Principles of Operation
Thermocouple gauges measure pressure in terms of the amount of heat that gas will conduct away from a hot wire. The sensing element is a combination heater and thermocouple. Cross-shaped, it is formed by joining two short resistance wires of different compositions, a method of construction which gives excellent shock resistance and yet provides the minimum mass required for fast response. With a fixed heater power, the temperature of the junction, which depends on the conductivity of the gas, is indicated by the voltage output of the thermocouple. As the pressure drops, the thermocouple gets hotter and its output increases. Readout is accomplished on a millivolt meter calibrated to indicate pressure.
The Model 531 Thermocouple Vacuum Gauge provides continuous and accurate indication of total pressure from 1 x 10-3 to 2 Torr absolute. Developed to combine rugged dependability and outstanding performance, the 531 offers fast response and low power drain.
Filament Current 165 mA (gives 14 mV across the thermocouple at pressures below 10 -3 Torr) Response Time 3 sec. (10 -3 to 1.0 Torr) Range 1 x 10 -3 to 2 Torr Output 0 to 14mV Heater Resistance 1.4 ohms (approx.) Dimensions 1.21" O.D. x 3" long Connections May be soldered into a system, used with 1/2" '0' ring compression seal or threaded on 1/8" IPS female thread. Cable Connection Octal Base (std.) Casing Nickel-plated mild steel Pins Nickel-iron alloy (Ni 48%, Fe 52%) Volume/Weight 12cc/2oz.
|F0472301||Varian 531 Vacuum Gauge Tube (Finnigan #00105-02000)||EA||0.25||11||$79.00|
|[*L] Standard lead-time for out-of-stock items is approximately two weeks depending on the item.|
|Ordering information. International (non-US) prices available through your local dealer.|
|SIS Catalog Cross Reference|
|Page #||Part Numbers|
|B23 - Thermo* Mass Spec Accessories||F0472301|
|F13 - Thermocouple Vacuum Gauge||F0472301|
Yttria coated filament at start
Yttria coated filament after 16,000 cycles