Radiator Selection: A Checklist for Choosing the Right Oil Cooler

Selecting a radiator does not mean buying the largest product in the catalog. It means balancing the heat your system rejects against the conditions of the operating environment. The steps below show, in order, which data you need to collect to choose the right radiator for your hydraulic or oil cooling circuit.

1. Determine the heat load to be rejected

The first input is the amount of heat the radiator must remove from the system. This value is usually expressed in kW or kcal/h; roughly, 1 kW corresponds to 860 kcal/h.

You typically estimate the heat load from the machine manufacturer's data, from system efficiency losses, or from a measured oil temperature difference. If you are unsure, the safest approach is to send your calculation, together with its assumptions, to the technical team.

2. Write down the oil flow rate and temperature target

The oil flow rate through the radiator (L/min) and the inlet and outlet temperatures you are aiming for directly affect capacity. If the flow rate exceeds the maximum the radiator allows, pressure drop increases; if it is too low, heat transfer is inefficient. Always check the maximum flow rate limit in the catalog.

The type and fluidity of the oil also matter. An oil that flows thickly when cold can create higher pressure in the circuit than expected at first start-up.

3. Check the pressure values

A radiator's maximum working pressure and its test pressure are not the same thing. Your system's normal working pressure and any sudden pressure peaks must stay below the radiator's working pressure limit. Even for radiators connected to the return line, allow for the shocks created when valves open and close.

For example, the published values for Safkan's fan-cooled radiators are 15 bar working pressure and 24 bar test pressure, while the compressor radiators are listed at 15 bar working pressure, 22 bar test pressure and a maximum temperature of 120 °C.

4. Collect the environment, space and connection details

• Ambient temperature: An air-cooled radiator can only bring the oil down to a level above the temperature of the cooling air. Use the hottest summer condition as your basis.
• Space and dimensions: The area reserved for mounting and the clearance that lets air flow in and out freely. Recirculation of hot air reduces performance.
• Connection: Inlet and outlet diameter, thread type, and the hose or pipe standard.
• Environmental contamination: If there is dust, oil vapor or moisture, fin spacing and ease of cleaning become important.

5. Choose the fan and supply voltage

For fan-cooled models, supply voltage is a selection criterion. Mobile machines usually use DC (12 V or 24 V) taken from the vehicle battery, while fixed installations use AC (220 V or 380 V) from the mains. In Safkan's fan-cooled range, every model group is offered in both DC and AC versions. For the differences between models, see the article on fan-cooled oil cooler models.

Common selection mistakes

• Choosing by the size of the old radiator alone, without calculating the heat load; the old radiator may already have been inadequate.
• Judging capacity against a mild ambient temperature that is never actually encountered.
• Looking only at average working pressure without considering pressure peaks.
• Not settling the fan voltage at the ordering stage; DC and AC models cannot be used in place of each other.
• Choosing a layout that blocks the front or back of the radiator; insufficient airflow weakens even a well-chosen product.

What to send for a quote or technical support

Putting the following information together in a single message reduces the number of back-and-forth emails:

1. Application type and machine information
2. Heat load to be rejected (kW or kcal/h) and how it was determined
3. Oil type, flow rate, inlet temperature and target temperature
4. Working pressure and possible pressure peaks
5. Highest ambient temperature and operating environment
6. Available space and connection dimensions
7. Fan voltage (DC or AC) and quantity

If you want to refresh the operating principle first, the article on cooling in hydraulic systems and how a radiator works is a good starting point. For product selection and technical information based on the data you have, contact us and we will complete any missing data together.