Magnehelic pressure gauge with scale from 0 to 0.5 inches of water (0 to 120 Pa), to indicate differential pressure


Return conditions : No returnable if used. For more information about our return policy, please refer to the "Orders and Returns" link on the home page

Magnehelic differential pressure gauge to swiftly indicate positive, negative or differential pressure. This tool comes with rubber tubing 3/16 in diameter X 10 ft length as well as mounting and sealing accessories. The display features a dual scale from 0 to 0.5 inches of water (inWC) and 0 to 120 Pascals. The pressure gauge can be used to measure the positive, negative and differential pressure with a high accuracy within 2% of full scale. Sold individually.

This pressure gauge is generally used on major sites of asbestos abatement and decontamination to avoid the spread of dust arising from asbestos or materials containing asbestos outside the premises. With such a tool, one can confirm that the work site is under negative pressure, thus ensuring that all dust will remain inside the contaminated premises until filtered.

The pressure gage should be installed outside the contaminated site near the employee entrance. Using a flexible tube, a gage reading will be taken inside the site and compared to the reading outside the site.


  • Designed to resist to shock, vibration, and over-pressures
  • Contains no liquid whatsoever which may freeze or evaporate
  • Requires no batteries or other sources of power
  • Used mainly in engineering and construction industries to measure fan and blower pressures, filter resistance, air velocity, etc.
  • Can easily be either flush mounted or mounted on the wall
  • Consist of a die cast aluminum case and bezel coated with a corrosion resistant acrylic cover
  • Pressure limits: -20 inHg g to 15 psig (-0.677 bar to 1,034 bar)
  • Relief plug opens when overpressure occurs at approximately 25 psig, 50,79 inHg, 1,72 bar
  • Temperature limits: 20°F to 140°F (-6.67°C to 60°C)
  • Designed for readings in vertical position
  • Equipped with 1/in diameter FNPT plug

Please note that we did get calls concerning the measurement scale in inches of water (in WC) rather than kPa (kilopascal). We have collected a few answers on that particular issue:
- Inches of water (inWC) unit of measurement is actually more precise than the kPa unit of pressure.
- No variation would be visible with a device graduated in kPa.

Operating principle during abatement and decontamination

  • Install black pieces with the help of the 3 screws provided in the kit which will subsequently allow a secure fit on plank.
  • Seal all remaining apertures at the back of the gage. We recommend a tight seal with Teflon tape.
  • Install the pressure gage on a plank and center it.
  • Set the gage to zero
  • Connect the rubber tubing to the - port.
  • Plug the port so that the gage takes the pressure inside the contaminated site from outside.
  • Start the negative pressure vacuum and see how the needle in the gage behave.
Type of productSafety equipment
Main categoryIndustrial accessoiries
Sub categoryAsbestos decontamination
Name of the productMagnehelic pressure gauge
Product codeSAHM
Length (in/cm)10 in / 25.4 cm
Width (in/cm)6 in / 15.24 cm
Height (in/cm)5 in / 12.7 cm
Weight (lb/kg)1.6 lb / 0.72 Kg
Return conditionsNo returnable if used. For more information about our return policy, please refer to the "Orders and Returns" link on the home page


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