Sundyne LMC 337 Problem

[hamedfazel123]

Hello
During over hall; before installing Sundyne LMC 337 compressor we decided to test it in free-Load mode without fluid. Both suction and discharge was open.
First we tested gearbox without impeller and oil pressure (in 50 degree centigrade) was 2.2 barg. Vibration in all parts of gearbox was less than 1 Rms.
But after installing impeller and cover impeller and nut, high vibration in compressor casing and high speed shaft appeared (about 10 Rms) and high speed shaft touched with lower journal and impeller blades contacted with diffuser.
Before that compressor stopped working, vertical vibration in Compressor casing appeared but there was no horizontal vibration.
High speed shaft assembly was balanced.
Now I have 2 question:
1-Why after installing impeller and … high vibration appeared?
2-Is running compressor without load (fluid) for testing is OK?
Thank you

 

[JJPellin]

How do you test a compressor without fluid? Please describe the test.

Johnny Pellin

 

[JJPellin]

As I reread your post, it sounds like you tested the compressor by running it to stonewall with the suction and discharge open to the atmosphere. Correct me if I am wrong.

Our Sundyne compressors are model LMC-333 and operate in hydrogen service. Our motors would overload running wide open on air.

Running off the end of the curve could result in radial bearing overload and failure. These are high speed machines and should only be operated with appropriate back pressure close to rated flow.

Johnny Pellin

 

[hamedfazel123]

thank you very much.