Skip to content

Gas Detection and Monitoring in Confined Spaces

By: Barbara T. Nessinger, Chief Editor

Employees of industrial firms often find themselves, for a multitude of reasons, working in a confined space. Worker health and safety is critically important in these situations. To that end, the U.S. Occupational Health and Safety Administration (OSHA) has many regulations which focus on providing a safe working environment for workers who must work in these confined enclosures.

Having adequate gas-detection equipment is a big part of maintaining awareness and compliance regarding confined spaces. Gasses present a particular risk for workers with little maneuvering room, because they are often odorless and colorless. Therefore, without the proper detection tools, workers can be unknowingly exposed. Such hazards can be mitigated by sufficient personal gas-detection systems.

However, before acquiring solutions, companies should be fully informed on what is required and what is available to help meet the requirements and secure their employees’ safety.


According to OSHA’s definition, a confined space:

  • Has adequate size and configuration for employee entry;
  • Has limited means for access or egress; and
  • Is not designed for continuous employee  occupancy.

A few examples of confined spaces include underground vaults in the telecommunications industry, aeronautical fuel tanks, sewers, silos or coal mines, and other places where it is difficult for employees to enter and exit.

The term “permit-required confined space,” as defined by OSHA, is one that meets the definition of a confined space, above, and has one or more of the following characteristics:

  • Contains or has the potential to contain a hazardous atmosphere;
  • Contains a material that has the potential for engulfing the entrant;
  • Has an internal configuration that might cause an entrant to be trapped or asphyxiated by inwardly converging walls or by a floor that slopes downward and tapers to a smaller cross section; and/or
  • Contains any other recognized serious safety or health hazards.

Per OSHA’s rules, companies need to monitor enclosed spaces for gases before allowing workers to step into these areas. OSHA standards require that before an employee enters the space, internal atmosphere must be tested with a calibrated direct-reading instrument for the following conditions: oxygen content, flammable gases and vapors, and potential toxic air contaminants. Additionally, there may be no hazardous atmosphere within the space whenever any employee is inside. This standard is the impetus for using a multi-gas monitor to perform atmospheric testing, prior to entering a confined space.

Employers can install gas-detection machines to measure the level of air contaminants. Proper air monitoring is an OSHA requirement for permit-required confined spaces, because of the potential presence of atmospheric hazards.

Companies can use single-gas monitors or multi-gas monitors to ensure hazardous gases are not present in enclosed spaces, before workers enter. In fact, OSHA clearly dictates that employers perform continuous gas monitoring.


When choosing a monitor to test and continuously monitor a confined space, several attributes should be considered. The most important thing is to have a multi-gas monitor that is capable of monitoring for all OSHA-required hazards (oxygen, flammable gases and potential toxic air contaminants that may be present as a result of the processes that take place in or around the confined space). Next, consider a monitor that has either an internal or external pump that is capable of properly drawing the air sample back to a fresh air-monitoring point during initial testing of the space. The monitor also should have the capability of continuously monitoring the occupied space to ensure workers’ continued safety. Other equipment/accessories, such as sampling probes, durable carrying cases and rechargeable batteries, can be complementary and useful.

Most modern monitors are equipped with bright visual and loud audible alarms to warn of potential hazards. An internal datalogger helps employers comply with the documentation of the spaces’ hazards. A datalogger is a device containing a microprocessor; it stores information electronically taken from an instrument. The levels of all hazards being monitored can be downloaded from the datalogger to a computer or printed, for reference and record-keeping.

An automated instrument docking system is also extremely helpful when working with confined spaces. Such systems provide a myriad of benefits, including automated calibration/bump-testing (OSHA requires a “calibrated direct reading instrument” to safely detect a hazardous atmosphere); record-keeping; datalogging; and recharging. (Docking systems can be used to charge monitors when not in use. This ensures the monitor is fully charged for its next use). In addition, many automated maintenance systems include technology that helps diagnose potential problems/issues with the monitor.

Portable gas-monitoring systems may be designed for a single substance, or they can be fitted with multiple sensors. Some measure up to six gases and include piercingly audible, attention-getting, 360-degree visual alarms.

An alternative or addition to personal monitors is a transportable area monitor. Many have area monitoring, via diffusion or with a sampling pump; wireless communications capabilities; and a waterproof housing with continuous operation of approximately 60 hours. Extra run time helps increase productivity by minimizing new checks of the atmosphere for each shift change or when the space may be unattended. Portable gas monitors are lightweight and can be as small as a cellphone. They run on either rechargeable or replaceable batteries.

Another important aspect of managing confined space gas-monitoring programs is on-going maintenance. The best way to be certain a monitor is in peak shape is to utilize the services of a manufacturer’s factory service center. Using factory-trained service technicians ensures the monitor will be repaired or serviced by qualified individuals. Some of the key services to look for include in-house calibration and service; maintenance and warranty repair; and on-site mobile service/repair. Leasing or renting an instrument is also an attractive option, especially in cases of shutdowns or planned maintenance, where more instruments might be needed to perform the work within a specific timeframe.

WAY OF THE FUTURE The global market for gas detection systems has seen notable growth recently, something that Transparency Market Research (TMR) claims will continue into the 2020s. In a recent report, TMR said the worldwide gas-detection equipment market will grow at a compounded annual growth rate of 5.6% to $5.6 billion by 2024. In 2015, the market value was $3.4 billion. TMR cited the rising tide of rule-making and worker safety-focused regulations being enacted—not only in the U.S., but also in the developing world.

The shift toward natural gas is one more factor that is causing greater demand for gas-detection systems. Coal has seen significant declines in recent times (despite recent U.S. promises to “bring coal back”), and natural gas has risen to the top of many consumers’ preferences for heating and energy. The increased number of gaspowered installations multiplies the chances where workers might be in enclosed spaces— and increases the possibilities of gas leaks.

Persistence Market Research also found considerable opportunities for market expansion, given the high rate of infrastructure projects in the developing world. Researchers highlighted India and Brazil as countries undertaking particularly large projects that will elevate demand for gasdetection systems.

More companies than ever are investing in gasdetection systems. It’s important to choose the system that is right for a company’s needs to safeguard the health of all employees working in confined spaces.

Share on Socials!

Related Articles

Related Articles

Contact Lens Use in a Chemical Environment

Contact lenses are not eye protective devices, and wearing them does not reduce the requirement for eye and face protection.© terovesalainen – Guidelines to help ...
Read More

We Prevent Injuries and We Also Save Lives

Our hard hat Face Shield can be used in multiple industries. In any circumstance, you find yourself or your employees using a power tool that has ...
Read More

What is Digital Eyestrain & How to Prevent it

By Shelby Jenuwine, Contributing Writer Digital Eyestrain, also known as Computer Vision Syndrome, is a group of eye and vision-related complications that result from prolonged exposure ...
Read More

Follow WMHS!


Ind Hygiene


Scroll To Top