|
0 - 2000 hours
$ 520
4 work hours |
|
2000 - 3000 hours
$ 1,000
10 work hours |
|
3200 - 4000 hours
$ 4,800
38 work hours
$ 6,320
52 work hours |
| 0 hours: New Sperre compressor in top condition: We should be able to get by without extra parts on board. The company wants to cut costs.
200 hours: Changes running-in oil. Uses the same oil as for the auxiliary engine. Unnoticed, oil coke starts to build up on the valves and the coolers. Engine oil lacks the antioxidants (anti-coking) added to compressor oil.
1000 hours: Cleans the coke off the valves and puts the old parts back. Does not see that one of the valve gaskets (a copper ring) is slightly damaged. Changes the oil, using auxiliary-engine oil again. The damaged gasket causes a leak in the valve. The valve gets extremely hot, so coke builds up rapidly. A valve plate cracks...
1800 hours: Orders a set of non-genuine valves and valve gaskets from the cheapest supplier. Until they arrive, the compressor is out of service. "Why pay more for a Sperre logo on the box? The supplier says the non-genuine parts are fully compatible, just cheaper." "But without two starting compressors, the ship shouldnLt really be sailing. LetLs hope no inspectors arrive." |
|
2000 hours: Because of the coke build-up, the compressor has to work harder. The non-genuine valves start to leak. The compressor gets even hotter. The higher the temperature, the more oil coke. The piston rings get stuck in the grooves, and air starts escaping past the rings. The com-pressor must work even harder... The low-pressure (LP) valve starts leaking. The heat causes scoring of the piston.
2500 hours: The LP cylinder has to be overhauled. The LP piston and piston rings are damaged and have to be replaced. The cheaper supplier stocks a non-genuine LP valve and piston, but no rings - these are ordered from Sperre.
3000 hours: The non-genuine piston has incorrect tolerances. The compressor starts using much more oil, and the oil content of the compressed air increases dramatically. The valves and coolers get more coked than ever before. |
|
3200 hours: The high-pressure valve is replaced again. The coolers as well as the LP valve have to be cleaned. Oil in the compressed air starts causing problems in filters and other equipment in the compressed-air system. A clamp on a cooler tube has not been properly fastened. It loosens, and the cooler cracks.
3600 hours: The compressed-air system must be cleaned. Some filters and membranes in regulating valves have to be replaced. An extra filter is installed in the compressed-air system to remove all the oil. The low-pressure cooler is replaced with a new one from Sperre. The non-genuine LP valve has now been running for nearly 1500 hours. Springs and plates are of poor quality and have become very worn. A spring breaks and is sucked into the cylinder. The non-genuine piston sticks in the cylinder, and is worn off near the gudgeon pin. Loose parts from the piston and the conrod damage the crankcase, bearings and crankshaft. The compressor breaks down completely. The crew call for help from Sperre.
4000 hours: Sperre's serviceman rebuilds the compressor completely, replacing all the worn and low-quality parts. Now the compressor is as good as new, and with the right care it will provide excellent service for many years to come. |
