GB1178818A - Automatic Flash Point Measuring Apparatus - Google Patents

Abstract

1,178,818. Measuring flash point. PRECISION SCIENTIFIC CO. June 13, 1968 [June 14, 1967], No.28178/68. Headings G1D and G1N. In the automatic determination of the flash point of a liquid in which the liquid is continuously supplied to a heating chamber 14, Fig.1, where it is heated at a controlled rate so as to produce a vapour which rises into a flash chamber 17 together with air from an inlet 20, and in which the airvapour mixture is ignited at the flash point by a spark periodically produced between electrodes 24, 25', detection by a thermocouple TCV of the sudden increase in temperature consequent upon ignition causes the liquid to be diverted by a solenoid-operated valve 12 from the heating chamber 14 into the air inlet 20. This arrangement causes rapid cooling of the flash chamber 17 before the next test cycle commences. The heater 15 of the heating chamber is supplied with a constantly increasing voltage from a motor driven variable transformer (35, Fig.4, not shown), and the liquid passes through the chamber between an inlet 10 and an outlet 23. The temperature of the liquid is detected by a thermocouple TCL and indicated on a recorder 26. When the flash point is reached, the output pulse from thermocouple TCV is supplied to a magnetic amplifier (33) and causes de-energization of the heater. At the same time a reverse D.C. voltage from a converter (43) is applied to the recorder to cause an abrupt drop in the recorded trace, the peak temperature recording being the flash point of the liquid. Other operations consequent on the output pulse from thermocouple TCV are the rotation of valve 12 to divert the liquid from the heating chamber, the disconnection of the electrodes from the pulse generator and reduction of the heater voltage by reversal of the motordriven variable transformer. To prevent an excessive temperature rise in the heating chamber driving a test, a thermocouple TS2 is connected to a shut down circuit.