KRACHT KF Series Modular Gear Pump

Overview

The KRACHT KF series is a modular range of low-pressure external gear pumps that covers nominal sizes from KF 2.5 up to KF 3150, with geometric displacements from 2.55 cm³ per revolution in the smallest frame to 1,473 cm³ per revolution at KF 1500, and larger sizes available on request. Every size uses helical gearing and works at up to 25 bar, which is why the family is a standard choice for lubricating oil supply, fuel handling and general fluid transfer. This page describes the whole family so engineers can select the right size, seal and valve before narrowing to a single type code.

Seven Star LLC supplies the KRACHT KF series in Oman and across the GCC, with engineering support in Muscat. Because the family offers many seal, valve, flange and drive variants, buyers get the best result by sending us the medium, viscosity, temperature, speed and flow they need, after which we help turn them into a correct KRACHT type key and a formal RFQ. A specific size, the KRACHT KF80RF2-D15 gear pump, is described on its own page.

Operating Principle

A pump from the KRACHT KF series is a positive displacement machine. Two meshing gear shafts rotate inside a close-tolerance housing, and fluid is carried from the suction side to the discharge side in the tooth gaps along the housing wall. The geometric delivery volume is displaced on every revolution, so flow is proportional to speed, and the pump is self-priming, although very high viscosities may require a small pre-pressure. Pressure only builds once external loads such as delivery head, line resistance or fittings are present, which is why the system needs a relief valve.

In the KRACHT KF series, helical tooth geometry combined with a special gear profile gives low noise and low pressure pulsation; the catalog quotes sound pressure levels between 65 and 86 dB(A) at 1 m depending on size and pressure. The pumps should always run in the specified direction of rotation, must not run dry, and need a medium with a minimum lubricity that is chemically compatible with the materials. On the suction side the relative pressure should not drop below −0.4 bar, with −0.6 bar tolerated briefly during a cold start.

Engineering Design of the KRACHT KF series

In the standard build, the housing parts of sizes 2.5 to 1500 are grey cast iron EN-GJL-250, and the housing parts of sizes 1800 to 3150 are spheroidal cast iron EN-GJS-400-15, which is also selectable on smaller sizes. The gear sets are made of high-strength case-hardened steel 1.7139 and run in special multi-layer plain bearing bushes, with plastic or white metal bushes as options on sizes up to 630. Sizes 2.5 to 630 use a two-part housing; sizes 730 to 3150 use a three-part housing with a flange cover.

The KRACHT KF series accepts a wide choice of shaft seals: single, double or triple radial lip-type seals in NBR or FKM, mechanical seals with or without quench connection, a version without shaft sealing, and a magnetic coupling for sizes 2.5 to 630 where absolute tightness is needed. Sizes 2.5 to 630 mount on a DIN flange with a cylindrical ISO R775 shaft end, while larger sizes use SAE or EN 1092 flange connections. Pressure relief valves D (sizes 2.5 to 630) or B (sizes 730 to 3150) can be mounted on the housing, with T and U valves for selected mid sizes.

Key Features

These are the points that make the KRACHT KF series flexible across very different duties:

• Thirty-plus nominal sizes in the KRACHT KF series allow the pump to be matched closely to the flow demand without oversizing the drive.
• Helical gearing keeps pressure pulsation and noise low, and the noise-optimised option from size 4 handles media with entrained air.
• Viscosities from 12 up to 100,000 mm²/s are permitted for sizes up to 630 and up to 20,000 mm²/s for sizes 730 to 1500.
• Media temperature reaches −20 to 150 °C with FKM seals, with low-temperature and high-temperature seal options on request.
• Multiple pumps in the KRACHT KF series (KF + KF or KF + KP) share one drive and keep circuits hydraulically separated.
• KRACHT KF series motor-pump units can be supplied with IEC motors, air motors, gear motors, hydraulic motors, ATEX motors or marine-approved motors.
• Explosion-protected versions under directive 2014/34/EU cover gas zones 1 and 2 and dust zones 21 and 22.
• Pipe-mounted SPV, DV, HVF and DBD valves from the same manufacturer complete the circuit protection.

Industrial Applications

KRACHT describes the family for lubricating oil supply to marine gearboxes, wind turbines and compressors, pre-lubrication and main lubrication of diesel engines, oil delivery in filter systems and fuel delivery. In Oman these duties appear in power and desalination plants, in marine and offshore service at the ports, in oil and gas facilities, and in the compressor stations and industrial zones of Sohar and Salalah. The KRACHT KF series also suits hydraulic oil circulation and lubrication skids built by regional panel and skid fabricators.

Alongside the KRACHT KF series, Seven Star LLC also supplies the KRACHT KP series internal gear pump for higher pressure hydraulic duty, the KRACHT SPV 10 L1G 1 A 12 pressure relief valve for pipe-mounted circuit protection, and the KRACHT VCM gear flow meter for volumetric measurement. Having these items in one supply chain simplifies commissioning of a complete pumping and protection package.

Also available from the same manufacturer: KRACHT KF-F fuel gear pump series and KRACHT DV B pilot-controlled pressure relief valve.

Technical Specifications

The table gives typical family data for the KRACHT KF series from the manufacturer catalog for KF 2.5 to 3150.

Request a Quote for KRACHT KF series

For the KRACHT KF series, send Seven Star LLC the fluid, viscosity range, operating temperature, required flow and pressure, shaft seal preference and drive details. Our team will prepare a formal RFQ for Oman and the GCC, confirm current availability and lead time and supply the KRACHT catalog so that your engineers can verify dimensions, type keys and valve options before ordering.