Venting the seal chamber. Venting the seal chamber. The seal chamber has a separate vent hole. This allows the pump to be vented easily and correctly during startup.
Wear reducing surface treatment. Wear reducing surface treatment. A special heat treatment of the pump housing minimizes friction and wear.
Optimal cooling and lubrication. Optimal cooling and lubrication. The application specific design of the balancing cylinder ensures proper cooling and lubrication of the sealing surfaces of the mechanical seals.
Self-purging. Self-purging. Venting between the positive pressure side and negative pressure side directly depends on the mechanical seal. In this way, it´s ensured that the air buffer through the medium in the vent line can be eliminated, even for vertical installation.

KRAL K Series Screw Pumps.

Universally applicable screw pump.

For pumped media up to 16 bar.
One of our best-selling products: compact and universally applicable, reliable and efficient. These are the KRAL screw pumps of the K series. Their housing is made from nodular cast iron and they have a sealed, lifetime-lubricated, service-free external bearing. The KRAL K series screw pumps are approved for use on board ships.


Operation, materials, components.

  • Delivery rate: 5 to 2,900 l/min.
  • Delivery rate KFT: 5 to 510 l/min.
  • Max. differential pressure: 16 bar.
  • Temperature range: -20 °C to 180 °C, magnetic coupling to 300 °C.
  • Viscosity: 10,000 mm²/s.
  • Housing: Nodular cast iron EN-GJS-400.
  • Screws: Steel, nitrided.
  • Approvals: ABS, BV, CCS, DNV, GL, LRS, MRS, NK, RINA.
  • ATEX: II 2 GD b/c group II, category 2.
  • Heating: Electrical, fluid media or steam.

Advantages of the KRAL K series screw pumps.

Suitable for many applications, very compact, robust, flexible, excellent price-performance ratio. Perfectly adequate for pressures up to 16 bar. All products of the K series have an internal safety valve and can be ordered with DIN flanges in inline arrangement (except KFT and KFN). Like all KRAL screw pumps, the pumps of the K series are self-priming, deliver with low-pulsation and, in contrast to other functional principles, can be easily regulated.


Advantages of the KRAL screw pumps.

Compared to other types of pumps, KRAL screw pumps convey a wide variety of media, qualities and viscosities in consistently high quantities, even at high differential pressure. Further advantages are the compact design and the high flexibility.


Stop coupling damage.

With some liquids, residue can build up, which may cause the pump to fail. A typical spot for residue to build up is at the mechanical seal. The residue damages the ball bearing, which runs hot, melts the elastomeric ring and damages the coupling. With the K series screw pump, there is a weep hole next to the mechanical seal, to prevent the fluid from collecting and building up as residue.



KRAL offers the advanced quality of SiC mechanical seals, which contain graphite, as a solid lubricant to reduce the coefficient of friction in dry running conditions. The O rings with high fluorine content are suitable for higher temperatures and are chemically stable. The K series screw pump offers innovative seal concepts. A proven selection of radial rotary shaft seals, mechanical seals and a hermetically sealed magnetic coupling are available as standard. A robust and compact design rounds off the profile.

Your advantages.

  • No coupling damage through well placed leakage hole.
  • Safety reserve in dry running.
  • Viscosity of 10,000 mm²/s.
  • Differential pressure: 16 bar.
  • Low service operation.
  • DIN standard.
  • Technical data.
    Technical data 15-42 55-118 160-275 370-450 550-660 851-1301 1500-1700 2200-2900
    Qth (1450 min-1, 0 bar) l/min 15-42 55-118 160-275 370-450 550-660 851-1301 1500-1700 2200-2900
    Max. pressure at pressure flange bar                
    K   16 16 16 16 16 16 16 16
    KFT   16 16 16          
    Temperature °C                
    with NBR rotary lip seal   90 90 90 90 90 90 90 90
    with FKM rotary lip seal   150 150 150 150 150 150 150 150
    with mechanical seal standard   150 150 150 150 150 150 150 150
    with mechanical seal hard material   180 180 180 180 180 180 180 180
    with magnetic coupling   300 300 300 300 300 300 300 300
    Viscosity mm²/s                
    min.   1.1 1.1 1.1 1.4 1.4 1.4 1.4 1.4
    max.   10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000
    Max. pressure at suction flange bar                
    with rotary lip seal   1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5
    with mechanical seal standard   6 6 6 6 6 6 6 6
    with mechanical seal hard material   10 10 10 10 10 10 10 10
    with magnetic coupling   10 10 10 10 10 10 10 10
  • Models.
    KF flange screw pump.

    Universal pump for horizontal installation, other mounting solutions possible.

    KH foot screw pump.

    Mounted horizontal onto base frames.

    KV pedestal screw pump.

    The right choice if the installation area is narrow or if there is not enough space available.

    KFT screw pump with overhead DIN flanges.

    For horizontal or vertical installation.

  • NPSH.
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  • Operating instructions.
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