moisture in unloader valve

[bran1har]

Hows it going everyone. I got an air compressor that I have been having a problem with lately. It seems that an excessive amount of moisture is getting in the unloader valve and it never unloads by itself, I have to flip the lever manually every time it finishes unloading. When it unloads it spits a ton of moisture out, you can see in the picture the water droplets on the side of the compressor. Also, now when the compressor shuts off, the mag starter makes a horrible sound like it is rapidly switching on and off right before it reaches 175 psi, I took the cover off and let it cycle and is could see the sparks in there right before it shut off. This is a lefoo furnas style pressure switch with built in unloader. I have copper line running from the check valve which has a port for the unloader on it.

Can I install a moisture filter inline or something because it is really annoying, everytime the thing shuts off I got to walk over and unload it and I do painting and the paint booth is 75 feet away so I cant doo this much longer. Also, i think im going to burn up my contacts in the starter. Any advice. Thanks.

 

[DekeT]

Are you getting a huge amount of water in your tank? Is the humidity in the location of your compressor really high?

 

[bran1har]

No, I get very little moisture in the tank, and the humidity is very low, im in CT. I really don't understand where this water is coming from.

 

[mech-tech]

How hot is the motor getting? Could it be getting hot enough to cause the unloader line and air inside of it to heat, then cool at the switch causing moisture?

 

[zkling]

IMHO your pressure tap (where the switch senses tank pressure to cutoff) is not in the best position. It usually is in a separate port on the tank not right off the output of the compressor like yours is. That way you are sensing tank pressure at a more stable temperature. Water is a byproduct of the compression process. Add in copper line you have and you basically have a condenser. Thus I can see why you have water issues.

One thing I would do is either move your compressor away from the wall or rotate it 90°. As you have it now I don't think the intercooler piping is getting the best airflow off of the pulley fins.

As for the mag starter chatter. I'd check the contacts to make sure they are clean. Make sure power is disconnected for this.

 

[fxgmech]

No, I get very little moisture in the tank, and the humidity is very low, im in CT. I really don't understand where this water is coming from.

To answer your last question first: Any time you compress air you also concentrate any moisture that's in it. The only way to totally stop it is to compress air with no moisture in it to start with. Not ea$y.

The moisture condenses to water and we can find it right after the place it cools to the dew point temperature. That place could be in the tube before your unloader control or at the exhaust port.

If your compressor is in a wet area it's going to be worse, of course. At my work we leave the comp room door open and even in humid weather that helps.

BTW: If your'e not getting much water from the tank drain it could be because the tank is staying hot while the system is under heavy use. Another good reason to cool it down if needed. The problem you're asking about is before the tank, though.

I think you will always get some water to your unloader and you just need to control it. Some ideas: Is water leaking from the purge valve into the electrical section? Can you extend the exhaust port to keep water away? Contacts and connections clean and tight? How's the compressor air intake filter doing? If it's restricted there will be a pressure drop and moisture may be turning to water droplets before it even gets compressed.

 

[bran1har]

Just to clear one thing up, the pressure switch itself is on a port off the side of the tank, the copper line is just for the unloader, it does not sense pressure. Also, even when the compressor is not run under heavy load, I always have this issue of moisture. Can I run a longer copper line to the unloader or have a little drain, or a moisture trap or something?
Also, how do I check the contacts on the starter and if they are dirty how would I clean them. I will say that it is a cheap starter from china I got real cheap on ebay. I think I paid like $70 new with shipping so its not really a quality model, I dont know if that would contribute at all to the chatter.

Another thing is that I don't even know if the moisture in the unloader is causing the issue of the compressor not automatically unloading. It may just be the contacts are dirty in the unloader. As long as the thing automatically unloads i'll be happy, regardless of weather the unloader spits water or not, i just thought maybe that could contribute to the issue.

Thank you all so much for your advice, I appreciate it.

 

[zkling]

Just to clear one thing up, the pressure switch itself is on a port off the side of the tank, the copper line is just for the unloader, it does not sense pressure. Also, even when the compressor is not run under heavy load, I always have this issue of moisture.

I think we are having a technical term mis communication. Can you post a few more detailed pics of the overall unit and plumbing routing?

 

[bran1har]

Ok, i took a few more pics. You can see the brass check valve coming from the pump, and on it it has the copper line running over to the side of the compressor where the pressure switch is. The pressure switch has a built in unloader valve so that is why the line runs from the check valve to the pressure switch. Also you can see on the unloader there is a red handle on the right side that you can use as a manual on/off and it will also trigger the unloader if you push it and that is what I have been using. Also, the grey box is the mag starter.

 

[zkling]

Ok, those pics help alot. It looks like you actually have two unloaders hooked up? One is built into the pump as a hydraulic unloader. That it should keep the valves and head unloaded until oil pressure in the sump is obtained, then close the valves so pressure can build.

The large brass piece between the compressor output and the tank looks like a check valve with a unloader tap. I think that is knida unnecessary and redundant on your setup, but I'm not sure the specs on that pump. The reason you are getting water out of your unloader/pressure switch tap is because the air is very hot and moist coming out of the compressor after cooler that copper line acts as a condenser. There are a couple things that you could do to fix that.

I don't understand the part where you say you have to manually actuate the unloader via the pressure switch. That should happen automatically. I wonder if the head unloader and check valve unloader are fighting one another.

 

[bonacker]

While not answering your question I do have a suggestion. None of the wiring on the compressor meets code and it would be prudent to wire everything correctly (proper wire size and type). If a fire occurred (God forbid) and the fire inspector/insurance adjuster saw that setup, it is possible an insurance claim would be denied. I was a firefighter for 27 years and I'm just saying.....

 

[bran1har]

There is only one unloader. At one pint it had a factory unloader not sure what type but it didn't work so that is why this one is hooked up. Im not sure what the line going to the head does, its probably from the original unloader. I can't buy parts for this compressor anymore because they went out of business and I said screw it like a year ago and just plugged the hole for the old unloader and bought a pressure switch with a built in unloader. This was like a year ago I put this new pressure switch/unloader on and it has worked great without issue for like 8 months of frequent use, so it is only no that the chatter issue has arose. And yes the brass thing with the unloader tap is the check valve.
The pressure switch has its own manual on/off lever and when you switch it to off, it will trigger the unloader valve.

Also, yes I know the wiring isn't up to code, I don't really know how to do it to code, so I use my best judgement. I know a lot about electronics and radios so I know the wiring is large enough gauge for the amperage but I just don't know anything about wiring things properly up to code. It should probably be in some sort of sheathing or something I don't really know I just used extra wire I had from another job to hook this thing up. I should look into it and redo it at some point.

Thanks for the concern about the wiring, I'm glad you are looking out for me, Im going to ask my friend that is an electrician to look at it and tell me what has to be changed.