A few years ago, I suggested perhaps the most courageous thing any of us could do was take on compressor service responsibilities of a friend. That's difficult enough in the world of mechanical repairs. It's almost impossible in the world of troubleshooting and diagnosis of problems. This afternoon I found out why.
Sometime back, a friend purchased a used water well rig, which had a new compressor installed prior to his purchase. The rig was a few years old, so he began to tell me details of why the original compressor was replaced, and most important to me, why he had called me after years of not hearing from him. Case in point: after a couple hours of water well drilling, the rig engine would drop a couple hundred rpms, then without notice, the engine would shutdown. As I took down the information, while talking to the customer, my service partner made a quick inspection of the electrical safety shutdown system.
We found the engine oil pressure shutdown switch had vibrated apart and was operating erratically. A replacement switch was necessary, so we connected the switch wires together and eliminated the shutdown problem. It's rare that I have found too many switches, of this vintage, damaged from vibration, so I continued to investigate for any internal compressor or engine problems by installing some test gauges and temperature indicators. At this time we also installed a test orifice to check the output of the air end.
We started rig and it warmed up - we ran the compressor loaded at 350 psig for a few hours - during this test run we observed all test gauges and temperature indicators. We noticed the compressor's interstage pressure was operating about 25 psi higher than normal, as well as a small variation in engine speed of 10 to 20 rpms. We shut the unit down and removed the compressor's oil filter elements. We found at least half a coffee cup of metal and foreign particles at the bottom of the filter canister. We cut both filter elements apart and found both had large amounts of metal, brass, and dirt in them. Since the filters were this contaminated, this would have allowed the compressor filter system to operate in a by-pass mode.
The customer looked at me and said, "What should we do?" The answer was simple enough - clean and inspect the complete compressor system, and all compressor valving and controls. The cooler should be cleaned as well, even though it was recently replaced. I guess there is a kind of perverted logic that might imply operating the compressor until it completely melts down, but I don't think so. Customer gave us the "OK" to remove, clean, and disassemble the compressor system for inspection and repair.
Stress is contagious and I could see my friend was beginning to catch it. I stared at him in utter disbelief and then patiently started to explain that I didn't think all this metal we found could come from a compressor that seemed to be operating, as this compressor was, with just higher than normal interstage pressure. But as we all know, a high interstage pressure means we have excessive wear in the second stage of the compressor, probably due to foreign matter passing through the stage during operation. Unfortunately things had happened in the past that we didn't understand, so even Job would have buckled under the weight of some of these problems.
The compressor and receiver tank were removed from the rig, as well as all component valving and elements and transported to the shop for inspection, disassembly, and repair. Upon disassembly of the high pressure stage, there was evidence of male rotor rubbing and scoring of the discharge flange area, which accounts for the engine speed vibration the customer had reported. Both rotors were marked from foreign matter passing through the stage during operation. The high pressure case also had evidence from foreign matter passing through. Repair parts were ordered and both stages cleaned, machined, and reassembled.
In the end, our customer decided he had some kind of problem with his rig and wanted it taken care of before the summer drilling season came about. How seriously are you supposed to search for a problem? How much time should you dedicate? How many minutes, or hours, do you spend looking? As many as the customer is willing to pay for! That should be the correct answer, but what do you do when the customer doesn't want to invest in the diagnosis or repair? It's a matter of mixed messages - "I have a problem with my rig and I want it fixed....that is until I find out how much it's going to cost." Then you hear - "I didn't think it would cost that much. Can't you do it cheaper?"
This business is tough enough without the added stress of friends who aren't quite sure what they want or if they can have it done cheaper. But remember, everything has a cost - you can't buy a limousine for the price of a small car. We are the professionals in this relationship and it is up to us to manage our interaction with our friends carefully. We stand behind our work - consequently, communications must be crystal clear. Nothing less will do. There can be no room for misunderstanding, no room for miscommunication or ambiguity, and certainly, no room for poor workmanship - at least not from my side of the compressor.
