KRACHT KF T15/T25 Gear Pump with T-Valve and Tank Port

KRACHT KF T15/T25 gear pump with T-valve and separate tank connection

The KRACHT KF T15/T25 is a KF series gear pump equipped with the T-valve, an attached, directly controlled relief valve that has its own connection to the storage tank. Fluid leaving through the valve does not go back into the pump suction. It flows straight to the tank and carries heat with it. That is the practical difference from the D-valve, and it is why the T option exists for circuits where some flow must be dumped for longer than a few seconds. Seven Star LLC supplies KRACHT KF pumps in Oman and the GCC as an independent supplier in Muscat.

The T-valve is offered only on five nominal sizes of the KF family: 32, 40, 50, 63 and 80 cm³/rev. In the type key the letter T is followed by the top of the setting range: T15 covers 0 to 15 bar and T25 covers 15 to 25 bar. A further code after the valve selects the viscosity range, which is specific to the T-valve and does not appear on the D-valve.

KF T15/T25 technical specifications

How the T-valve of the KF T15/T25 differs in operation

Inside the valve housing the discharge pressure acts against an adjustable setting. When pressure exceeds it, the valve opens a path to the tank connection, where the operator has fitted a return line. Because the oil leaves the pump casing, the heat of recirculation stays out of the gear set. KRACHT describes the valve as adapted-damped, giving very good control behaviour and vibration-free running at every operating point of the pump. The damping is what lets the valve avoid chatter, a typical problem of direct-acting relief valves on pulsating gear pumps.

Because the T-valve is tuned to the fluid, the viscosity code matters on every KF T15/T25 order. A valve ordered for 12 to 300 mm²/s will behave differently with a heavy fuel or a cold gear oil at 2000 mm²/s, which is why the type key offers three viscosity bands. State the viscosity at the lowest and highest operating temperature when you enquire.

Compatible parts and related variants of KF T15/T25

The KF T15/T25 is a sibling of the KF D15/D25 (internal return, all sizes) and the KF U/U2 universal valve. If the circuit needs a constant bypass at very high flow, KRACHT also lists the SPV pipeline slide valve and the hydraulically piloted DV B, DV S and DV R valves, which are installed in the line rather than on the pump. For sizes outside 32 to 80 and a bypass requirement, an in-line valve is the correct route because the T-valve is not available there.

The pump can still be combined with the usual shaft-seal options, with the DIN flange or mounting angle, and with or without an outboard bearing. Sealing types, from the single radial lip seal in NBR, FKM or PTFE to mechanical seals with FFKM secondary seals, are chosen by the number in position 5 of the type key.

Selection checklist for KF T15/T25

• Confirm that a nominal size between 32 and 80 cm³/rev meets the flow; the T-valve is not offered outside this range.
• Pick T15 or T25 from the working pressure and the highest pressure at which the valve must open.
• Select the viscosity code from the real fluid and temperature range.
• Plan, for the KF T15/T25, a return line of adequate diameter from the valve tank connection to the reservoir, below the fluid level, with no restriction or shut-off valve.
• Choose rotation R or L, DIN flange or mounting angle, and seal type.
• Check material compatibility of seals with the fluid.
• Decide on ATEX where required for the area.

Installation and maintenance for KF T15/T25

On a KF T15/T25 the tank line is the item most often forgotten. If the T port is blocked or throttled, back pressure adds to the valve setting and the valve opens late. Route the return line downward where possible and keep it short. Fill the pump and suction line before starting, keep the suction pressure above –0.4 bar, and verify the direction of rotation before coupling.

During commissioning, raise the system pressure slowly and watch the tank return. A small stream at the valve opening pressure is normal. Persistent flow far below the setting means that the valve seat is worn or contaminated, and flow that appears suddenly with noise points to particles in the fluid. Because the T-valve on the KF T15/T25 exists to dump flow, its tank return is a useful diagnostic: a rising return temperature shows how much of the pump delivery is being relieved, and therefore how much power is wasted as heat.

Applications in Oman and the GCC

The KF T15/T25 suits duties with a sustained bypass: burner and fuel-oil supply with a pressure regulating loop, lubrication of large gearboxes and turbine auxiliaries where flow varies with load, and hydraulic power packs on process valves. On a KF T15/T25 unit hot ambient conditions raise the baseline oil temperature, so the heat carried to the tank by the T-valve is an advantage in summer. Where the tank sits in the sun, check the oil bath temperature against the seal rating. Sites with dusty air should have breather filters on the reservoir.

T-valve variant comparison

Information to send with an RFQ for KF T15/T25

• Nameplate type code, or nominal size, rotation, mounting and seal choice.
• Valve band, T15 or T25, and the viscosity code.
• Fluid, temperature range and minimum and maximum viscosity.
• Operating flow and pressure, and how much bypass flow is expected.
• Drive power and speed, coupling type, and location in a hazardous area if any.
• Quantity and delivery site.

Documents and quotation

The manufacturer data sheet for the KF 2.5 to 630 series, covering the pump without valve, with D-valve and with T-valve, is attached on this page and contains the type key and the T-valve limits.

Send the KF T15/T25 part number or your duty data and we will confirm availability, lead time and a quotation for the KF T15/T25 in Oman and the GCC.