| <BR> | Several allowances must be taken into account to bring the total consumption figure for individual devices to the actual output requirement of a compressor:
Losses v [%]
Losses v through leakage and friction occur in all parts of a pneumatic system. New systems require an allowance of approx. 5% of total FAD to be added for losses. Since leakages and friction losses generally increase when the equipment gets older, losses of up to 25 % should be assumed for older systems.
Reserves r [%]
A pneumatic system is sized according to a current estimate of compressed air consumption. Experience shows that consumption usually rises later. It is advisable to take short and medium-term extensions of the network into account when planning the size of the compressor and main pipelines. If this is not done, later extension of the system can be unnecessarily expensive. An allowance for reserves r of up to 100 % can be taken, depending on the outlook.
Margin for error f [%]
Despite the care taken in calculation, the figures for expected compressed air consumption are still usually wrong. An exact figure can seldom be arrived at because of marginal conditions that are mostly unclear. If a pneumatic system is designed too small and needs to be extended later it will cause additional costs (equipment out of action ), and so an allowance f of 5 - 15 % is advisable to provide a margin for error. |