Is my compressor drain valve safe?

[balane]

I hated dealing with the old petcock on my compressor. I just put this together with parts from Lowes. The valve was actually in the air compressor section of the tool department. The other parts came from the plumbing aisle and I am only hoping they're adequate for compressed air. The horizontal piece is 6" long. Right now it's all tight and not leaking. The compressor is a 22 gallon 5HP Husky.

Will this be acceptable?

While we're on the subject, my compressor kicks on maybe twenty times a week, I don't use it much at all and when I do it's usually for something quick like blowing the dust out of a computer or taking off wheels. Am I OK to drain it once per month or should I just leave it open all the time?

 

[von zipper]

Good ? I want the same 4 mine!

 

[MrMark]

Looks perfect.

You only need to drain the moisture out of it after it has run and the air has had time to cool. If you run it and leave it alone then the air will cool and the moisture will condense and collect in the tank. Drain it then. If you don't run the compressor again then there will be no more hot moisture laden air injected into the tank to cool and drop moisture so it will be OK for the drained tank to sit under pressure.

 

[MrMark]

BTW, why is your compressor kicking on 20 times a week if you don't use it??

 

[balane]

OK, thank you. So since mine is basically always cooled down do you recommend I just leave the valve open until I need it?

BTW, what does it mean when it stutters to drain? It will exhaust rather powerfully for a while, then do nothing but after 20 seconds or so it will start to blow hard again, then pause, then blow again, etc. until eventually it stops blowing. Is this indicative of an issue? I'm visualizing a piece of rust sitting in the bottom drain port not letting air leave consistently.

 

[balane]

BTW, why is your compressor kicking on 20 times a week if you don't use it??

Guess I didn't phrase that right, I use it enough so that it kicks on and recharges about 20 times per week, meaning that's all it will cycle under use during a week... on average and that's a very rough estimate. It won't kick on at all if I'm not using it.

 

[MrMark]

Guess I didn't phrase that right, I use it enough so that it kicks on and recharges about 20 times per week, meaning that's all it will cycle under use during a week... on average and that's a very rough estimate. It won't kick on at all if I'm not using it.

That's a fair amount of cycling. You should drain it before EVERY use to avoid water blowing out from the tank.

 

[balane]

OK, great, thanks. Good to leave the valve open when it's empty or shut it after it drains completely?

 

[MrMark]

OK, thank you. So since mine is basically always cooled down do you recommend I just leave the valve open until I need it?

BTW, what does it mean when it stutters to drain? It will exhaust rather powerfully for a while, then do nothing but after 20 seconds or so it will start to blow hard again, then pause, then blow again, etc. until eventually it stops blowing. Is this indicative of an issue? I'm visualizing a piece of rust sitting in the bottom drain port not letting air leave consistently.

On your first, just leave it under pressure. There is no need to drain it down and waste all that electricity. All you need to do is blip the valve open for a second or two a couple of times to exhaust the water in the bottom of the tank. That is also what an auto drain does. Some auto drains will blip the drain every cycle.

On the second question, the stuttering is NORMAL. Liquid water is moving around and managing to block the exhaust port as the air gets to low pressure.

 

[chrommagman]

that is a great drain set up!! it will be loud it you drain the tank wile there is air still in it (over 50 psi) but it will work just fine

 

[balane]

that is a great drain set up!! it will be loud it you drain the tank wile there is air still in it (over 50 psi) but it will work just fine

Loud it is. When I drained it for the first time, I was demonstrating it to my wife at the same time, she high tailed it out of the room immediately.

Thanks for all the advice on this guys.

 

[Frank The Plumber]

I'd put a down turned 90 on it so it doesn't blow debris at you at 120 psi. That would be safest.

 

[fr0mastaj]

Like Frank said, I would put a 90 street elbow at the end of that. Thats what I did.

EDIT: Here's a quick pic i just took

 

[balane]

I thought about that when I was putting it in, I didn't think about a projectile but just to aim the air blast at the floor. I'll pick up a ninety next time I'm in the hardware store.

 

[ZRX61]

I'd put a down turned 90 on it so it doesn't blow debris at you at 120 psi. That would be safest.

Not standing in front of it would have the same effect..

 

[MrMark]

Like Frank said, I would put a 90 street elbow at the end of that. Thats what I did.

EDIT: Here's a quick pic i just took

I think that would be worse than just straight out. There is no space under the 90 and anything that comes out (the water) would blast everywhere when it hits the floor.

If you just throw a towel down in front of the valve straight out it works the best. There really is very little danger from that small orfice down low like that.

