Page 9 of catalogue Speeding Up Diaphragm Compressors of Andreas Hofer Hochdrucktechnik GmbH

Hochdrucktechnik GmbH

Speeding up Diaphragm compressors

45478 Mülheim-Germany

2

Possibilities to increase the delivery capacity of diaphragm Compressors

At first sight, it may seem simple to increase the delivery capacity of a diaphragm compressor: after all, it just needs more volume per stroke or more strokes per unit of time. However, physics places restrictions on such increase.

2.1 Increasing the displacement per stroke

An increase in the displacement per stroke can be achieved by increasing the diaphragm deflection or increasing the diaphragm diameter. The diaphragm deflection is ruled by specific curve geometries as these determine the life span of the diaphragms as well as the maximum deflection. Since these are decisive factors for the reliability of the compressor no one will change a tried and tested geometry without getting a great improvement. In contrast to this, increasing the diaphragm diameter is the easier method that allows to standardize the product range and to offer different delivery capacity levels. Furthermore, the volume per stroke is proportionate to the cube of the diameter (D3) and has therefore the biggest effect. Changes to the diaphragm head geometry and to the piston dimensions in the Hydraulic drive section can be obtained at relatively low engineering cost. The maximum diameter is determined by the sheet metal sizes available on the market (presently 1400mm). Above a certain dimension there are obvious disadvantages. The sandwich diaphragm will gradually become "softer" as the diameter increases. This effect can be counteacted by increasing the number of individual diaphragms that work together in a "sandwich" set. Of course the manufacturing costs will increase considerably as the material to be cut away multiplies when producing a big diaphragm head. And also e xchanging the diaphragm increase the cost, not least because the significantly increased number of Bolts will lengthen the time needed for the assembly of the diaphragm head.

Page 9