 Diaphragm Compressors
Constructional features
Multi-stage Diaphragm Compressors
Hofer diaphragm compressors are generally provided
with all necessary fittings, as pressure gauges, oil overflow valves and
compensation pump(s) for the hydraulic circulation and completely fitted
with tubes.
In their standard design they have a V?belt drive with electric motor. All parts are mounted an a base frame made of steel, so that a relief concrete foundation is not required. The new compressor generation is equipped with crank drives, which do no longer have any free dynamic forces and thus, can be installed foundation-free.
Upon request the compressors can be equipped with a valve and instrument panel, which will be designed either for manual or for fully automatic control.
Design of the machines is done in accordance to latest technical development, considering the harmonized European safety regulations (CE-marking) DIN EN 1012 part 1, DIN EN 292 und DIN EN 60204 part 1.
Diaphragm
The metal diaphragms are fitted to be gastight (leakage rate normally approx.
10-4 mbar I/s, in special cases up to approx. 10-8 mbar I/s) and have an average
life of approx. 4000 hours, when working with clean gases uncontaminated by
foreign particles.
Cooling
Due to the large surface of the diaphragm head a considerable part of the
compression heat is lost by radiation to the atmosphere. Larger machines are
equipped with an additional cooling system for the hydraulic oil. The gas-side
cooling is done by interstage coolers and aftercoolers; if requested, 1-stage
machines can also be supplied without aftercoolers.
Oxygen service
For compression of Oxygen a noninflammabie synthetic oil is used for the
hydraulic circuit, instead of the normally used mineral oil.
Materials
Depending an the requirements, the gascontacted parts are mainly provided in
carbon steel or stainless steel. Special designs in Silverin, Monel, Hastelloy
etc. can be supplied upon request.
Principally the diaphragms are made of CrNi-steel, quality 1.4310; for functional reasons, the suction- and discharge valves are of chrome-steel.
Depending an the operating conditions, the metal sealing rings are provided in copper, brass or stainless steel.
Diaphragm failure detection
For indicating a diaphragm failure, a system of multiple diaphragms is applied; 3 diaphragms are inserted together. The center diaphragm is slotted, thus allowing, that pressure enters the collecting chamber, in case a diaphragm failure happens an either gas side or oil side. If such pressure (either gas or oil) prevails in the collecting chamber, the pressure switch being installed in the flange, is actuated, so that a signal can be given or the drive motor is shut down, thus strictly avoiding any penetration of oil in the gas flow.
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