For most Canadian sites, the right H2S gas detector is a personal single-gas monitor worn in the breathing zone, with a fixed transmitter where the gas can build up unattended and detector tubes as a spot check. Hydrogen sulfide is colourless, flammable and toxic, and it can dull your sense of smell, so you cannot rely on the "rotten egg" odour to warn you. This guide sorts the H2S detectors ERE stocks by how they are used and where each one fits.
In this guide
- Why is H2S so dangerous to work around?
- Which personal H2S monitor should you choose?
- When do you need a multi-gas monitor instead?
- When is a fixed H2S detector the better answer?
- Can detector tubes measure H2S?
- How do you keep an H2S detector working?
- How do you choose an H2S detector, step by step?
- Frequently Asked Questions
Why Is H2S So Dangerous to Work Around?
Because it is toxic at low concentrations, it collects in low-lying and confined areas, and your nose stops being a reliable alarm. The CCOHS hydrogen sulfide profile describes a colourless gas with a rotten-egg odour that can dull the sense of smell, an extremely flammable gas, and a confined space hazard that can accumulate in hazardous amounts in low-lying areas. It lists the ACGIH exposure limits at 1 ppm (8-hour average) and 5 ppm (short-term), and adds that many Canadian jurisdictions have similar but not identical limits, so confirm the figure for your province.
That is why the instrument matters more than the procedure on paper. Typical places are wastewater lift stations, sewers, digesters, oil and gas sites, manure pits, pulp and paper, mining and any enclosed vessel that has held organic material. The entry rules for those spaces are covered in our confined space gas monitoring guide; the CCOHS confined spaces overview gives the general hazards. This article is about choosing the detector itself.
Which Personal H2S Monitor Should You Choose?
Choose between a maintenance-free disposable, a unit with a data logger, and a smaller watch-style monitor, based on how many people need one and whether you need exposure records. All three below are single-gas H2S instruments with diffusion sampling, so they read the air that reaches the sensor and need no pump.
| Monitor | H2S range | What sets it apart | Best for |
|---|---|---|---|
| Dräger Pac 6000 (DR-8326368) | 0 to 100 ppm, 0.1 ppm resolution | Disposable, up to two years of 24/7 operation with virtually no maintenance | Large crews, visitors, contractors |
| Dräger Pac 6500 (DR-8327613) | 0 to 100 ppm, 0.1 ppm resolution | Full data logger, STEL/TWA exposure alarms, replaceable battery | Safety programs that need exposure records |
| RKI GasWatch 3 for H2S (RK-73-0022-01) | 0 to 30 ppm in 0.1 ppm steps, 30 to 100 ppm in 1 ppm steps | 45 g, IP66/68, CR2450 battery rated up to 4,000 hours, wrist band or clip, ATEX, IECEx and CSA | Light wear, short-duration work |
The practical difference is who looks after the instrument. A disposable Pac 6000 is issued and replaced, which suits a crew you do not want to calibrate. The Pac 6500 and GasWatch 3 are maintained: they are bump tested and calibrated with 25 ppm H2S gas, and ERE lists the matching cylinder (NLB-F105325PN) and calibration adapter on the GasWatch 3 product page. Confirm alarm set points with ERE when you order, because they are configurable.
When Do You Need a Multi-Gas Monitor Instead?
Whenever the work is a confined space entry or the atmosphere can change in more than one way. H2S is flammable, and a space that holds H2S can also be short of oxygen or hold methane. A single-gas H2S unit tells you nothing about either.
The RKI GX-3R Pro monitors LEL, O2, H2S and CO plus one more infrared or toxic channel, has Bluetooth, and pairs with the SDM-3R Pro calibration station. Our portable gas detector buyer's guide compares the multi-gas options in full, and the portable gas detector collection lists every model.
When Is a Fixed H2S Detector the Better Answer?
When the hazard is the place and nobody is standing in it all day: wet wells, digesters, pump rooms and process areas. A fixed head keeps reading around the clock and can signal a controller, a horn or a plant alarm.
- The RKI explosion-proof tri-sensor head puts LEL (0 to 100%), O2 (0 to 25% vol) and H2S (0 to 100 ppm) in one housing, for indoor or outdoor wastewater use.
- The RKI digester gas monitor takes up to four sensors (CH4, CO2, O2 and H2S) and measures H2S up to 1,000 ppm, with 3,000 or 5,000 ppm optional, because digester gas holds methane, CO2 and high levels of H2S.
See the fixed gas detector guide and the fixed gas detector collection for controllers, transmitters and sensor options.
Can Detector Tubes Measure H2S?
Yes, as a spot check, not a warning device. The Sensidyne hydrogen sulfide tube (120SD, datasheet range 1 to 60 ppm) is used with a hand pump such as the AP-20S: you draw a measured volume of air through the tube and read the colour stain. It is useful to confirm an electronic reading, to sample a point you cannot reach, or as a backup. It does not alarm while someone is working. The gas detection tube guide and the tube and pump collection cover the rest.
How Do You Keep an H2S Detector Working?
Bump test it before use and calibrate it on schedule. A bump test only proves the sensor responds and the alarm sounds; calibration sets the reading against a known gas. The two are different jobs, explained in our bump test vs calibration guide. If you only need an H2S monitor for one project, our gas detector rental guide shows the alternative to buying.
How Do You Choose an H2S Detector, Step by Step?
- Name the hazard. H2S only, or H2S together with flammable gas and low oxygen.
- Decide person or place. Worn monitor for people, fixed head for an area.
- Pick the range. 0 to 100 ppm covers personal work; digester gas needs a higher range.
- Decide on records. If you need STEL/TWA exposure data, choose a data-logging model.
- Plan the maintenance. Disposable, or bump test and calibrate with 25 ppm H2S gas.
- Check approvals. Confirm the area classification and the certifications for your site.
- Add a backup. Keep tubes or a second instrument for verification.
Need help choosing an H2S detector?
ERE Inc. has been Canada's environmental equipment specialist for 30+ years. Tell us the site, the gases and the crew size and we will match the instrument.
→ Request a Quote | 1-888-287-EREC | Browse Gas Detectors | sales@ereinc.com
Frequently Asked Questions
What does an H2S gas detector do?
It measures hydrogen sulfide in the air with an electrochemical sensor and sounds an alarm when the reading passes a set point. The ERE personal monitors read 0 to 100 ppm.
Can I smell H2S before it is dangerous?
Not reliably. CCOHS notes that H2S has a rotten-egg odour but can dull the sense of smell, so a detector is needed.
What is the exposure limit for H2S in Canada?
CCOHS lists the ACGIH limits as 1 ppm (8-hour average) and 5 ppm (short-term), and notes that Canadian jurisdictions vary. Check your provincial regulation.
Single-gas or multi-gas H2S monitor?
Single-gas suits general work in an open area. Use a multi-gas monitor for confined space entry, where LEL, oxygen and CO matter too.
How often should an H2S detector be calibrated?
Follow the manufacturer's schedule and your site program, and bump test before each use. A disposable unit such as the Pac 6000 is built for maintenance-free service over its stated life.
Can I rent an H2S detector?
Yes. ERE rents gas detectors for short projects; contact us with the dates and the gases.
Related articles
- Portable Gas Detectors: A Buyer's Guide for Canada
- Confined Space Gas Monitoring Requirements in Canada
- Fixed Gas Detectors: A Buyer's Guide for Canada
- Gas Detection Tubes: A Buyer's Guide for Canada
Lire en français : Détecteur de H2S : guide d'achat (portatif, fixe et tubes) au Canada