 

[AndrewHR]

I have my compressor next to an exterior wall so i ran the copper drain pipe through the wall so no moisture. debris kicking up etc in my workshop

 

[DrunkSmurf]

I have my compressor next to an exterior wall so i ran the copper drain pipe through the wall so no moisture. debris kicking up etc in my workshop

x2 Only I used some old flexible fridge water supply line I had lying around.

 

[bad_idea]

i have the same drain setup on my compressor. i further agree not to completely drain the tank after use, it is a waste of money. let the air cool, then open the valve long enough to let the water out and then shut it again. i have an empty quart oil container that i put over the end of the valve to blow the water into. that is oily water coming out of the tank, and it will make a mess on the floor.

i know, i know it shouldn't be real oily water. if it is overly oily then u need new rings, but even a fresh rebuilt compressor will have a small amount of oil getting by the rings.

 

[dadsEH]

OK, thank you. So since mine is basically always cooled down do you recommend I just leave the valve open until I need it?

BTW, what does it mean when it stutters to drain? It will exhaust rather powerfully for a while, then do nothing but after 20 seconds or so it will start to blow hard again, then pause, then blow again, etc. until eventually it stops blowing. Is this indicative of an issue? I'm visualizing a piece of rust sitting in the bottom drain port not letting air leave consistently.

the air is under high pressure and when you open the tap slightly it escapes under high velocity but with low volume and it expands rapidly causing severe cooling and moisture to collect and freeze in the outlet side of the tap tube.
eventually the outlet freezes over , air stops flowing for a few seconds and the ice plug melts and is blown out by the pressure behind it allowing air movement to begin again.

This is the basics of your air conditioner in a car. The refrigerant circulates as a gas in the system on the low pressure side before the compressor and on the high side of the compressor it becomes a liquid which is forced through a small oriface just in front of the evaporator and it becomes a gas again which is super cold and causes air to be cooled as it flows over the pipes holding the gas. The compressor uses a thermostat inside the evaporator to sense temperature and regulate the flow of liquid ....too cold and it can cause the whole system to turn into A BLOCK OF ICE!! This is why your compressor turns on and off as you drive.

 

[MoonRise]

To the OP (balane),

If the pressure ratings on the pipe, elbow, and valve are 'adequate' for the pressure of your compressor, then you are good to go.

As to the horizontal pipe vs a down-turned 90 elbow, I have a horizontal pipe and just pay attention to where it is pointed when I open the drain. A down-turned 90 will blast water and floor debris all over the place in all (random) directions. I find it easier to just watch where the horizontal pipe is pointing.

As to the air flow 'stuttering', as the previous post says (by dadsEH), it is due to the expansion cooling of the compressed air expanding (rapidly) from whatever pressure the air in the tank is at to 14.7 psia (atmospheric pressure) and thus cooling so rapidly that the water in the pipe/valve freezes. When it then melts in a few moments, the air (and water) flows again and freezes, and the cycle repeats. See next paragraph:

As to how often to drain, I try to drain for a few seconds after every 'refill' of the air tank (pretty much just like and auto-drain wouild do). This way there is only a small 'squirt' of water (probably less than a teaspoon, but when it it propelled by 100 or 150 or 200 psi of air pressure it seems like more than that ) If the pump is working hard and the tank is warm, I'll wait for things to cool down before 'blipping' the drain valve (warm tank and warm air will hold water in vapor form, I want things to cool down as much as possible so the water vapor condenses as much as possible into liquid water that I can then squirt out via the drain pipe/valve).

Speaking of water condensing out and pipe and such, pay attention if you have the system in a place where it may be exposed to freezing temperatures in the winter. BTDT, I must have forgotten to drain the system after filling tires in the winter or such, and the compressor is in the garage. Winter time cold temps + water in the low-spot drain pipe = burst pipe piece from the water freezing and expanding and splitting the seam on the pipe. Luckily just a few $$ and a few minutes to replace the small piece of pipe.

And as said, you don't drain the air tank fall the way down to 0 psi, just 'blip' the drain valve for a few single seconds. You payed to compress that air, don't throw it out (so to speak).

 

[plinker]

Like Frank said, I would put a 90 street elbow at the end of that. Thats what I did.

EDIT: Here's a quick pic i just took

I have the same setup on my compressors. A small pan will work for catching the water.

I only crack the valve open enough to let whatever water is in there out.

Word of advice;
If your compressor is in an unheated garage/shed, let the air out when your done with it, as any water will freeze and crack the brass fittings. Then you'll have a nice leak like I did one time.

 

[lonestarky]

Glad someone addressed the expansion causing freezing at the plug for the 'stuttering during draining'.

Make sure you know what your pipe, fittings, and valves are rated for. If its not rated for the pressure, my personal opinion is don't use it. Most likely it will just leak. 1 out of 100 times it will fire something like a missile through a car window, or person.

