Page 19 of catalogue Diaphragm Compressors of Andreas Hofer Hochdrucktechnik GmbH

Hofer Diaphragm compressors

page 19 of 20

Fig. 20: simple P&ID 5.2 Drive mechanism Larger-sized diaphragm Compressors are nearly always motor-driven by asynchronous motor via V-belt transmission. The drive pulley on the crankshaft of the compressor is designed as flywheel. Smaller-sized compressors can also be directly coupled to the motor shaft. 5.3 Capacity regulation According to the specified theoretical data, the compressor capacity can be regulated either manually or automatically via a speed-variable drive or via a bypass system. Single-stage diaphragm compressors can also be regulated in capacity by adding the clearance volume. The classic type of regulation, i.e. via valve lifts, is not applicable for diaphragm compressors.

6. Operational safety
Diaphragm compressors, same as any other machine or instrument, have to be carefully incorporated into the safety philosophy of the complete unit. The basic safety requirements are specified in the European directive for machinery 98/37/EC (which has force of law in EC countries). A compressor, built ready for operation, gets the CE-mark, and the compliance of its design and construction with the directive for machinery is attested in a certificate of conformity. If only a ,,bare" compressor without accessories and control unit is supplied, it is accompanied by a manufacturers certificate of the delivered scope. In any case, the operator of the plant or his authorised representative is obliged to carry out a HAZOP-analysis. Such analysis has to specify all hazards, which may originate from the compressor, e.g. due to failures at the compressor itself, failures at upstream and downstream components, or due to mishandling. Hazardous operations have to be avoided by taking suitable preventive measures.