Dry-running with hydraulic drive unit (type TKH)

HOFER Piston Compressors

Hydraulically driven, dry-running HOFER piston compressors of the type TKH, have a particularly simple design. They ensure a lubricant-free compression of non-corrosive gases, such as hydrogen, helium, argon, nitrogen, carbon dioxide and ethylene. The maximum discharge pressure is approx. 60,916 psi (4200 bar). HOFER piston compressors are exceptionally easy to maintain. A piston packing can be replaced in approx. 10 to 30 minutes, depending on the compressor size.

If the compressor is used in a hazardous area, the hydraulic unit is usually installed in a non-hazardous area. The hydraulic unit is connected through a gastight wall.

Explosion proof hydraulic units are available on special request.

The HOFER TKH piston compressor needs only little space. Since the stages can easily be arranged above one another, it is ideally suited for the installation in containers.

Features at a glance

  • discharge pressure up to 60,916 psi (4,200 bar)
  • dry running piston for lubricant-free compression
  • easy and quick maintenance
  • easy flow control by changing the number of strokes from 5 to 100%
  • constant monitoring of leakage rates
  • stage pressure ratios up to 5
  • arbitrary number of stages
  • mass compensation for foundation-free installation
  • wear resistant and smooth operation due to low piston speeds
  • water cooling provides the best cooling effect as well as a low sound pressure level
  • manufactured in compliance with 2006/42/EC EC-Machinery Directive.
    Applied standards: DIN EN 1012 part 1, DIN EN 12100 part 1, DIN EN 60204 part 1 et al.
  • explosion proof according to the European Directive 2014/34/EU, if necessary

More details

Principle of operation

The special construction and design of the piston packing allows to operate completely without the lubrication of these sealing elements at higher discharge pressures, although under normal circumstances lubrication is absolutely required.The gas piston gets the required sealing and sliding properties through the design of the packing structure with the materials specially developed for this purpose. The gas space and the gas to be compressed are kept free from undesirable lubricants.

Hofer piston compressors of the TKH type series are preferably designed in a two-stage, respectively one-stage double-acting design. The unit is driven by oil-hydraulics. The hydraulic cylinder is positioned between the first and second stage. A hydraulic pump with control devices pressurises the hydraulic cylinder alternately with hydraulic oil. Contact-free limit switches activate the stroke reversion.

Mixing of the two media is excluded due to the separation of the hydraulic and the gas chamber and by use of double seals. The force required for gas compression is generated by the oil pressure and the corresponding ratio of piston diameters.

The capacity is regulated by the piston speed (number of strokes) through varying of the flow rate of the pump. The frequency of strokes, and thus the suction capacity of the compressor can be continuously regulated between 0% and 100% via a standard analogue signal. Upon request, instruments for the detection of gas and oil leaks can be integrated. This allows the permanent monitoring of the condition of the gas and oil-side seals.

The gas, which is compressed in the different stages, is cooled by the respective downstream inter-stage and after coolers. Here, the temperature difference is approx. 10 K in relation to the cooling water inlet temperature. Usually, the hydraulic unit is also connected to this cooling circuit.

Compression ratios, pressure levels, performance

The suction capacity of the compressor is determined by the suction pressure, the discharge pressure and the frequency of strokes. The various models are listed in the product brochure on the right hand side (further performance data on request).

The stated driving powers apply to the maximum operating data.

Selection of Diaphragm Compressors

HOFER piston compressors of the type TKH are generally custom-made.
Here are some examples:

Piston compressor TKH, two stages: TKH 52/36 - 200 - 50

Piston compressor TKH two stages:
TKH 52/36 - 200 - 50

Type of gas:

H2, He, Ar, N, CO2, C2H4

Discharge pressure:

7,250 psi (500 bar)

Piston compressor TKH, single stage double acting: TKH 28/28 - 80 - 100

Piston compressor TKH single stage double acting:
TKH 28/28 - 80 - 100

Type of gas:

H2, He, Ar, N, CO2, C2H4

Discharge pressure:

7,250 psi (500 bar)

Piston compressor TKH, four stages: TKH 125/125-500-5 + TKH 84/42-500-50 + TKH 52/52-500-100Piston compressor TKH, four stages: TKH 125/125-500-5 + TKH 84/42-500-50 + TKH 52/52-500-100

Piston compressor TKH four stages:
TKH 125/125-500-5
TKH 84/42-500-50
TKH 52/52-500-100

Type of gas:


Discharge pressure:

13,068 psi (901 bar)

including valve panel ready installed in container