Determining the Flow-Pressure Properties of Lubricating Grease at Low Temperatures

With MINITEST FFK, the flow-pressure properties of lubricating grease can be automatically determined at low temperatures down to −50 °C using the Kesternich test. The original and time-consuming approach is completely automated and the measuring range is expanded well below the original one, leading to a significantly enhanced test precision.

The use of a huge and expensive cryostat is eliminated by a powerful two-stage Peltier element. The testing principle is based on the required pressure accumulation to push an amount of grease via a standard test nozzle at a preset temperature.

Advanced Technology

In MINITEST FFK, the original manual and lengthy approach is completely automated. The measuring range is expanded well below the original test approach.

Temperature control is carried out using Peltier elements, thereby avoiding the use of a huge and expensive cryostat. There is no need for further accessories.

Sample Handling

A layer of to-be-tested grease is applied on a glass plate without air bubbles. The measuring nozzle is just pressed onto the lubrication grease layer a few times until it is filled with grease. After that, the nozzle is inserted into the thermostatically controlled metal block of the tester and the chamber is air sealed.

Test Parameters

The equilibrium time and the test temperature are programmed. Additionally, for each step, the estimated flow pressure and the pressure increase. For high flow pressures, an initial pressure greater than barometric pressure can be set to speed up the measuring time.

Measuring Procedure

For each step, the equilibrium time, test temperature, estimated flow pressure, and the pressure increase are programmed. For high flow pressures, an initial pressure more than the barometric pressure can be set to speed up the measuring time. The test is carried out fully automatically. Upon reaching the test temperature, the equilibrium time of up to two hours is commenced. After the equilibrium time, the pressure over the sample nozzle is increased gradually until the pressure drops abruptly, signifying that the grease is pressed through the nozzle. Once the test is over, the last pressure value is displayed as the flow pressure according to Kesternich.

Applications

Measuring flow properties of lubrication grease at low temperature is of huge importance for central lubrication systems of machinery and vehicles. This property can best be measured with the help of the Kesternich method.

This test method is ideal for temperatures at which grease does not leak out of the test nozzle.

MINITEST FFK is an instrument for determining the flow pressure of lubricating greases at temperatures down to −50 °C (−58 °F).

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