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RANGER1
11-08-2013, 08:50 PM
What do you think?

A Mycom screw on NH3 -10sst +35 sct control system failure allowing it to run for 3 hrs with no oil pump.
Safeties would not shut system down due to faulty control relay.
Machine free to turn over & seems to run OK.

HVACRsaurus
11-08-2013, 11:31 PM
How about this one.

Guy on site wasn't wearing his glasses, pushed a bunch of buttons on the VSD to get the thing running, he succeeded - Manual ON but without condenser fans (thermosyphon oil cooling)...

Ran all weekend, discharge temperature went off the dial at over +150C & oil turned black.

When the guys inspected the screw (Mycom 250) they needn't have bothered, it was fine inside.

Forgot to say, no oil pump either..

RANGER1
12-08-2013, 09:01 PM
How about this one.

Guy on site wasn't wearing his glasses, pushed a bunch of buttons on the VSD to get the thing running, he succeeded - Manual ON but without condenser fans (thermosyphon oil cooling)...

Ran all weekend, discharge temperature went off the dial at over +150C & oil turned black.

When the guys inspected the screw (Mycom 250) they needn't have bothered, it was fine inside.

Forgot to say, no oil pump either..

Mycom's can be destroyed, but you really have to try, apparently!

CanadianIce
15-08-2013, 12:17 PM
I spoke to Jerry at Mycom in Selma, Texas. He purposely tried to destroy one for R&D purposes. The machine finally packed it in at 7 psi oil pressure but what he found was, he had to throttle the oil valves to accomplish this. The differential pressure across the package provided enough oil pressure to keep the compressor running.

This test was performed when they were designing the new screw packages with pre lube or no oil pump at all.

Josip
15-08-2013, 01:09 PM
Hi, RANGER1 :)


What do you think?

A Mycom screw on NH3 -10sst +35 sct control system failure allowing it to run for 3 hrs with no oil pump.
Safeties would not shut system down due to faulty control relay.
Machine free to turn over & seems to run OK.

It is possible ... in case of slide bearings there were some oil due to oil DP otherwise I doubt ... with roller bearings even with small oil wouldn't be a problem ...

In the early days of STAL series 80 ... they run compressor for 1/2 hour without oil for test purpose and found out no problems ... info from the test person

Industrial compressors are very rigid machines, but for sure they need lubrication ... and as always there are some extremes ;), but better to not investigate how far we can go ...

Best regards, Josip :)

RANGER1
15-08-2013, 09:35 PM
Thanks for replies, interesting to know what you can get away with to a certain degree.
Discharge temp transmitter only goes to 100 C but went over that, to what temp do not know?
Still running OK after fault rectified.