Extra outlets on compressor pump

[thinmac]

I just picked up an older Speedaire two cylinder compressor pump. In addition to the 3/8" outlet ports, each cylinder also has a 1/8" outlet. I found some info on the pump and it only mentioned the 3/8" ports.

Anyone have an idea as to what the extra ports are for? Seems like they wouldn't have put them on there if there wasn't a good reason. Any reason I shouldn't just plug them and use the main ports?

 

[kunkernator]

Spark plugs? LOL...

But seriously.... Where exactly is this output? Is it in the bottom, or the top of the pump?

If it is in the bottom, it could be for venting displaced air in the oil pan.

I do not know exactly, but some pumps have the pistons connected in what is called "two stage", it could be for this.

It could be a lot of things. I am just kinda thinking out loud.... I am sure someone knows the exact answer.

 

[Charles (in GA)]

Eighth inch ports in the heads are for plumbing for a head unloader for starting. Your compressor may have an unloader plumbed in somewhere else, above the tank check valve.

Charles

 

[Jim Johnstone]

Lets see some pics.

Sent from my SGH-I727R using Tapatalk 2

 

[mayday0017]

I think it's for pop off valves, in case there gets to be to much pressure in the head the pop off... pretty much all compressors have them in the heads...

 

[sberry]

Place to put gage?

 

[thinmac]

The part number is 2z499c. Someone sold one on the classifieds a while back: http://www.garagejournal.com/forum/showthread.php?t=140188 It's from a single stage compressor. All four ports are coming out of the head. On each cylinder the air seems to come out of both ports - to get pressure out of the main port I have to cover up the smaller one. The unloader thing seems possible, although it's hard to say since I only have the pump.

 

[lilredex]

This might help, ignore the dust, I didn't prepare it for pictures...... my 499. I used only one of the outputs and left the balance blocked off. I also made an "intake manifold" so I could easily use that inlet filter. The unloader, I believe, is that brass guy mounted on the elbow to the right of the safety pop valve. Something goes "Pssssstcha" when it shuts off, I'll check it next time to see if it is dumping the air.

It has been chugging along like this for about thirty years without problems, so you tend to forget about those components.

 

[TwoInch]

lilred, thats a two cylinder pump right? are you only getting output from one cylinder with that set up?

 

[littletoes]

Eighth inch ports in the heads are for plumbing for a head unloader for starting. Your compressor may have an unloader plumbed in somewhere else, above the tank check valve.

Charles

What Charles said....

 

[lilredex]

lilred, thats a two cylinder pump right? are you only getting output from one cylinder with that set up?

I'd say it delivers out of one or both (inter connected, internally, as Thinmac says above). When you really load it, it recovers just too fast for it to be a single cylinder doing all that work. Keep in mind that set up was done thirty years ago, but.........I can almost guarantee I checked that possibility out.

I may just remove that plug to confirm it.

 

[CalsXS2]

That 1/8" line is most likely the unloader. When the electric motor shuts off, the unloader release's the pressure off of the pump. Other wise your motor would have a hard time starting with a load against the pump.

I hope that makes sense,,, lol.