Vacuum Gauge Operating and Maintenance Guide
Vacuum gauges measure pressure below atmospheric pressure. They are essential in vacuum systems for processes such as distillation, drying, and coating.
I. Types and Operating Principles
- Bourdon Tube: Suitable for rough vacuum down to about one millibar. Simple, robust, and cost-effective.
- Capacitance Manometer: Measures pressure independent of gas composition. High accuracy from atmosphere to high vacuum range.
- Pirani Gauge: Measures thermal conductivity of the gas, which varies with pressure. Suitable for medium vacuum range.
- Cold Cathode / Penning: Measures pressure through ionization in a magnetic field. Suitable for high and ultra-high vacuum.
- Hot Cathode Ionization: Highest vacuum measurement capability. Uses thermionic emission to ionize residual gas molecules.
II. Operating Procedures
- Select the appropriate gauge type for the vacuum range being measured
- Install the gauge as close to the vacuum chamber as possible for accurate measurement
- Allow the gauge to stabilize after system startup before taking readings
- For thermal conductivity gauges, be aware that readings are gas-dependent and may need correction factors for different gases
III. Maintenance
- Keep gauge connections clean and leak-free
- For ionization gauges, degas the electrodes periodically per manufacturer instructions
- Replace contaminated or aged sensor elements on a scheduled basis
- Calibrate gauges annually or when readings become suspect
