KRAL – DKC / DLC / DS/L twin pump station
The KRAL twin pump station is two three-screw pumps mounted in a single cast block: one runs while the second stands by and is brought into service by moving a lever. The manufacturer KRAL (Austria) produces three series of such stations — DKC, DLC and DS/L. Compared with installing two separate pumps each with its own pipework, the block solution saves up to 50% of floor space and removes most of the piping, flanges and supports.
What a KRAL twin pump station is and why a second pump is needed
In heavy fuel oil systems, on burners and in marine fuel systems, a loss of supply means shutting down the entire boiler or engine. The second pump in the block removes this dependency: switching to standby is done manually by a lever, without dismantling and without a lengthy line stop. Both pumps can also run in parallel when double capacity is required.
The KRAL twin pump station is supplied as a ready-made assembly: block, two suction filters, check valves, pressure gauges, air vent valve and lifting eye are already in place.
Three series: DKC, DLC, DS/L
| The series | Pumps | Pressure at the discharge flange | Viscosity | Typical application |
|---|---|---|---|---|
| DKC | KRAL K | up to 16 bar | 2–10,000 mm²/s | Heavy fuel oils, the widest viscosity range |
| DLC | KRAL L | up to 40 bar | 1.5–7000 mm²/s | Burners, fuel conditioning |
| DS/L | — | up to 6 bar | 1.1–7000 mm²/s | Transfer and circulation without high back pressure |
KRAL twin pump station: technical specifications
| Parameter | Value |
|---|---|
| Capacity | 5–280 l/min (across the series) |
| Capacity by series (per pump) | DKC 5–119 · DLC 5–84 · DS/L 5–57 l/min at 1450 rpm, 0 bar |
| Medium temperature | −20…+180 °C |
| — NBR lip seal | 80 °C |
| — FKM lip seal / standard mechanical seal | 150 °C |
| — mechanical seal in hard materials | 180 °C |
| — high-temp magnetic coupling (DKC) | 250 °C |
| Inlet pressure | 6 bar · up to 16 bar with magnetic coupling · up to 20 bar with balanced mechanical seal (DLC) |
| Body | High-strength cast iron EN-GJS-400 |
| Screws | Nitrided steel |
Scope of supply and options
Block heating for handling viscous media. Two-way valve for switching between two liquids. Back-pressure valves. Pressure switch, filter differential pressure indication, temperature measurement, leakage monitoring. Magnetic coupling instead of a mechanical seal where leakage is unacceptable.
Classification approvals: ABS, BV, CCS, DNV, GL, LRS, MRS, NK, RINA. ATEX II 2 GD b/c version.
Where KRAL pump stations are used
Heavy fuel oil systems of boiler houses and supply to burners. Marine fuel systems and marine steam generator boilers — KRAL cites the example of a DLC station on heavy and light fuel oil with a pressure of 40 bar and a capacity of 240–9000 l/h. Circulation circuits for process liquids. Supply of lubricants and hydraulic oils wherever a standby unit is required.
About the pumps the stations are built from: KRAL — L Series three-screw pump and KRAL — K Series three-screw pump. Operating principle — in the article Features of screw pumps.
Selection and service from Steiner Ukraine
A station is selected by viscosity at operating temperature, the required pressure, NPSH margin and start-up conditions on cold medium. We calculate the duty point for your existing scheme, agree the series, seal type and list of options, and supply the station complete with motors. Then come commissioning, spare parts and service. Steiner Ukraine has been on the industrial equipment market since 2006.
