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.

The most sold KRAL pump

Universal use up to 16 bar.
K series pumps are universal screw pumps, making them the most sold KRAL pump. The pump has a housing made from nodular cast iron. They are approved for use on board ships. In addition, they are equipped with sealed external bearings that are pre-lubricated for their lifetime so they are not stressed by the material being pumped and require no maintenance.


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.
  • 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.

How the K series screw pump fits into the KRAL product program.

The screw pump is available with DIN flanges in an inline configuration, and the KFT series screw pump is available with DIN flanges at the top. Various installation methods are possible for flange-mounting, pedestal and base screw pumps.


Advantages of three screw pumps.

Compared to other types of pumps, KRAL screw pumps offer high capacity without taking up much space. This applies in particular at high differential pressure. The screw pumps are self-priming, with low pulsation delivery and can be easily regulated. The single screw  pumps, single stations and double stations are extremely compact. All K series screw pumps have an internal safety valve.


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
  • Low maintenance operation
  • DIN standard.
  • Technical data
    Technical data15-4255-118160-275370-450550-660851-13011500-17002200-2900
    Qth (1450 min-1, 0 bar)l/min15-4255-118160-275370-450550-660851-13011500-17002200-2900
    Max. pressure at pressure flangebar        
    K 1616161616161616
    KFT 161616     
    with NBR rotary lip seal 9090909090909090
    with FKM rotary lip seal 150150150150150150150150
    with mechanical seal standard 150150150150150150150150
    with mechanical seal hard material 180180180180180180180180
    with magnetic coupling 300300300300300300300300
    max. 10,00010,00010,00010,00010,00010,00010,00010,000
    Max. pressure at suction flangebar        
    with rotary lip seal
    with mechanical seal standard 66666666
    with mechanical seal hard material 1010101010101010
    with magnetic coupling 1010101010101010
  • Models
    KF flange screw pump

    Universal pump for horizontal installation, other mounting positions 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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