2 Stage Air Compressor Help

[MaxThroughput]

Hey All, I took apart my compressor today because I found a concernable amount of oil leaving one of the cylinders. The compressor looks to be recently rebuilt, cylinder walls look damn near new and the pistons are nice and shiny. Reed valves look to be in good condition, so now i'm wondering if it's just set up wrong.

The Compressor is a tf28 from Cambpell Hausfeld which I figured out after diligent internet research.

Question #1 - What is the line for that goes from the crank case to the valve cover? It seems to be putting oil into the air. Can I block this off? I noticed that not all compressors have this.

Question #2 - How can I replace the check valve with a new 175psi one? This compressor is rated for 175psi and the current valve just blew, maybe from age, but my switch was probably set too high.

1: http://i.imgur.com/0VNmpG6.jpg

2: http://i.imgur.com/pqDPC7X.jpg

2 continuted: http://i.imgur.com/EGTcpgU.jpg

Thanks.

 

[930dreamer]

Please resize your pics.

 

[Bondo]

Please resize your pics.

Ayuh,... Unreadable as it is,...

Delete the pictures, 'n just post a link to 'em, if ya can't figure out how to resize 'em,....

 

[Heavymetalmechanic]

The line from the crankcase to the heads is for the unloader valves and is likely the source of the oil. There is a shuttle/check valve in the cover on the end of the line attached to the crankcase, it controls the unloader valves on the top of the heads. They get gunked up and stuck, allowing oil to be forced into the unloader valves. Open it up and clean it, there is usually a breather screen that needs to be cleaned or replaced. Also disassemble the unloader valves on the oily piston, the diaphragm valve is likely cut or punctured.

Edit: after looking at the pics again I may be incorrect about the line, I'm basing my thoughts on a Quincy. You should turn down the pressure as well if you blew the rupture disk safety valve. There should be a spring loaded relief valve on there somewhere too, set slightly lower then that of the rupture one.

 

[MaxThroughput]

The line from the crankcase to the heads is for the unloader valves and is likely the source of the oil. There is a shuttle/check valve in the cover on the end of the line attached to the crankcase, it controls the unloader valves on the top of the heads. They get gunked up and stuck, allowing oil to be forced into the unloader valves. Open it up and clean it, there is usually a breather screen that needs to be cleaned or replaced. Also disassemble the unloader valves on the oily piston, the diaphragm valve is likely cut or punctured.

Edit: after looking at the pics again I may be incorrect about the line, I'm basing my thoughts on a Quincy. You should turn down the pressure as well if you blew the rupture disk safety valve. There should be a spring loaded relief valve on there somewhere too, set slightly lower then that of the rupture one.

The line goes directly to the head, there is no valve in the path. I already took it apart. The cylinders looked good and the head has reed valves, which were all intact and in good condition.

The valve that blew is in picture #2. The air was coming from the bolt with the two holes in it. This blew at about 160psi, the compressor is rated at 175 and the tank is well above that. It was working fine at this setting for quite a while, so I think the valve may need to be replaced. Where can I find a valve like this? It looks like I may need to replace the entire tee that holds the valve.

 

[Fixnair]

The line from your crankcase end cap is your centrifugal pressure release circuit. Inside the end cap is a fly-weight assembly which at rest is collapsed. Linkage from the fly-weight will force a valve in the end cap open, releasing the pressure from the compressor discharge pipe to atmosphere so the next time the compressor starts it will not start against a load.

When the compressor starts up, the RPM will increase and reach a point where the fly-weights will fling out by centrifugal force and allow the valve in the end cap to close. Thus closed your compressor will pump up the tank and when your pressure switch shuts the compressor off the cycle repeats itself.

The check valve prevents the air in the tank from escaping through the centrifugal release valve in the end cap when the compressor is shut off.

I don't know what those other devices you have pictured are.

The oil leaving your compressor and collecting in your tank can only be going by the rings/Pistons. Despite your cylinders "looking good", the only real way to tell us to disassemble the Pistons and measuring the amount of wear. Your cylinders will be a nominal size. By that I mean the diameter should be a stock size. Like 4-1/2" or 1-1/4". It won't be some unusual size carried out to several decimal places. If you measure your cylinders they should not be any more than .003" oversize. Same with your Pistons. Almost always this wear is responsible for oil consumption. Rings do wear out but cylinder wear is always associated with ring wear too.

With a pump that size you are going to spend more $ remedying the oil consumption than a new compressor will cost. Get a new pump or live with it.

 

[sberry]

Take the head off,,, run comp for 5 mins. Is oil pooling on top of the piston?

 

[MaxThroughput]

I'm not sure how much oil is leaving the compressor. The sight glass is at the full line, so it may be a very small amount. It does not seem to be consuming much oil at all. My concern was that I'm using this to paint, but I will invest in a quality oil/water seperator and hopefully not have to worry about it.

I also found a verticle 80gal tank for $100 locally, so i'm going to pick that up today and transfer my motor and compessor to it, hopefully using the safety valves that are included, bypassing my need to figure out what the hell is going on with mine and its weird configuration.

 

[Fixnair]

Make sure the safety relief valve on the new receiver is rated to relieve more CFM than the maximum capacity of your compressor and is not rated at a pressure greater than the maximum Allowable working pressure stamped on the vessels tag.
Your compressor will put out something on the order of 18 SCFM @ 125 PSIG.

 

[MaxThroughput]

Make sure the safety relief valve on the new receiver is rated to relieve more CFM than the maximum capacity of your compressor and is not rated at a pressure greater than the maximum Allowable working pressure stamped on the vessels tag.
Your compressor will put out something on the order of 18 SCFM @ 125 PSIG.

Thanks for this. I actually found out just that after calling a parts shop earlier today. I decided on a 200PSI valve. I'll double check it's CFM rating. My new tank is an 80gal upright Ingersoll Rand Pro. Not a bad find for $100 imo.

 

[Fixnair]

Score!

 

[MaxThroughput]

I bought my new check valve and safety valves. One thing that has me stumped is the hole in the side of the check valve. What is this for exactly? Can I just plug it? My check valve looks just like this one

 

[MaxThroughput]

I'll answer my own question here for anyone who may find this thread through google or just searching the forum.

The hole in the side of the check valve is for your unloader valve. You should run a compression fitting from this hole to your pressure switch. This will relieve the air in the exhaust line from the pump to the tank once the compressor turns off. Without this unloading, you'll have a surplus of compressed air in that line and it will put unnecessary wear on the pump as well as the motor when it turns back on.