Hydraulic Oil Cooling System - Hydraulic Oil Cooler
These oil coolers are also suitable for heat transfer fluids, lubricating and quenching oils. They are high-quality products incorporating the best materials and the latest technical features. The tube stack is fully floating, so that thermal stresses are minimised and it can be easily removed, should cleaning be necessary.
We have listed on page 7 some typical examples of oil cooler performance. This information is only intended to provide a general basis for selection. Graphs are available which show how heat dissipation and pressure losses vary with oil and water flow. computer, the size of oil cooler required from the following information: Alternatively, we can select by:
Oil type or its viscosity at a specified temperature Oil flow | cSt at °C l/min |
Required oil outlet temperature | °C |
Heat to be dissipated | kW |
Temperature of cooling water | °C |
The oil coolers should be mounted as shown below to ensure that they operate full of water and should be connected for counterflow. If the water control valve is used, it should be of the modulating type and fitted on the inlet side, so that the cooler is not unnecessarily pressurised with water when the system is shut down. Care must be taken not to exceed the recommended water flow rates and the pH of the water should be between 7.2 and 7.8. For hydraulic applications, the oil cooler should be in the return pipe to tank as shown in the diagram, but on installations where this is subject to violent fluctuations in flow and pressure, it may be advisable to connect the cooler into a separate circuit with its own pump. It is good practice for the oil pressure in the cooler to be higher than the water pressure, so that should a leak occur, the oil will not be contaminated with water.

The standard seal material is nitrile. We can, at extra cost, supply seals compatible with the various fire resistant fluids. To specify these seals, a suffix should be added to the oil cooler type number as follows: EP (Ethylene Propylene), VT (Viton). When ordering replacement seals, change the suffix NT in the seals part number as required.
The standard cast iron end covers are satisfactory with fresh water. For use with contaminated fresh water or sea water, we can, at extra cost, supply bronze end covers. To specify this material, change the 4 figure section of the type number as follows: 1425 to 3875, 1426 to 3876, 1427 to 3877, 1428 to 3878, 1658 to 3879, 1661 to 3881 and 1669 to 3880.
We can supply coolers suitable for oil temperatures of up to 150°C. To specify this type, change the 4 figure section of the type number as follows: 1425 to 3145, 1426 to 3146, 1427 to 3147, 1428 to 3148, 1658 to 3149, 1661 to 3152 and 1669 to 3150.
In addition, we have a limited range of oil coolers suitable for use with oil or heat transfer fluids up to 200°C. These oil coolers have a cast iron shell, viton seals and a special tube stack. To specify this type, change the 4 figure section of the type number as follows: 1425 to 3635, 1426 to 3636, 1427 to 3637 and 1428 to 3638. This particular option is only available with coolers marked Δ in the rating table on page 7.
We have a limited range of oil coolers suitable for underground mining applications and water pressures up to 35 bar. These oil coolers have a cast iron shell, viton seals and a special tube stack with cupro-nickel tube. To specify this type, change the 4 figure section of the type number as follows: 1425 to 3425, 1426 to 3426, 1427 to 3427 and 1428 to 3428. This option is only available with coolers marked Δ in the rating table on page 7.
Please contact us for applications not covered by our published information. We can also advise on the best method of installing coolers, particularly for unusual or critical applications. If a single unit is too small, multiple units can be connected either in series or in parallel according to the oil flow rate. We can also supply the PK range of coolers with 4” ports and special high flow tube stacks suitable for oil flow rates up to 1400 l/min.


Typical examples of oil cooler performance with an oil outlet temperature of 50°C and a water inlet temperature of 25°C.












No oil cooler manufacturer can guarantee that his products will have an indefinite life and for this reason, we suggest that the cooling system is designed to minimise any damage caused by a leaking oil cooler.
This can be achieved as follows:
- The oil pressure should be higher than the sea water pressure, so that in the event of a leak occurring, the oil will not be contaminated.
- When the hydraulic system is not being used, the coolers should be isolated from sea water pressure.
- The sea water outlet pipe from the cooler should have a free run to waste. Stainless steel sea water pipes and fittings should not be used adjacent to the oil cooler.
- Ensure maximum stated flow rates are not exceeded.