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Hydrogen Sulfide (H2S) Gas Detectors

Hydrogen sulfide (H2S) can be found in many industries and applications, including iron-smelting facilities, landfills, food processing plants, and breweries. Nuclear power plants use hydrogen sulfide to produce heavy water—an alternative to regular water that enables reactors to use ordinary uranium instead of enriched uranium. Farmers use hydrogen sulfide as an agricultural disinfectant. Hydrogen sulfide is highly flammable, explosive, and extremely toxic.

Discover our range of hydrogen sulfide monitors especially designed to detect H2S in any facility. Let Industrial Scientific experts help plan the right Hydrogen Sulfide monitoring solution

hydrogen sulfide detector (H2S monitor) clipped on the collar of an industrial worker

Characteristics of Hydrogen Sulfide

Hydrogen sulfide is a colorless gas that is known by its characteristic rotten egg odor. It appears naturally as a byproduct of decomposition. One of the drawbacks to trusting your sense of smell for protection against hydrogen sulfide is that prolonged exposure to the gas renders the sense of smell inoperative.

Hydrogen sulfide is a highly toxic gas. It reacts with the enzymes in the bloodstream to inhibit cell respiration. In other words, high concentrations of hydrogen sulfide can shut off the lungs. Low concentration exposure to the gas can burn the respiratory tract and cause swelling around the eyes.

More about Hydrogen Sulfide expand table collapse table


Will explode; LEL 4.0%
Extremely toxic, Oxidizing agent
Hydrosulfuric acid, sewer gas, sour gas, rotten egg smell
Exposure limits:
PEL\TWA: 20 ppm
STEL: 5 ppm / 15 min.
IDLH: 100 ppm / 30 min
Oil and Gas industries (complete from drilling to refining), pulp and paper, and wastewater treatment

Effects of Various H2S Levels

H2S Level in PPM
Resulting Conditions on Humans
Minimal perceptible odor.
Easily detected, moderate odor.
Beginning eye irritation.
Strong, unpleasant odor, but not intolerable.
Coughing, eye irritation, loss of sense of smell after 2 to 5 minutes
Marked conjunctivitis (eye inflammation) and respiratory tract irritation after one hour of exposure.
Loss of consciousness, cessation (stopping or pausing) of respiration, and death.
Unconsciousness at once, with early cessation of respiration and death in a few minutes. Death may occur even if the individual is removed to fresh air at once.

How to Detect Hydrogen Sulfide Using an H2S Monitor

To accurately monitor the many areas in which this gas can pose a hazard, make use of one of Industrial Scientific’s many H2S monitors. Options include the Ventis® Pro5, Ventis® MX4, MX6 iBrid®, and Tango® TX2 multi-gas monitors, the Tango® TX1 and GasBadge® Pro single-gas monitors, and the Radius® BZ1 Area Monitor.

Area Monitor

Radius BZ1

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Multi-Gas Monitor

Ventis Pro5

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Multi-Gas Monitor

MX6 iBrid

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Single-Gas Monitor

GasBadge Pro

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Multi-Gas Monitor

Ventis MX4

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Single-Gas Monitor

Tango TX1

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Multi-Gas Monitor

Tango TX2

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Frequently Asked Questions

What does a hydrogen sulfide detector (H2S monitor) do?

Hydrogen sulfide detectors, also known as H2S monitors, detect hydrogen sulfide, a highly toxic gas present in oil and gas refineries, sewer systems, and other industrial settings. These H2S monitors use sensors that are sensitive to the gas and can detect even low levels of hydrogen sulfide. Once the concentration of hydrogen sulfide reaches a certain level, the H2S monitor will sound an alarm, warning people in the area that the gas is present. H2S monitors are essential safety devices that can help prevent accidents and save lives in high-risk workplaces like the oil and gas industry, wastewater treatment plants, and other industrial environments.

What level of hydrogen sulfide causes an H2S monitor to alarm?

The Occupational Safety and Health Administration (OSHA) has established a permissible exposure limit (PEL) for hydrogen sulfide of 10 parts per million (ppm) over an 8-hour workday. H2S monitors are designed to sound an alarm when the concentration of hydrogen sulfide exceeds the OSHA PEL. However, some monitors may be set to alarm at lower levels, depending on the specific requirements of the workplace or industry. It is important to note that even low concentrations of hydrogen sulfide can pose a significant danger, causing symptoms like eye irritation, headache, and nausea. Therefore, it's crucial to follow proper safety procedures and wear personal protective equipment when working in environments where hydrogen sulfide may be present.

What is the normal range for a hydrogen sulfide detector?

While the normal detection range for hydrogen sulfide monitors, or H2S monitors, can vary depending on the specific device and its settings, most have a range of 0 to 100 parts per million (ppm) or higher. However, it is important to note that the concentration of hydrogen sulfide considered safe can differ based on how long a person is exposed. For instance, the Occupational Safety and Health Administration (OSHA) has set a permissible exposure limit (PEL) for hydrogen sulfide of 10 ppm over an 8-hour workday. Nonetheless, exposure to higher concentrations of hydrogen sulfide for shorter periods can also be hazardous.

For your safety, it's crucial to select an appropriate H2S monitor for your specific workplace and industry and ensure that it is accurately calibrated to detect hydrogen sulfide at required concentration levels.

Where should H2S monitors be worn?

This is a commonly misunderstood rule—many workers might respond to this question with hard hat, collar, belt, or shoe. The confusion likely comes from the false notion of the “detection range.” A detection range is described as the distance from which a personal gas monitor can detect gas. The reality, however, is that gases need to come in direct contact with an instrument’s sensors to detect them.

Hydrogen sulfide detectors should be worn in a worker’s breathing zone, which OSHA defines as a radius of approximately six to nine inches around a worker’s shoulders. A collar, lapel, or breast pocket usually meets those criteria. This location also keeps the instrument visible so you can see any alerts if your hearing is impaired while working in a high-noise environment.

Even though H2S is heavier than air, you should not wear H2S monitors lower on your body because you risk damaging the detector or not hearing the alarm. Always wear your hydrogen sulfide detector in the breathing zone.