piston air compressor

All piston air compressor with the exception of a few dry crankcase air compressors use oil.

The oil provides lubrication for the rod bearings, piston pins, main bearings and cylinder walls (lubricated compression machines). The oil should provide for rust prevention because water can condense in the crankcase of a compressor when it has stopped running and cools down.

There are two general type of compressors that do not have oil in compression cycle. One type does not have any oil in the crankcase and uses a combination of special materials to reduce friction and wear on rod bearings, piston pins, main bearings,and cylinder walls. The other type use a crosshead design that does not permit oil to enter the compressions chamber(s). The oils in these crankcases are not stressed and generally formulated much like hydraulic oils but higher higher viscosity generally around 100 SSU @ 1000 F. (30 Wt) for room temperature operating conditions. Follow the manufactures recommendation as the fit and finish of parts affect the viscosity of the oil.

By far the most common piston compressor is the lubricated single acting air compressor. Oil is present in the crankcase lubricating the crank and rod assemblies. A small amount of the oil passes in to the compression chamber lubricating and assists in sealing of rings and valves. However in heavy load conditions temperatures can become high enough to break down this oil into hydrocarbons that are sticky by nature. Under these conditions valves become coated with this sticky material and catch and hold contaminates that pass through the inlet filters as well as wear materials. This forms a very hard deposit that will cause the valves to stop working properly. Under extreme conditions (compressor loaded more than 80% time) can result in the need to do a valve job in a year or less.

Under these severe load conditions we recommend the use of a diester synthetic such as our PP-7 5 gallon pail for $249.00. These oils resist the formation of the breakdown products plus it removes these deposits. We do not recommended using this product to clean up a compressor as some of the larger deposits may break loose and plug air passages resulting in damage to the compressor and possibly causing a fire from the plugged passage.

Even for compressors under lower loads will result in power saving as valves that leak wastes energy. The use of PP-7 reduces this leakage and will provide for energy savings.

Tags: piston ari compressor