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Composing Vacuum Measurement

Vacuum measurement & control

With a wide range of vacuum systems and processes comes a need to measure the vacuum performance.

The instruments used for measuring the pressure within this wide range are called vacuum gauges and measure from above atmospheric pressure (~ 2000 mbar (1500 Torr)) down to 10-12 mbar/torr. No single sensor technology is capable of measuring across this range.

Therefore, a variety of different vacuum gauges are available, each with their own characteristics and ability to measure over multiple decades of vacuum. In order to widen the measurement range, it is now common to combine multiple technologies into a single gauge to reduce the connections needed in a system.  

A main way to differentiate vacuum gauge types is by how they measure the gas: direct or indirect pressure measurements.

  • In the case of direct (or gas independent) pressure measurements, the readings obtained through the vacuum gauge are independent of the type of gas and the pressure given is always the true pressure of the system. Often relying on a mechanical deflection of a membrane, these are capable of measuring from above atmospheric pressure down to 10-4 mbar/torr. These gauge types will give you high accuracy over a short range and are typically very robust. 
  • In the case of indirect pressure measurements, the pressure is determined as a function of a pressure dependent property of the gas (thermal conductivity, ionization probability, for example). These properties do not only depend on the pressure, but also on the molar mass of the gases. Therefore, these are also known as gas dependent. The readings usually relate to air or nitrogen as the measurement gas. For the measurement of other vapors or gases the corresponding correction factors must be applied for the true pressure of the system. These gauges are capable of pressure measurement over a much wider range (atmospheric pressure to 10 x 10-12 mbar dependent on type/combination), with the tradeoff being a lower level of accuracy. 

Another common decision point on vacuum gauges is active or passive, with this option being available in our broad range vacuum gauges.

  • Active gauging is where the gauge head (sensor head) is combined with the electronics required to control and output a signal, enabling easy integration to a system. 
  • Passive gauging is where the gauge head is separated from the electronics, which are then kept separately in a dedicated controller. The advantage of this is that they can be used in environments where the electronics would not be able to function, such as high radiation environments, and the separate controller can be removed from said environment.

Gauges and controllers

Broad range vacuum gauging

Robust, reliable, and accurate pressure measurement across a broad pressure range.

  • THERMOVAC TTR/TR series - perfect for monitoring standard primary/backing pump pressures. 
  • PENNINGVAC PTR/PR series – enabling measurement in the high vacuum region, these can be described as full range gauges.
  • IONIVAC ITR/IE series – further extending the vacuum range into ultra high vacuum pressures.

Precision vacuum gauging

For the highest levels of accuracy and repeatability, in the harshest environments, these are perfect for detailed system control.

  • CERAVAC CTR vacuum gauges - top of the range of capacitance manometer gauges.
  • DI/DU vacuum gauges - a slightly lower level of accuracy, but suitable for dirty/damp/dusty environments.

Vacuum pump and gauge controllers

Gives you the ability to display pressure, and integrate its measurement into a wider control system. We have a range of controllers to choose from depanding on your specific requirements.

Portable and mechanical vacuum gauging

Having a gauge that has an integrated display and is battery powered enables you to measure wherever and whenever. Mechanical dial gauges are ideal when you just need an indication that you are pulling vacuum, rather than precise measurements.

IONIVAC hot cathode ionization vacuum gauge

Hot cathode ionization differs from cold cathode in that it has a hot filament emitting ions inbuilt into the sensor head. This technology is capable of measuring from medium to ultra-high vacuum pressures (10-12 mbar/torr), the trade off being a sensor head that requires more protection, and with its more complex design comes a higher cost of ownership.

As with cold cathode technologies, they stop measuring ~10-2 mbar/torr, therefore are normally combined with an integrated pirani to provide full range measurement in a single gauge.

Also there are different versions of the hot cathode technology, with the main types being Bayard-Alpert (ITR or IE 414) and extractor (IE 514). The extractor technology offers the lowest pressure measurement with the ability to measure to 10-12 mbar/torr
 

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