HeatingHeatingElectrical or medium heating for the preheating of highly viscous fluids.
Expansion valveExpansion valveTo prevent an unacceptably high internal pressure within unused parts of the block due to heating and thermal expansion, the switch valve cylinder has two small expansion valves.
Different fluidsDifferent fluidsA two-way valve can be switched manually, electrically or pneumatically, allowing for switching between two types of fuel.
Pump variationsPump variationsDouble stations can be set up with KRAL pumps for pressures up to 40 bar.

KRAL Pump Stations DKC / DLC / DS/L.

Two pumps provide more than double the advantages.

Cost-effective solution for double the flow rate and for maximum operational reliability.
There are critical applications in which a second screw pump is prescribed for security. With KRAL pump stations you have a cost-effective and space-saving solution with which you can prevent motor standstill, production interruptions and heating failures. Maintenance work can also be carried out during operation without pump standstill.

A further advantage of KRAL double stations is the possibility of parallel operation of the two 3-screw pumps. This means that the flow rate can be doubled, but the space requirement and effort are considerably less than with the installation of two single positive displacement pumps.

Typical applications are booster modules of oceangoing ships, and burner stations in marine and industrial applications. Maximum reliability is required. The most common operating mode is therefore that one screw pump is running and the other is switched off (standby).

Operation, materials, components.

  • Delivery rate: 5 to 280 l/min.
  • Max. differential pressure: 40 bar.
  • Temperature range: -20 °C to 180 °C.
  • Housing: Nodular cast iron EN-GJS-400.
  • Triple 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, media or steam.
  • Seal type: Mechanical seal standard or hard material.
  • Available with magnetic coupling.

In the case of a ship, the failure of the fuel screw pump in the booster module means that the engine comes to a standstill. If the flame goes out in a burner, a production process will be interrupted or a heating system will fail. Such applications require security. For maintenance, the primary screw pump can be switched to the standby screw pump, without interruption.

Cost reduction through many functions in compact space.

If a second screw pump is necessary, it soon becomes clear that the cost of design, pipework and control is considerable. The space requirement for a structure involving individual components is also very large. A significantly more economical solution is represented by the completely newly developed DKC and DLC dual stations by KRAL. Two screw pumps of the K series up to 16 bar or L series up to 63 bar are fitted to one block. The block integrates all functions within minimum space, and is available with many further options. And the flow rate can be doubled.

Alternate operation between two liquids.

For alternate operation between light and heavy oil operation, for example, the operator does not have to carry out any complex pipework when using KRAL pump stations. As an option, a liquid changeover switch can be fitted. In this way, KRAL dual stations are connected to two pipeline systems with different liquids. Switching between the liquids is manual, electrical or pneumatic. For remote monitoring of the lever position, limit switches are available.

Service without stopping the screw pump.

Reliability through a standby screw pump which is always available is the basic idea of the dual station. In this way, maximum reliability is ensured. After the changeover, the switched-off port of the station block is depressurized and the screw pump can easily be removed. The ship’s engine continues to run, the production process is not interrupted, the heating system continues to operate.

Extremely easy installation.

KRAL dual stations with two 3-screw pumps are quickly set up and fixed. In the simplest case, the suction and pressure lines have to be connected. Done! The connections for the suction and pressure sides are at the front, so they are easy to reach. In contrast to the traditional structure involving two individual screw pumps, apart from connecting the suction and pressure lines no development, design or pipework is required. That saves a lot of time and money.

Various applications.

KRAL double stations with two 3-screw pumps are an economical and reliable solution for all industries in which a continuous supply of oil is required: in oil firing technology for delivering heating oil, circular pipeline transfer screw pumps and burner screw pumps for industrial furnaces, in public buildings and in the ship building industry.

Many useful options are available.

