Compressor automatic drains

[pcm81]

Greetings.
I am looking for some real world education about compressor tank auto drains. Already watched a bunch of videos, so interested in additional information.
As far as i can see there are 4 types of drains:
1. electric
2. pneumatic that drains when pressure is released to 0. This is what is often used in cheaper regulator dryer combos.
3. Pneumatic that drains when a certain water level is reached
4. Pneumatic that cycles periodically and has parasitic effect on compressor power (uses up like 0.3 cfm).

My compressor is not anywhere near a 120V outlet, so electric is out of the question unless it is 220 and i wire it into compressor plug wiring.

I bought and am playing with group 4 style drain now; just have it temporary connected to drain valve via 1/2 inch hose; so its just sitting on the floor next to compressor. I bought on Amazon: Pneumatic auto drainer for air compressor tank 1/2'' NPT drain valve Compressed air dryer with metal case connecting directly electricity free operation pressure up to 20 par ADTV-69

I didn't initially realize that it would be constantly going off, like once per second. I am now looking at category 3 designs:

Brianna Auto Parts - 284412 - Automatic Drain Valve - 12 Volt Heater for Heavy Duty Big Rigs​

This one seems to only go off when it fills up with water. May be it will even fit under my eastwood QST 30/60 compressor tank??? have not measured.

Anyhow, what are your thoughts on application/reliability etc of the 3 categories of pneumatic drain valves?

I guess one advantage of the category 4 unit like what i got is that it will release all pressure from the system; i just wish it would go off like 10x less often than its slowest setting is.

 

[Vecair]

I had a auto drain on my IMC and it lasted about a year and a half. Came from McMaster.

 

[pcm81]

What type was it? did you like it? I am trying to learn real world lessons about the differences of the types i described.

 

[Bill D]

The standard electric timer ones come in 120,220, 230, 24 and 12 volts. How long and how much do you run your compressor? I do not use mine much. I have it wired to power on only when the motor is powered and running. It puffs a little on each startup and vents every 15 minutes of run time after that. I should add a pushbutton to vent it when I end the day.
Bill D

Amazon.com

 

[pcm81]

I usually run for anywhere between 15 minutes and couple hours.
I was looking at the electric ones earlier, but was only seeing the 120V versions on Amazon, which is not an option for my compressor location. A 220V version should probably work. Seems like $20 is pretty cheap though; are they reliable?

 

[john.k]

Trucks use auto drains on the air tanks ,and they are probably much cheaper from a truck supply than an industrial hardware house......The last Sullair compressor the sandblasters bought used to piddle water continuously while it was working ,with no loss of air ......Sullair stuff is expensive ,though.

 

[pcm81]

One thing i was also reading up on is the size of the opening and clogging. The pneumatic one i got now is 1/2" opening. Do these electric solinoid ones work ok for scroll type compressor, which are not oilless; so there may be some oil in the tank...

 

[dkmc]

I should add a pushbutton to vent it when I end the day.
Bill D

?? There's a test button right on it, push that at the end of the day.

 

[CarbideBob]

No mention above of the basic float style drain?
That is what is on my tanks. Works well, does need to be cleaned every 4 or 6 years.

 

[john.k]

The float style were generally called 'steam traps' ,and they were fitted to the big air tanks .....they never worked for more than a few months from new ,and I used to drain a hundred gallons of water every morning by a manifold I set up and a manual operated gate valve .

 

[pcm81]

No mention above of the basic float style drain?
That is what is on my tanks. Works well, does need to be cleaned every 4 or 6 years.

I guess my category 3 would be the float type you are referring to... i just don't know if they are more or less reliable than pneumatic or electric... Hence this thread...

 

[pMetal]

I have used both the electric timer types (venting every 45 minutes or so), and also the float drain types.

The float drains tend to clog and go bad after a while, but you can definitely get a few years of good service from them.

The electrics seem pretty reliable, although they are very loud when they vent since they blow at full pressure. Clearly the electrics use much more air than the float drain type.

