David H Hultgren Deceased4577 Dewsbury Ct, Lakeland, FL 33801

4722611, Feb 2, 1988

Mar 13, 1986

6/839321

David H. Hultgren - Buzzards Bay MA

Union Carbide Corporation - Danbury CT

G01N 2518
G01N 2520
G01N 2500

374 43

An apparatus for testing the quench-cooling properties of a liquid quenchant includes a thermistor that is adapted to be immersed in the liquid to be tested. An electrical potential is applied across the thermistor, which is contained in one leg of an electrical bridge circuit. A first timer controls the duration of time during which the voltage is applied to the bridge circuit. A voltmeter is connected across the bridge circuit for indicating changes in the bridge balance due to changes in the resistance of the thermistor. The thermistor changes resistance in accordance with the thermal conductivity of the liquid in which it is immersed. Therefore, the quenchant properties of the liquid being tested are determinable by comparing the voltage output of the bridge when the thermistor is immersed in the test liquid with at least one reference voltage output obtained by immersing the thermistor in a reference liquid quenchant. Each test is conducted for the same amount of time, which is controlled by the timer. A process is provided for testing liquid quenchants, particularly used quenchants that can be restored to their original properties by the addition of polymer quenchant additives, or solvents such as water.