It is more effective and efficient to make use a single Copeland compressor. Two or more compressors are only used in cases where using only one is inevitable. In such a situation, piping and sizing should be done carefully. One of the best ways of arrangement is whereby, at the oil level, the equalizer connects to the crankcase. This arrangement ensures that machines are at the same level. In a scenario where the machines are of different sizes, the height of the bases should be set in such a way that level of regular oil quantity is on the same elevation. If the height of the bases is not adjusted, the oil flows and collects to the machine on the lower level. This kind of arrangement is referred to as the single-pipe crankcase equalizer. Note that the method is only effective in a setting where the machines have one equalizer tapping going into the crankcase at such an angle that the base of the tapping slightly touches the oil level of normality.
The other method of the arrangement ensures the proper oil level is maintained by making use of two lines of equalizers between the crankcase. One equalizer line goes up above the average level of oil while the other line goes below it. The upper line is composed of a gas line that has the primary function of averting any difference in crankcase pressure. A difference in pressure would compel the flow of oil into the lower equalizer line. Pockets that prevent the proper movement of oil should also be eliminated. The crankcase equalizer is also composed of valves that have their stems set into a horizontal position. This ensures that the correct oil levels are maintained; no oil can rise above the valve seat.
It should also be ensured that all discharge pipes coming from the compressors are equalized prior to entering the condensers. The overall effect of this is that all condensers now act as a single condenser. At this point, levels of pressure should be maintained carefully because a pressure drop in the equalizer line may drain one condenser of all the liquid as it flows to another condenser.
U-traps or oil separators serve the main purpose of ensuring that the oil does not flow back into the compressor head when the system is switched off. Little amounts of the refrigerant gas are pumped through the system when a compressor contents are unloaded. The speed at which these gas moves should be kept in check up to an absolute minimum to ensure that the oil keeps on moving within the system. The situation proves to be problematic however in cases where the flow of gas is in an upward direction. However, the designer can implement the use of a double riser to overcome this problem. The double riser has a small line that is created to ensure low speeds, whereas another larger line ensures that speeds in the two lines are almost the same as the speed of the horizontal flow.
In cases where an oil separator is used at the base of the discharge gas riser, the use of a double riser is not necessary. NOTE that, there should be a water-regulating valve for a system using many condensers; this ensures that every condenser gets an equal quantity of the condenser water.