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Observator DIFF

Available for hire

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Developed by Observator Instrument B.V. for the automatic measurement of air volume from supply and extract terminals, this instrument has a built in fan and pressure compensation facility that ensures minimum errors during use.

Designed to be self-adjusting for supply and extract systems, the instrument automatically detects the direction of flow allowing the 250mm square aperture to be placed securely over the grille. The adjustable display arms not only allows flexible operation it enables the system to be read from almost any angle.

Product Features

  • Range of accessories
  • Calibration options
  • Document downloads
  • Instrument video

Instrument product options

1. Select a model (1 available)

Continue to select accessories

2. Select accessories (5 available)

3. Select a calibration (2 available)

4. Request a quote



Standard supply comprises of:-

  • Instrument
  • AT-242 solid hood designed specifically for domestic ventilation systems
  • Carry case
  • Batteries and charger
  • Calibration certificate
  • PC software (DIFFiner) and 2GB SD card for the fast storage of data
  • Manual



  • Fabric hoods 400 x 400mm, 600 x 600mm, 310 x 1234mm and 310 x 1534mm
  • Fast charger


Measuring range 10 to 400m3/hr, -15 to +70°C and 0 to +95% non condensing relative humidity

Measuring aperture size 250mm x 250mm

Accuracy ±3% of reading ±1m3/h.



NHBC ventilation guidance note January 2014

  • Technical Document
  • PDF file
  • 659 KB

Observator Diff data sheet

  • Technical Document
  • PDF file
  • 1 MB

Observator Diff user manual

  • Technical Document
  • PDF file
  • 991 KB

Observator DIFFiner software data sheet

  • Technical Document
  • PDF file
  • 930 KB

Demonstration video

Observator Diff and software product overview
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