I'd feel pretty silly if something broke, and right on the side of the package it said 'rated for 60psi' and I was trying to cram 155 psi through it even if I thought it would be ok.

I would drain until you stop getting water out of the tank. Water in a metal tank is never a good thing, Under pressure or not. I'll use up all the air I need without the compressor switched on, and let the drain line stay open to completely bleed the system.

 

[chrommagman]

So I have a Q,

seeing as there is still a lot of water in my tank and I can't get it out I was going to take out that large fitting that goes in the the tank so that I would have a larger exit for the water.

is this a smart or stupid

 

[mdbeck1]

...As to the air flow 'stuttering', as the previous post says (by dadsEH), it is due to the expansion cooling of the compressed air expanding (rapidly) from whatever pressure the air in the tank is at to 14.7 psia (atmospheric pressure) and thus cooling so rapidly that the water in the pipe/valve freezes. When it then melts in a few moments, the air (and water) flows again and freezes, and the cycle repeats.
...

I haven't had my new compressor very long but I haven't had this problem yet. Of course the ambient temperture in my garage for the last month has been approximately 103F. Of course that might all change in four or five months when the temperature drops closer to freezing.

 

[Bruce4310TX]

On your first, just leave it under pressure. There is no need to drain it down and waste all that electricity. All you need to do is blip the valve open for a second or two a couple of times to exhaust the water in the bottom of the tank. That is also what an auto drain does. Some auto drains will blip the drain every cycle.

On the second question, the stuttering is NORMAL. Liquid water is moving around and managing to block the exhaust port as the air gets to low pressure.

Yep that works great used mine like that for at least 20 years.

 

[onething]

I usually drain my tank at the end of use because it may be many days before I use it again. When I first restart the compressor, I leave the drain open and usually blow more water out. I lost my old tank to rust.

 

[Milton Shaw]

If you put a lawnmower muffler on that,it will be a lot quieter. I used one on my outlet and its a lot better. I have the muffler pointed down so it doesn't hold water but does quieten the air flow greatly. I used the long Briggs style that's 1/2" pipe thread. My compressor is a 5 hp 60 gallon that had a 1/2" drain fitting that was impossible to reach. I piped it up and out of the building with a valve I can reach without getting on my knees.

 

[Hosalabad]

OP, this is exactly what I did on my compressor.

 

[balane]

Since this was resurrected and now a month and a half old I can comment after using it a while. I would never go back to the original valve. It's working flawlessly and the seal is still 100% Can't believe I put up with the old valve on the bottom for so long. I'm glad it failed.

 

[CV Street Rod]

Have an auto tankdrain on mine. You set how often it spits, works good. Also bent a piece of conduit and bolted it to the bolts holding compressor to floor. It works as a bumper for valve, park my jack by compressor. Also put about 3' chunk of old air hose on to valve exhaust port and run it into gal antifreeze container. Empty container once a month or so.

 

[Charles (in GA)]

The other parts came from the plumbing aisle and I am only hoping they're adequate for compressed air. The horizontal piece is 6" long. Right now it's all tight and not leaking. The compressor is a 22 gallon 5HP Husky.

Will this be acceptable?

I would not expect any problems from the pipe not being able to carry the pressure. The pipe is most likely designed for 150 psi working pressure max. Brass is pretty sturdy.

The issue I have is that you will probably have the long pipe break off from vibration of the compressor, It will crack thru the threads. Either the fitting into the tank, or the pipe into the fitting. It needs some support.

Here is my compressor base, I built when I bought the compressor in 2003. The valve is supported by a pipe support attached to the leg, on the outside end of the valve. The hose allows me to stick it in a bucket and run out the water. Water runs steady, then when the air starts coming out, it spits real violently, even if the valve is just cracked open. Nature of the beast.

Charles

 

[Charles (in GA)]

So I have a Q,

seeing as there is still a lot of water in my tank and I can't get it out I was going to take out that large fitting that goes in the the tank so that I would have a larger exit for the water.

is this a smart or stupid

Very unlikely you will get that bushing out of the tank. As was discussed in another thread, it many times takes heat, and long pipe wrenches to get them loose.

Charles

 

[oldtractors]

Safe? Sure, but it is brittle. I have the same setup on my wheeled compressor. The one or two times I move it a year (for air at the far end of the property), I seem to catch it on something and break it off. I makes a big noise when you do that. It also takes an easy-out to pull what is left of the elbow out of the tank. Moral is, don't trip over it and you will be fine.

 

[BJ42LX]

So I have a Q,

seeing as there is still a lot of water in my tank and I can't get it out I was going to take out that large fitting that goes in the the tank so that I would have a larger exit for the water.

is this a smart or stupid

So, just how fast do you want to drain the water from your tank?