Vacuum Meter for Total Pressure Measurement

The right vacuum gauge for every application - selected according to the required accuracy depending on the pressure range and physical measuring principle, equipped with optimized accessories and smooth communication via preferred interfaces.

Choosing the right vacuum gauge for your application

Each vacuum gauge is based on a different physical principle and is more suitable for certain applications than others. The pressure range of a vacuum gauge is determined by the measuring principle used as well as the design and structure of the measuring device.

The criteria for selecting the vacuum gauge depend on the pressure range to be detected as well as various general conditions:

  • Measuring range

  • Required accuracy

  • Gas composition (inert or corrosive)

  • Environmental conditions such as ionizing radiation, strong magnetic fields

  • Type of interface (analog or digital signal)

In addition to the actual measuring devices, there are accessories that simplify handling such as display, evaluation and documentation. In principle, only the total pressure can be determined with gauges; mass spectrometers are used for partial pressures.

In which pressure range do you want to measure the total pressure and with what accuracy?

If only a process condition with a small pressure range is to be monitored, a measuring principle can be selected according to the following list based on the pressure range. The corresponding accuracies and reproducibility are also listed. Depending on how precise the measurements need to be, the accuracy requirements and therefore the cost of the measuring device will vary.

Pirani measuring principle

  • Measuring principle: Thermal conductivity of gases

  • Pressure range: Rough vacuum to high vacuum (1 · 103 to 1 · 10-4 hPa)

  • Accuracy requirement: Low to medium

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Piezo-resistive measuring principle

  • Measuring principle: Change in the resistance of the strain gauges with pressure

  • Pressure range: Rough vacuum to fine vacuum (1 · 103 to 1 · 10-1 hPa)

  • Accuracy requirement: Medium

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Capacitive measuring principle

  • Measuring principle: Change in capacitance between electrodes

  • Pressure range: fine vacuum to high vacuum (1 · 103 to 1 · 10-5 hPa)

  • Accuracy requirement: High

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Cold cathode measuring principle

  • Measuring principle: Electron emission from a cold cathode

  • Design: Penning, inverted magnetron

  • Pressure range: high vacuum to ultra-high vacuum (1 · 10-2 to 1 · 10-11 hPa)

  • Accuracy requirement: Medium

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Hot cathode measuring principle

  • Measuring principle: Electron emission from a hot cathode

  • Design: Bayard-Alpert, extractor system

  • Pressure range: Ultra-high vacuum to extremely high vacuum (1 · 10-2 to 1 · 10-12 hPa)

  • Accuracy requirement: High

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Optimization of vacuum systems through strategic combinations of measuring principles

For larger ranges, it may be necessary in some vacuum systems to combine several types of vacuum gauges with the same and/or different measuring principles. This can be implemented either by integrating several individual measuring gauges into one system or by working with combination gauges. Depending on the requirements and combination, the desired accuracy can be determined in the corresponding pressure ranges in order to control the entire sequence, from evacuation of the chamber through to subsequent flooding. The available combinations are Piezo/Pirani, Pirani/capacitive, Pirani/hot cathode and Pirani/cold cathode.

Available flange shapes: ISO-KF (standard) and CF flanges are most commonly used. Some of the gauges are available with an easily sterilizable TriClamp flange, VCR or thread.
Depending on the application temperatures, vacuum gauges with extended flanges are also available, which increase the distance to the temperature.

How would you like to evaluate your vacuum gauge?

Vacuum gauges work by detecting changes in pressure and converting those changes into electrical signals that can be interpreted by the user. There are two types of signals that vacuum gauges can generate: analog and digital signals. In addition to the evaluation signals, there are various interfaces; the selection of both depends on the specific application requirements. Is real-time data exchange necessary, are multiple measuring devices integrated, and is user-friendliness a priority?

The required hardware and software as well as the complexity and maintenance effort of the interface should also be taken into account.

The two standard device series DigiLine and ActiveLine are active vacuum meters, which means the electronic components are in the same housing as the actual measuring equipment.

DigiLine: Devices with digital signal output

The DigiLine transmitters are designed for industrial and research applications that require easy-to-install and reliable total pressure measurement. The series covers the technically interesting vacuum range with the measuring principles of Piezo, Pirani, capacitive, hot cathode and cold cathode sensors. All transmitters have an RS-485 interface via which up to 16 measuring points can be connected to a controller.

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ActiveLine: Devices with analog signal output

The ActiveLine series offers a large selection of vacuum meters with different measuring principles and classic analog output. The series covers the technically interesting vacuum range from ultra-high vacuum to the overpressure range. The pressure-proportional output voltage of the transmitters can be displayed as pressure by the three control units or read in via analog inputs for further processing in control systems.

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Vacuum gauges for special requirements

There are special requirements that occur so frequently that Pfeiffer Vacuum has its own model series for them. These include passive vacuum gauges.

ModulLine: for total pressure measurement in areas with ionizing radiation

These gauges do not contain any electronics, which makes them suitable for use in places with high levels of radiation, among other things.

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Hand-held measuring devices and pressure gauges for mains-independent use

There are two different battery-operated hand-held measuring devices with displays. The TPG 201 works according to the heat conduction principle (Pirani). The TPG 202 also has a piezo-resistive pressure sensor for the upper pressure range.

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Integrated sensors for system integration

Regardless of whether you want to integrate a vacuum measuring device into a complex system or monitor a single pump: the integrated sensors require little space and offer a simple connection to the pump electronics.

Diverse filament options for optimal vacuum gauge performance

Depending on the atmosphere in which the vacuum gauge is used, different filament materials can have a different service life. We therefore offer different versions of the relevant vacuum gauges, for example made of nickel, tungsten, tungsten/iridium with yttrium oxide coating (Y2O3 ) or platinum/rhodium. Not sure what works best for you? Just get in touch with us.

Custom solutions for unique needs

In order to respond to our customers' wishes, we also offer some vacuum gauges that do not fit into our standard series. These include, for example, the CLR gauges of the CLR 39x type, which are specifically designed for use on steam-sterilizable freeze dryers. The sensor of the temperature-controlled capacitive vacuum gauges is heated to a constant 160 °C, which enables very precise pressure measurement in the range from 10 hPa to 1 · 10-3 hPa. These gauges are controlled via PLC and are optionally available with an easily sterilizable TriClamp flange.

Packages with everything you need to operate vacuum meters

Complete measuring equipment consists of a transmitter, control unit and cables. The latter are available in various standard lengths and are suitable for different temperature ranges. You will find the right selection for the gauge in the selected product and also via the accessories.

We offer attractive packages for the most common products, but individual configuration is also possible, for example if you plan to expand the system in the future. And if you are unsure what is the right measurement solution for you, please contact your sales contact to receive support in selecting the right products for you.

Cleaning and calibration for reliable measurement values

Some vacuum gauges become more contaminated than others, primarily due to the process in which they are used. Proper cleaning can extend their lifespan. Would you like to know how this works? Find out more in our whitepaper.

In addition, measuring equipment must be regularly calibrated with standards because the quality of a process depends on how accurately the measured values are maintained. This is required by the ISO 9001 quality management standard, for which we offer a calibration service and calibration pumping stations if you wish to carry out the calibration yourself.

Whitepaper:
How Do I Clean Vacuum Gauges Correctly?