This guide provides an overview of measuring vacuum pressure including suggested vacuum measurement products and question & answers relating to using and selecting vacuum measurement sensors & instrumentation.
Contents
Products
Vacuum range pressure transducers, transmitters, gauges, loggers, calibrators and hand pumps for measuring negative gauge suction or absolute pressures below ambient atmospheric pressure.
Vacuum Pressure Transmitters - Choose vacuum pressure transmitters for measurements over the low vacuum range of 25 to 760 Torr, using a absolute or negative gauge reference vacuum range.
Vacuum, Suction Pressure Data Loggers, Recorders - Vacuum data loggers for recording negative suction pressure or absolute pressure below atmospheric pressure. Log and store vacuum measurements for printing test reports or analysing process trends.
Vacuum, Suction, Negative Pressure Gauges - Vacuum range gauges for measuring absolute vacuum or suction pressures which can be permanently installed or used as a test gauge.
Vacuum Pressure Transducers - These voltage output transducers will provide a linear signal of a few volts that is directly proportional to a specified vacuum range.
4-20mA Output Vacuum Pressure Transmitters
Vacuum pressure transmitter with a 4-20mA 2 wire current loop output for measuring suction pressures relative to atmospheric pressure or absolute zero referenced pressures.
DS200P Sanitary Low Range Pressure Gauge, Switch and Sensor
DMK457 Marine Approved Pressure Transmitter
DMP331i High Accuracy Pressure Transmitter
DMP331P Hygienic Flush Pressure Transmitter
DMK331P Flush Diaphragm Pressure Sensor
DMP343 Low Range Pneumatic Pressure Sensor
LEO3 Current or Digital Output Pressure Gauge
DMP457 Marine Approved Pressure Transmitter
XMPi Process Plant Gauge and Absolute Pressure Transmitter
DPS200 HVAC Differential Pressure Transmitter
DPS300 User Switchable Pressure Range, Volts or Current Output Low DP Sensor
DS200 Combined Pressure Switch, Gauge and Sensor
DS210 Combined Low Pressure Switch, Indicator and Sensor
DPS Low Differential Pressure Transmitter
25 Ed Flame Proof Flush Diaphragm Pressure Transmitter
Voltage Output Vacuum Pressure Transducers
Vacuum Range Pressure transducers with 5 or 10 volt full rnage output signals for measuring partial vacuums of a few mbar or full vacuums up to minus 1 bar (-15 psi).
DS200P Sanitary Low Range Pressure Gauge, Switch and Sensor
DMP331i High Accuracy Pressure Transmitter
DMP331P Hygienic Flush Pressure Transmitter
DMK331P Flush Diaphragm Pressure Sensor
DMP343 Low Range Pneumatic Pressure Sensor
DPS200 HVAC Differential Pressure Transmitter
DPS300 User Switchable Pressure Range, Volts or Current Output Low DP Sensor
DS200 Combined Pressure Switch, Gauge and Sensor
DS210 Combined Low Pressure Switch, Indicator and Sensor
DPS Low Differential Pressure Transmitter
25 Ed Flame Proof Flush Diaphragm Pressure Transmitter
Millivolt Output Vacuum Pressure Sensors
Vacuum range strain gage pressure sensors with mV output signals for measuring pressures below ambient air pressure with a gauge or absolute reference.
Digital Vacuum Pressure Sensors
Vacuum range digital interface pressure sensors for connecting to computer serial bus or other intelligent interface.
33X High Accuracy Digital Output Pressure Sensor
LEO3 Current or Digital Output Pressure Gauge
35X Flush Diaphragm Digital Output Pressure Sensor
Switches for Controlling Vacuum
Pressure switches for starting & stopping equipment or sending an alarm signal at a preset vacuum pressure.
DS200P Sanitary Low Range Pressure Gauge, Switch and Sensor
DS200 Combined Pressure Switch, Gauge and Sensor
DS210 Combined Low Pressure Switch, Indicator and Sensor
901 Prescal Pressure Switch Specification and Data Sheet
Gauges for Measuring Vacuum
Vacuum range pressure gauges with digital readout for measuring absolute vacuum or suction pressures which can be permanently installed or used as a test gauge.