  • Heating variants for heating highly viscous fluids.
  • Two-way valve for switching between liquids.
  • Pressure-retaining valve for constant feed pressure.
  • Pressure switch for monitoring pressure.
  • Differential pressure display for monitoring the loading of the strainer.
  • Temperature measurement of the fluid.
  • Monitoring leaked oil.
  • Strainer cover protection to prevent accidents caused by oil being sprayed out.

Accessory: KRAL precision flowmeters.

Maintenance work without downtime.

KRAL block aggregates stand out for their ready-for-connection, compact construction. Both of the installed KRAL screw pumps are self-priming pumps with low pulsation and operate at a low noise level. Switching over from the operating screw pump to the reserve screw pump can be carried out electrically or manually. Screw pump maintenance and filter cleaning can be performed without interrupting operations.

Your advantages.

  • Reliable solution for many applications.
  • High operational reliability.
  • Liquid switching without complex piping.
  • Doubling of the flow rate.
  • Lower costs for design, piping and control.
  • Simple installation.
  • Service without pump standstill in the system.
  • For different pressure ranges, as required.
  • Technical data.

    DKC series.

    Technical data5-4255-118
    Qth (1450 min-1, 0 bar)l/min5-4359-119
    Max. pressure at pressure flangebar  
    K 1616
    KFT 16 
    with NBR rotary lip seal 8080
    with FKM rotary lip seal 150150
    with mechanical seal standard 150150
    with mechanical seal hard material 180180
    with magnetic coupling standard 180180
    with magnetic coupling high temperature 250250
    min. 22
    max. 10,00010,000
    Max. pressure at suction flangebar  
    with rotary lip seal 66
    with mechanical seal standard 66
    with mechanical seal hard material 66
    with magnetic coupling 1616

    DLC series.

    Technical data5-1015-2632-5455-85
    Qth (1450 min-1, 0 bar)l/min5-1015-2632-5858-84
    Max. pressure at pressure flangebar40404040
    Temperature max. pumped liquid°C    
    with radial shaft seal NBR 80808080
    with radial shaft seal FKM 150150150150
    with mechanical seal standard 150150150150
    with mechanical seal hard material 180180180180
    with magnetic coupling *     
    max. 7,0007,0007,0007,000
    Max. pressure at suction flangebar    
    with radial sealing ring 6666
    with mechanical seal standard 6666
    with mechanical seal hard material 6666
    with balanced mechanical seal     
    model LFI/LFT/LFW/LVI/LVT 20202020
    model LFM  6666
    with magnetic coupling *     
    * customer-specific, contact KRAL     

    DS/L series.

    Technical data5-1015-2632-54
    Qth (1450 min-1, 0 bar)l/min5-1015-2632-57
    Max. pressure at pressure flangebar666
    Temperature max. pumped liquid°C   
    with radial shaft seal NBR 808080
    with radial shaft seal FKM 150150150
    with mechanical seal standard 150150150
    with mechanical seal hard material 180180180
    max. 7,0007,0007,000
    Max. pressure at suction flangebar   
    with radial sealing ring
    with mechanical seal standard 666
    with mechanical seal hard material 666
  • Models.
    Double stations DKC and DLC.

    The compact double stations DKC and DLC consists of two KRAL screw pumps K or L series, station block, hoisting eye, suction-side pressure gauge, strainer cover, pressure-side pressure gauge, reversing valve lever, vent valve, pressure connection and suction connection. More options on request.

    Double stations DS1, DS3, DS4, DL3, DL4.

    The double stations DS1, DS3, DS4, DL3, DL4 consists of two KRAL NE screw pumps , two strainers, two non-return valves, overflow valve, two lockable vacuum gauges, lockable pressure gauge, oilpan and one lever control with counter flanges. More options on request.

    Double station DL2.

    The low pressure double station DL2 consists of two KRAL FE screw pumps, two strainers, two non-return valves, overflow valve, lockable pressure gauge, oilpan and lever control with counter flanges. More options on request.

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  • Operating instructions.
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