Removing Oil From a Semi-Hermetic Compressor

April 3, 2006
/ Print / Reprints /
ShareMore
/ Text Size+
Occasionally a technician may need to temporarily add oil to a semi-hermetic reciprocating compressor to maintain an adequate oil level, if the oil has been trapped out in the evaporator or suction line. This additional oil should not be left in the system.

The cause of the oil trapping should be identified and repaired in a timely fashion. If the additional oil returns to the compressor, it could cause damage as a result of oil slugging or excessive oil pumping.

OIL DRAIN PLUG OPTION

There are several methods for removing oil from a semi-hermetic reciprocating compressor. The easiest is through an oil drain plug. If the compressor is equipped with an oil drain plug, all a technician must do is reduce the pressure in the crankcase by running the compressor and front seating its suction service valve.

1. Pump the system down to 1 to 2 psig.

2. Shut down the compressor.

3. Once the compressor is off, front seat its discharge service valve, which will completely isolate the compressor from the system.

4. Carefully loosen the oil drain plug and allow the oil to seep out of the compressor around the thread of the plug until enough oil has been removed. Note: Do not totally remove the plug from the compressor. Only allow the oil to seep around its threads.

WITHOUT AN OIL DRAIN PLUG

If the compressor is not equipped with an oil drain plug, or if it is not convenient to use, oil can be removed from its oil fill plug.

Use the following procedure:

1. Attach a gauge manifold to the access ports of the suction and discharge service valves.

2. Front seat the suction service valve and run the compressor.

3. Continue running the compressor until the crankcase pressure has reached 0 psig.

4. Shut down the compressor.

5. Front seat its discharge service valve.

6. Remove the oil fill plug from the compressor.

7. Insert a 1/4-inch O.D. copper tube with a shutoff valve into the oil fill plug opening. Position the 1/4-inch copper tube so that one end is near the bottom of the crankcase and the other end, which is external to the compressor, is positioned below the oil level of the compressor and into an approved container.

8. Place a rag around the 1/4-inch O.D. copper tube where it exits the compressor.

9. Using dry nitrogen, pressurize the compressor crankcase through the suction service valve's access port to about 5 psig.

10. The oil should drain from the compressor. If necessary, repressurize the crankcase with dry nitrogen.

11. Once a sufficient amount of oil has been removed, remove the 1/4-inch O.D. copper tube.

12. Reinstall the fill plug.

13. Evacuate the system to 500 microns.

14. Backseat both the suction and discharge service valves.

15. Restore power to the compressor and place it back in operation.

This method is more time consuming, but it will allow oil to be removed from a compressor. Before using this procedure, make sure the compressor does not have an oil drain plug. Removing oil from a compressor using its oil drain plug is normally a much easier process.

Joe Marchese is owner of Coldtronics of Pittsburgh. He can be reached at 412-734-4433, www.coldtronics.com, or joe@coldtronics.com.

Publication date: 04/03/2006

Did you enjoy this article? Click here to subscribe to The NEWS Magazine

You must login or register in order to post a comment.

Donald Budzynski
May 2, 2012
Instead of using a rag to seal the hole. Take a 1/4" mip x 1/4 compression fitting and drill out the stop from the pipe threaded end. Use a plastic ferrule or 2, 1/4 orings to seal the tubing. This will allow you to set the depth and lock the tubing in place, thus freeing up your hand.

Multimedia

Videos

Image Galleries

2014 MCAA Annual Convention

Scenes from the 2014 MCAA Annual Convention in Scottsdale, Ariz.

Podcasts

NEWSmakers: Julian Scadden

Training is an ongoing process. Julian will discuss how you can generate maximum return on time and energy invested training by following a three part process. Listen to this podcast to get expert tips on training, tracking and follow up. 

More Podcasts

THE MAGAZINE

ACHRNEWS

NEWS 04-21-14 cover

2014 April 21

Check out the weekly edition of The NEWS today!

Table Of Contents Subscribe

SERVICE CALLS POLL

Which statement on service calls best applies to your business?
View Results Poll Archive

HVACR INDUSTRY STORE

plumbing-hvac.gif
2014 National Plumbing & HVAC Estimator

Every plumbing and HVAC estimator can use the cost estimates in this practical manual!

More Products

Clear Seas Research

 

Clear Seas ResearchWith access to over one million professionals and more than 60 industry-specific publications, Clear Seas Research offers relevant insights from those who know your industry best. Let us customize a market research solution that exceeds your marketing goals.

DON'T MISS A THING

Magazine image
 
Register today for complete access to ACHRNews.com. Get full access to the latest features, Extra Edition, and more.

STAY CONNECTED

facebook icontwitter iconyoutube iconLinkedIn i con