FYI, for your electric needs, since you are not near a 120V outlet, you should be able to take 1 of your hots from the 220V circuit, and make a 120V circuit right at your compressor. If your compressor is single phase, then you're in great shape - you already have a 120V hot leg, a neutral and a ground. If you have 3 phase (which has no neutral), you could technically use the ground as your neutral, although that is not a proper thing to do.

 

[pcm81]

I have used both the electric timer types (venting every 45 minutes or so), and also the float drain types.

The float drains tend to clog and go bad after a while, but you can definitely get a few years of good service from them.

The electrics seem pretty reliable, although they are very loud when they vent since they blow at full pressure. Clearly the electrics use much more air than the float drain type.

FYI, for your electric needs, since you are not near a 120V outlet, you should be able to take 1 of your hots from the 220V circuit, and make a 120V circuit right at your compressor. If your compressor is single phase, then you're in great shape - you already have a 120V hot leg, a neutral and a ground. If you have 3 phase (which has no neutral), you could technically use the ground as your neutral, although that is not a proper thing to do.

Thanks for suggestion about the 120. I thought about doing just that but am hesitant. I am picking up the 240 from my 50A outlet behind the kitchen stove (proper 50A Y cable with nema 14-50 outlets) and was not sure if being a kitchen outlet the 50A breaker for it would have some fancy GFI circuitry that compares current in 2 hot legs to check for ground leaks, just like gfi checks hot and neutral.

EDIT: also the eastwood QST30/60 comes with 3 wire cable, so its a nema 6 style, 2 hots and a ground; no neutral. Basically i'd have to run a new cable to add a neutral and a nema14-50 outlet; which i can do if that is the only option... but was hesitant unless the electronic ones are in fact best option.

 

[CarbideBob]

The float drains tend to clog and go bad after a while, but you can definitely get a few years of good service from them.

Define a few years. Three pumps here during demand. Well over 20+ years on the float drain valves.
It is not just the tank. What to do downstream for drip legs and drains? I get lots more water there.

 

[D Nelson]

I usually run for anywhere between 15 minutes and couple hours.
I was looking at the electric ones earlier, but was only seeing the 120V versions on Amazon, which is not an option for my compressor location. A 220V version should probably work. Seems like $20 is pretty cheap though; are they reliable?

Split the 220 circuit and get your 110 volts
Don

 

[rons]

Float types rely on a float with residual water that eventually rises until a release point.
Until the release point the residual water is just sitting there. All you have to do is disassemble a filter or tank that uses one.
The area around the drain is corrosion city. I don't use those things any more.

 

[Davewitt]

We have used a 110 volt electric one for several years. It is set to blow off every 45 minutes, then we plugged it into a timer so it only works when nobody is there to hear it. As others have mentioned, split 110 off the 220, not a big deal.

 

[technocrat]

I usually run for anywhere between 15 minutes and couple hours.
I was looking at the electric ones earlier, but was only seeing the 120V versions on Amazon, which is not an option for my compressor location. A 220V version should probably work. Seems like $20 is pretty cheap though; are they reliable?

I don't use much air at all, so I just run a very small leak in the bottom tank drain valve. It uses a tiny bit of extra air, removes the moisture and leaves me with an empty tank and lines after 6 or 8 hours.

 

[pcm81]

I don't use much air at all, so I just run a very small leak in the bottom tank drain valve. It uses a tiny bit of extra air, removes the moisture and leaves me with an empty tank and lines after 6 or 8 hours.

After messing with the pneumatic valve i listed above; this is basically also what i have. It bled my tank empty in like an 30m or so.

 

[pcm81]

Pneumatic types rely on a float with residual water that eventually rises until a release point.
Until the release point the residual water is just sitting there. All you have to do is disassemble a filter or tank that uses one.
The area around the drain is corrosion city. I don't use those things any more.

This is what i refer to above as float type. The pneumatic one i have does not appear to have a float.