Gastec 4HM Gas Detector Hydrogen Sulphide Tube

Gastec 4HM Gas Detector Hydrogen Sulphide Tube is a gas detector which performing measurements using a gas sampling pump.

Gastec 4HM Gas Detector Feature

  • On-site measurements can be performed easily by anybody, anytime and anywhere, in a short time
  • Easy-to-check direct reading possible due to the calibrated scale directly printed on the tube
  • An extensive measuring range can be obtained by adjusting the sampling volume
  • In order to assure high precision, each production lot is tested and calibrated independently, Each detector tube has its own quality control number printed on the tube
  • Long shelf-life with excellent long-term stability


Measuring range 25 to 50 ppm 50 to 800 ppm 800 to 1600 ppm
Number of pump strokes 2(200 ml) 1(100 ml) 1/2(50 ml)
Correction factor 1/2 1 2
Sampling time 1.5 min 45 sec 30 sec
  • Detecting limit: 5 ppm (2 pump strokes)
  • Color change: White → Brown
  • Corrections for temperature & humidity: Unnecessary
  • Relative standard deviation: 5 %(for 50 to 800 ppm)
  • Shelf life : 3 years

Another Article:

Gastec 4HM Gas Detector Reaction principle

  • H2S + Pb(CH3COO)2 → PbS + 2CH3COOH

Possible coexisting substances and their interferences

Substance Concentration Interference Changes colour by itself to
Nitrogen dioxide  ≧ 1/4  - No
Sulphur dioxide ≧ 1/1 No
Ammonia No No
Carbon dioxide No No
Carbon monoxide No No
Mercaptans No No
Organic gases & vapours No No
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