LEO1 (Ei) Digital Pressure Gauge
DS200P Sanitary Low Range Pressure Gauge, Switch and Sensor
LEX1 (Ei) High Accuracy Digital Pressure Gauge
LEO Record (Ei) Pressure Data Logger
Baroli 02 Precision Digital Pressure Gauge
LEO3 Current or Digital Output Pressure Gauge
DM01 Multi-Range High Accuracy Pressure Gauge
LEO 2 (Ei) Digital Manometer
Baroli 05 Industrial Digital Pressure Gauge
DS200 Combined Pressure Switch, Gauge and Sensor
DS210 Combined Low Pressure Switch, Indicator and Sensor
Baroli 02P Low Range Flush Diaphragm Digital Pressure Gauge
Data Loggers for Measuring Vacuum
Vacuum data loggers for recording negative suction pressure or absolute pressure below atmospheric pressure. Log and store vacuum measurements for printing test reports or analysing process trends.
Calibration Equipment for Vacuum Range
Calibration pumps for generating vacuum pressures to check vacuum reading accuracy of sensors, gauges and switches with a master vacuum test gage.
LEX1 (Ei) High Accuracy Digital Pressure Gauge
DM01 Multi-Range High Accuracy Pressure Gauge
PGS40 Mid Pressure Calibration Hand Pump
Vacuum Measurement
Vacuum is the range of pressure which lies between absolute zero pressure and atmospheric pressure.
Vacuum pressures in the range of a few millibars up to atmospheric pressure are easily measured by diaphragm based pressure measurement instrumentation. In this range of partial vacuum pressures it is common to measure the vacuum using either a negative gauge reference or an absolute reference pressure sensing device. The choice of a negative gauge or an absolute reference will depend on whether you are interested in measuring the pressure compared to atmospheric pressure or to a perfect vacuum.
High vacuum pressures are very close to zero absolute pressure and much harder to measure with diaphragm type instrumentation. At high vacuum pressures it is necessary to use different sensor technology which is based on ionisation or thermal conductivity measurement principles.
Vacuum pressures are generated in many applications within the research and industrial sectors which include gas/vapour removal, leak testing, pick-up tools, sterilization, semiconductor processing and altitude simulation.
Help Guides
Articles with more information on vacuum measurement products & applications.
- What is the difference between vacuum and absolute pressure
- Measuring vacuum with negative gauge or absolute ranges
- What does negative and positive gauge pressure mean
- Suction Pressure
- Output signal orientation for a negative gauge pressure range
- Measuring negative pressure using a positive differential pressure range
- Can you have a minus 20 psi gauge vacuum measurement range
- Can you measure vacuum using a gauge pressure range
- Negative Gauge Pressure
Questions & Answers
0 bar absolute = -1 bar gauge
Is zero bar absolute the same as minus 1 bar gauge?
No, only when atmospheric pressure happens to correspond exactly to 1 bar absolute which rarely happens.
Does 1 bar cover the vacuum range
Is a minus 1 bar range adequate for measuring over the vacuum range?
For most applications yes, especially if measuring low suction pressures. If measuring a very high vacuum to some degree of accuracy, it is best to measure with a positive absolute range, since a negative gauge device will give different readings due to the changes in atmospheric pressure.
Technology used to measure over vacuum range
What type of sensing technology is used for measuring in the vacuum range?
For vacuum ranges 0-100 mbar up to 0-1000 mbar absolute it is usual to use a lower cost strain gauge diaphragm type. For ranges from 0-1 mbar up to 0-1000 mbar absolute, capacitive or inductive sensing techniques are the typical methods for measuring higher vacuums more precisely and with less drift. For ultra high vacuum ranges below 0-1 mbar it is not possible to measure this low a pressure with electromechanical devices and it is necessary to use less direct methods such as thermal conductivity and ionisation techniques.
Vacuum units
What pressure units are used for measuring vacuum pressures?
Vacuum level variations in a pumped chamber
Will the vacuum level be the same at the opposite end to the suction end of a chamber where a vacuum pump is connected?
If there is flow of gas, then you should expect there to be some difference in pressure, but it will depend on flow rate, size of volume and any restrictions between pump and end of chamber. If the suction pressure is static with no flow, then the vacuum pressure will equalise it all points.
Vacuum Gauge vs Vacuum Absolute
What is difference between reading pressure in vacuum gauge and vacuum absolute?
Vacuum gauge is measured from ambient air pressure in the negative direction. So for example at ambient air pressure the vacuum reading is 0 bar gauge and if a suction pressure of 0.25 bar is applied, the vacuum reading will be -0.25 bar gauge.
Vacuum absolute is measured from a perfect vacuum in the positive direction. At ambient air pressure the vacuum reading will be the barometric air pressure, let’s use 1.015 bar absolute as an example. If a suction pressure of 0.25 bar is applied the vacuum reading will be 0.765 bar absolute.