Teledyne HPM 4/6 General Information, Sensor Electrical Connector, Pressure Measurements

4.0 General Information

Operation of the Hastings gauge sensor (DV-4 or DV-6) is based on a low voltage AC bridge that heats a noble metal thermopile. A change in pressure in the gauge tube alters the molecular collision rate and therefore the thermal conduction of the gas or gas mixture surrounding the thermopile. This causes a temperature shift in the AC heated thermocouples A and B (Fig. 3-1). The resultant temperature shift causes a change in the DC output from couples A and B (which varies inversely with pressure). Thermocouple C provides compensation for transient changes in ambient temperature.

4.1.Sensor Electrical Connector

The thermocouple vacuum sensor tube interfaces with the HPM 4/6 Vacuum Gauge via the octal connector. The Octal connector is “keyed” so that proper connection is assured. Always grip the connector by its cover and not the cable when plugging or unplugging the connector.

Disconnecting gauge tube by pulling on the cable may result in damage to the octal socket and/or cable.

4.2.Pressure Measurements

The HPM 4/6 is shipped from the factory fully calibrated, and will provide immediate and accurate pressure measurements.

1.Plug octal socket on to DV4 or DV6 thermocouple tube.

2.Turn unit on by positioning the slide switch on the side on of instrument case to DV-4 or DV-6 position as required depending on which thermocouple tube is being monitored. The DV4 or DV6 switch position indicators are labeled on the bottom of the unit. Once the slide switch is in the proper position, the display will indicate one of the following:

a.The correct pressure. (Value within range of sensor selected).

b.Pressure over range “1”, where the sensor is at a pressure greater than full scale or the sensor not connected.

Manual: 153-082010_HPM 4-6 Vacuum Gauge Page 7 of 12