Thermal conductivity pressure gauge with heated chamber wall
AssigneeMKS Instruments, Inc.
InventorsGerardo A. Brucker, Timothy C. Swinney
Life of this patent
Estimating the term…
Abstract
A Process Critical Thermal Conductivity Gauge (PCTCG) instrument relies on gauge chamber wall above-ambient-temperature-control (AATC) to provide improved accuracy and thermal stability with reduced and linearized temperature coefficients. A sensor resistor is exposed to gas pressure in a gauge chamber. AATC is provided by control of a heater that heats a chamber wall to control temperature difference between the sensor resistor and chamber wall. An example application of this technology is to end-point detection in lyophilization where the TCG is used to track partial pressures of water in binary gas mixtures.
Claims34
A thermal conductivity pressure gauge comprising:
- a sensor resistor;
- a sensor chamber having a chamber wall spaced from the sensor resistor;
- a heater configured to heat the chamber wall;
- and
- electronics configured to, during a process, apply power to the sensor resistor and determine pressure of gas in the sensor chamber based on a relationship between resistance of the sensor resistor and applied power and apply power to the heater to heat the chamber wall to control temperature difference between the sensor resistor and the chamber wall, the electronics being further configured to, between process runs, elevate temperature of the chamber wall to dry the chamber wall.
A method of thermal conductivity pressure measurement comprising:
- providing a sensor resistor within a chamber having a chamber wall spaced from the sensor resistor;
- heating the chamber wall to control temperature difference between the sensor resistor and the chamber wall;
- and
- during a process, applying power to the sensor resistor and determining pressure of gas in the chamber based on the relationship between resistance of the sensor resistor and applied power, and
- between process runs, elevating temperature of the chamber wall to dry the chamber wall.
A thermal conductivity pressure gauge comprising:
- a sensor resistor;
- a sensor chamber having a chamber wall spaced from the sensor resistor;
- a heater configured to heat the chamber wall;
- a baffle across an opening in the chamber wall, the baffle being thermally connected to the chamber wall and configured to block contaminants and radiation from the chamber;
- and
- electronics configured to apply power to the sensor resistor and determine pressure of gas in the sensor chamber based on the relationship between resistance of the sensor resistor and applied power, and to apply power to the heater to heat the chamber wall to control temperature difference between the sensor resistor and the chamber wall.
A method of thermal conductivity pressure measurement comprising:
- providing a sensor resistor within a chamber having a chamber wall spaced from the sensor resistor;
- heating the chamber wall to control temperature difference between the sensor resistor and the chamber wall;
- blocking contaminants and radiation from the chamber with a baffle across an opening in the chamber wall, the baffle being thermally connected to the chamber wall;
- and
- applying power to the sensor resistor and determining pressure of gas in the chamber based on the relationship between resistance of the sensor resistor and applied power.
A thermal conductivity pressure gauge comprising:
- a sensor resistor;
- a sensor chamber having a chamber wall spaced from the sensor resistor;
- a heater configured to heat the chamber wall;
- and
- electronics configured to apply power to the sensor resistor and determine pressure of gas in the sensor chamber based on the relationship between resistance of the sensor resistor and applied power, and to apply power to the heater to heat the chamber wall to control temperature difference between the sensor resistor and the chamber wall;
- wherein the chamber wall and sensor resistor are removable from an assembly of the heater and electronics and are inserted into the heater as sensor leads are plugged into the electronics to make electrical connection between the sensor resistor and the electronics.
A method of thermal conductivity pressure measurement comprising:
- providing a sensor resistor within a chamber having a chamber wall spaced from the sensor resistor;
- inserting the sensor resistor and chamber wall into a heater as sensor leads are plugged into electronics;
- heating the chamber wall with the heater to control temperature difference between the sensor resistor and the chamber wall;
- and
- with the electronics, applying power to the sensor resistor and determining pressure of gas in the chamber based on the relationship between resistance of the sensor resistor and applied power.
Dependencies are inferred from the claim text.