Install 3/2 valves in a Y configuration?

by Paul Simmons
(London, England)

I would like to use a 3/2 valve in a Y configuration. i.e. compressed air source is continuous at the base of the Y, and then I can switch the flow into either of the two legs at the top if the Y.


I think this is a 3/2 type valve, but the schematic diagrams show the air flow differently.
Can I use a 3/2 valve like this or will there be pressure problems with internal pilots ?
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Paul, in theory, yes. It were me though, since with the 3/2 you would plumb to the exhaust, and have either the supply or cylinder ports plumbed to your application, I might opt for an appropriately sizes 4/2, since with a 4/2 you have one supply, two power (cylinder) ports and one exhaust.

I would plug the exhaust, and then know that I had full flow to either of the two power ports I wished to use at a specific time.

The 3/2 would probably work, but if the valves in question aren't too big, I'd go for the 4/2 with the plugged exhaust.

If, however, you are looking at 1/2" valves and up, either should work.

Cheers,

Bill

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Which type of valve?

by sabu
(india)

How should we know which type of valve is suitable for a particular function in a machine?
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Sabu...

Air valves are commonly ported with 2, 3, 4 or 5 inlets and outlets.

What you are trying to do with the air valve will often determine how many ports the valve for that application will have. The amount of air demand will help decide what size of air valve is required.

Start by reading the pages about air valves on this site. Then, understanding how they work, you can match the valve to the application. It is the application that determines what valve to use.

Bill

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Valve for a petrol compressor?

by jason
(england)

Hi

what type of valve do i need to run a petrol compressor

i want to build a petrol powered compressor, i have a 5.5hp engine and i know the pump that i want to use, but i need a manual valve that dumps (exhausts)the air when the tank is full at 150psi, and then cuts back in when the pressure drops to a certain level, but i don't want any electrics to run it.
thanks
jason
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Jason, the type of control you need is one that allows the engine to idle down when the tank is full, and throttles up the engine when the pressure switch calls for more air in the tank.

If you do an internet search for "compressor idle" and "throttle controls" as I just did, you will get a number of options for your gas powered compressor.

Cheers,

Bill

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Auto Drain valves for car washes?

Your document refers to auto drains as applying to industrial compressed air systems.

A question on a general petrol station site that supplies air to a carwash - pneumatic rams (cylinders) and controls - air driven dosing (metering) pumps etc. with a tyre gauge and air operated LPG valve - would this type of installation need an auto drain on the air receiver?

At this point the receiver is drained manually once a week by site staff and compressor is often poorly located distant from the main air user - the carwash - up to 50 metres away. Carwash is heavily used on the weekends. Size of compressor is from 3 to 10HP.
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Hello Ross.

Usually industrial compressed air systems are high volume compressed air users, and the need for auto drains becomes more important as a result, and the water generated can't easily be handled by a "once a week" draining.

Having said that, all compressors generate water. See this page:

www.about-air-compressors.com/water.html

to find out why if you're not already aware.

So, will your petrol station benefit from an auto drain on the receiver?

Simple answer is, yes.

Because, if any of the systems being supplied by that compressed air can be negatively affected by free water and water vapour condensing in them, ridding the system of water can only help.

Having supplied rams (cylinders) to car wash OEM's in the past, my recommendation would be to use stainless steel. Many OEM's will not, finding the cost of them prohibitive. Over time, mild steel cylinders will rust, the barrels will score, and cylinders will ultimately cease to function as compressed air bypasses the shredded seals inside the cylinder.

And so it goes with other equipment that degrades from water, dirt slurry, and varnish from compressor oils that reach that equipment.

Auto drains are recommended at the receiver, at drop lines from the main supply, and, depending on the amount of water reaching the equipment, even on the filters that you've installed just before that equipment.

See this page:

www.about-air-compressors.com/plumbing.html

for compressed air plumbing tips.

Long supply mains are very prone to generating lots of water through cooling and condensation from the hot compressed air out of the compressor.

Hope this helps....

Cheers.

Bill

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