443 views

What is this plumbing apparatus?

This device is about five feet tall. It is located in a ground-floor alcove in the exterior of a commercial building on a public street in Santa Monica, California. Each of the chained manual valve ...
3
votes
1answer
186 views

Service Life of a Flashback Arrestor

First of all, I would like to know about the service life of a flashback arrestor. In my laboratory, I got three flashback arrestors {WITTgas RF53N(1/4”NPT-F), Brass} from the ex-students who used ...
3
votes
1answer
404 views

Automatic siphon above max height

The soil in my area has a very thick clay content (apparently left behind by glaciers, damn ice age). Because of this drainage in my yard is horrible. I've put in some underground drainage (french ...
3
votes
1answer
141 views

How to evaluate solenoid valve specifications

I need to replace a solenoid valve, and I need help in identifying the specifications that I should check for an equivalent replacement. This is a picture of the valve itself: Click for larger image ...
3
votes
0answers
45 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 ...
2
votes
2answers
134 views

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 ...
2
votes
2answers
15 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 ...
2
votes
1answer
41 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 ...
2
votes
1answer
69 views

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 ...
2
votes
4answers
392 views

Why to avoid low and high fluid velocities in hydraulic systems

I know that different geometries of piping, orifices etc... have different critical Reynolds values. If the value is exceeded laminar stream will turn to a turbulent form which causes a variety of ...
2
votes
1answer
51 views

What valve to use to divert incoming air from a pipe to another pipe stream?

There's an 4 inch exhaust stream that's emitting air at 2000CFM, I want to divide the exhaust in a 'Y' kind of outlet with two pipes. If State 0- Exhaust out through one pipe. If state 1- Exhaust ...
2
votes
1answer
2k views

How strict is the direction of air flow in a single direction pneumatic solenoid valve?

I am currently designing a small pneumatic system that pumps air into an airbag, holds the air in, then releases it to the atmosphere. Each pump in the system actually feeds two sets of airbags and ...
2
votes
1answer
245 views

Fluid dynamics: valve and pressure drop

I have a question regarding valves: Let's assume a district heating system where you want to control the mass flow in a sub-station with a valve. Is (in normal cases) the diameter of the valve (fully ...
2
votes
1answer
1k views

Valve for mini CO2 gas canister?

I am in the process of helping my son design a sort of model of the Bloodhound SSC car for his school project, using balsa wood, model aircraft wheels, etc... It doesn't have to a like of like, but ...
2
votes
1answer
76 views

Device to remove condensate, without creating a hazard (EX) zone

I have gas pipeline with biogas, low pressure - approx 40mbar over atmosphere. I want to remove a small amount of condensate, inside a building, without creating an ex-zone. Small amount: I honestly ...
2
votes
0answers
48 views

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" ...
2
votes
0answers
382 views

Best types of valves for dirty services

I've just started to learn Gate, Globe, Ball, and Butterfly valves. I'm thinking about "dirty services" now. Which types of valves are most suitable for dirty services, and what characteristics ...
2
votes
0answers
79 views

What specific characteristic of proportional solenoid valves makes the flow to current behavior quadratic?

If experimental data is obtained from a proportional solenoid valve, specifically flow vs current (assuming inlet pressure is constant), the fit is nearly quadratic in nature. Andersen's Analysis and ...
1
vote
3answers
84 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 ...
1
vote
1answer
1k views

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 ...
1
vote
1answer
155 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 ...
1
vote
1answer
4k 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 ...
1
vote
1answer
25 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 ...
1
vote
1answer
43 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 ...
1
vote
2answers
462 views

How much is too much control valve cycling?

In a textbook on process controls, I read that when tuning a controller there must be a balance between performance and excessive control element cycling. My question is, what corresponds excessive ...
1
vote
1answer
79 views

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
1answer
22 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 ...
1
vote
1answer
38 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
1answer
602 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
1answer
168 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 ...
1
vote
1answer
64 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 ...
1
vote
2answers
46 views

Can I make check valve in simple workshop?

I need a check valve ( one way valve ) for my project which has less actuation force (IDK real term. shouldn't require high pressure for inflow of fluid) and I searched in market for the valve but ...
1
vote
2answers
480 views

Water valve for over 120C temperature

I am making a project where i need to put a water valve below the tank and then need to open it automatically but the problem is that already available brass electric valves aren't good enough to ...
1
vote
1answer
65 views

How can I build a electronically controlled valve for a 1/4 inch tube

I'm looking for a practical efficient way to open and close a 1/4 inch gravity fed hose. Initially I was thinking of using a Solenoid, but can't find anything suitable. My second thought was using a ...
1
vote
2answers
949 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 ...
1
vote
0answers
35 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 ...
1
vote
2answers
245 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 ...
1
vote
0answers
19 views

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 ...
1
vote
0answers
18 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 ...
0
votes
2answers
233 views

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

In my exam, I was given 2 options to design a process. Assuming a saturated liquid coming out from the separator, A) should the stream pass through a valve to reduce pressure, then to heat exchanger ...