OHS Canada Magazine

Protection with Detection

June 6, 2019
By Jeff Cottrill

Of all the physical hazards that can threaten work­ers, one of the most subtle and most difficult to detect and prevent is hazardous gases — many of which are invisible or odourless, like carbon monoxide (CO). For people who work in confined spaces and other environments that may have unknown gases, gas-detection devices are a must.

Gas-detectors, also known as gas monitors or in­strumentation devices, contain sensors that can monitor the presence of different types of gases. A device may contain only one sensor for a workspace with only one specific type of gas hazard, or it may contain multiple sensors if more than one type of gas may be around. The four most common gases that these devices are built to detect are CO, oxygen, hydrogen sulfide and gases with lower explosive limits.

While portable gas detectors are commonly used in con­fined spaces, these devices are also essential to refinery em­ployees, those who work with hazardous chemicals or attend traffic accidents, train derailments and fuel spills, oil and gas workers and miners, as well as employees in power genera­tion, fire services, emergency response and the military.

 Gas monitors can come in portable or fixed formats. Por­table monitors can be carried around by a mobile worker, while the latter can be mounted on the wall. “Portable gas detection is going to be your single-gas and multi-gas detectors,” says Jason A. Fox, a segment market manager who focuses on portable monitors with MSA in Cranberry Township, Pennsylvania.

Because monitors have different kinds of sensors for dif­ferent gases, an employer must conduct a risk assessment to determine the specific gases that workers might come across before deciding what kind to purchase. Job applications have to be considered, as well as which par­ticular hazards are associated with which applications, to get the right sensors.

Beyond that, users might also want to look at whether there are any other particular functions they would like the gas detec­tor to perform. Some devices have a simple design for personal protection only, while others have added capabilities, like a wireless function or a built-in radio. These are most useful when a worker needs to be remotely supervised while in a confined space.

It may be tempting for an employer to save money with a cheaper product, but price variance in gas detectors normal­ly depends on the number of gases they detect, according to Jeremy Majors, a service manager with Gas Clip Technolo­gies in Cedar Hill, Texas.

“A lot of it has to do with the sensors and the way that it is manufactured,” Majors says. A standard four-gas moni­tor may range in price from US$600 to $1,000, depending on the brand. “When you jump to the five-gas monitor, that will jump the price upwards of, say, $1,500 or so,” he adds.

More important than the price is the total cost of owner­ship, which many employers overlook. For example, many do not factor in how much it costs to maintain a gas detector over its life. Those costs include sensor replacements and gas consumption for bump tests. Other crucial factors to consider are how fast the device detects and measures the gas, or the actual response time of the sensors that are chosen, and whether the product meets the current CSA Group standard.

If a gas detector is not working properly, the worker will not know until it is too late. So a device needs to undergo a “bump test” before every use. Although bump tests are necessary, they tend to reduce the lifespan of many gas monitors.

For example, with some manufacturers, their sensors are actually ‘consuming sensors’ — the more gas they see, the less life that they actually have.” As such, it is critical for a user to choose the correct concentration of gas for the bump check.

Gas detectors also have to undergo calibra­tion regularly to make sure that they perform accurately. While it can be helpful to get a de­tector that requires minimal calibra­tion, it never hurts to double-check once in a while.

 This article was first published in the May/June 2017 issue of OHS Canada.