Thermal conductivity vacuum gauge and thermal compensation assembly
The present disclosure relates to a thermal conductivity vacuum gauge assembly. The assembly comprises a body defining an internal chamber for receiving working gas and a heater element disposed within the chamber. The body is defined by a wall having an outer facing wall surface and an opposing inner facing wall surface. A thermal compensation element is enclosed within the wall between the outer and inner facing wall surfaces. The present disclosure also relates to a thermal conductivity vacuum gauge including the assembly.
1 . A thermal conductivity vacuum gauge assembly comprising:
a body defining an internal chamber for receiving working gas, wherein the body is defined by a wall having an outer facing wall surface and an opposing inner facing wall surface;
a heater element disposed within the chamber;
a thermal compensation element enclosed within the wall between the outer and inner facing wall surfaces; and
a printed circuit board that the thermal compensation element is mounted to, wherein a first portion of the printed circuit board is enclosed within the wall between the outer and inner facing wall surfaces and a second portion of the printed circuit board protrudes out from the wall.
2 . The assembly of claim 1 , wherein the thermal compensation element is a resistance temperature detector (RTD).
3 . The assembly of claim 1 , wherein the thermal compensation element is a thermistor, for example, a positive temperature co-efficient (PTC) thermistor or a negative temperature co-efficient (NTC) thermistor.
4 . The assembly of claim 1 , wherein a cavity is enclosed within the wall between the outer and inner facing wall surfaces, and the thermal compensation element is disposed within the cavity.
5 . The assembly of claim 1 , wherein the second portion includes an electrical connector for connection to a control circuit.
6 . The assembly of claim 1 , wherein:
the body extends along a longitudinal axis between a base and a top and has a sidewall extending between the base and the top; and
the thermal compensation element is enclosed within the sidewall.
7 . The assembly of claim 6 , wherein a cavity within which the thermal compensation element is disposed extends axially through the sidewall to an opening at the top.
8 . The assembly of claim 6 , wherein the first portion of the printed circuit board is enclosed in the cavity and the second portion of the printed circuit board protrudes axially out from the top.
9 . The assembly of claim 6 , wherein the base defines an inlet passage in fluid communication with the chamber, and includes a radially extending flange with a recess therein for receiving a seal.
10 . The assembly of claim 9 , wherein the base includes a filter element disposed across the inlet passage for filtering the working gas.
11 . The assembly of claim 1 , wherein the heater element is a filament for heating by an electrical power source.
12 . A thermal conductivity vacuum gauge comprising:
the assembly of claim 1 ; and
a housing receiving and at least partially surrounding the body.
13 . The vacuum gauge of claim 12 , wherein the housing includes a control circuit for providing electrical control of the heater element and the thermal compensation element.