Compressor is a NH3 Frick RWBII 76H, Variable VI, nineteen years old. Total hours are unclear, but most likely 75,000 Plus.
150 HP, Liquid Injection Oil Cooling. Economizer is feed from a TX Valve (currently off).
The original installation has been modified to work on Blast Freezers in nearby Building. It originally was connected to a Spiral Freezer. The Spiral Freeze is no longer in use. The Suction was piped to the nearby building and the HP Receiver is piped to an LPR in the next building. System seems to work OK from the standpoint of two systems hooked together. There is a total of 500HP in the next building connected to the same suction line which runs @ 14” HG or so
I installed a New Frick Panel five years ago on this machine. The old one was becoming erratic. The Install went smoothly. At the time I recall a bit of trouble doing the Slide Valve Calibration, but nothing of major importance. One of my co-workers work on this machine years before that and seems to recall a great deal of wear in the slide valve.
The Customer reported a lack of ability to get any work from the machine.
In the past year and one half the Maintenance people have replaced the Suction Check Valve (it stuck closed) , as well as both the Capacity and Slide Stop Solenoid Valves. In addition the Program Chips have been replaced as well as the Liquid Injection Solenoid Valve that diverts liquid to one of two ports depending on the VI. The customer is competent and has a Serviceperson of their own that travels to their different plants.
The operator demonstrated that at 100% Slide Valve and 5.0 VI the Amperage Draw was 50%. As he dropped the VI in Manual Mode the Amp draw increased, as was to be expected.
Starting with basics I calibrated the Slide Stop and Slide Valve. SV Pot rotation (In 5.0 170 Degrees, and 2.2 300 Degrees). VI Pot travel was normal. I also checked the CT Factor and Measured the Amp Draw to confirm .
Starting up I noticed these conditions.
(100% SV, 5.0 VI) 3.0 LBS Suction-150LB Discharge-Motor Current-50%-Suction Temp +70F, Suction Check banging
Changing the VI to 4.4 yielded this.
(100% SV, 4.4 VI) 6”HG Suction-150LB Discharge-Motor Current-70%-Suction Temp -5F, Suction Check clicking
Changing the VI to 2.2 yielded this.
(100% SV, 2.2 VI) 12.5HG Suction-150LB Discharge-Motor Current-95%-Suction Temp -40F
It was apparent that the lower I took the VI the more gas was being pumped. The lack of sound from the Suction Check and drop in Suction Temp confirmed that.
Calibration is not an issue. I worked the SV and Vi Solenoid Valves manually and got the same results. Everything moves in the proper direction at the proper time.
I contacted Frick. They are a very competent bunch and very helpful. (I commend them.)
However they were unable to suggest a fault (Internal or External) that could cause this.
According to their figures, at 2.2 VI it should be drawing 200 HP.
My only option at this point is an internal inspection.
Has anyone else every seen anything like this?