A Layered Gas Detection Approach for Comprehensive Site Protection  

For safety managers and site emergency response managers, gas detection is a key focus.

• By Jason Winburn
• Dec 01, 2021

Many industries operate in hazardous environments, including oil and gas, mining, refineries, utilities, shipping, construction and others where exposure to harmful gases is common. Detecting gas leaks early is important because if left unresolved, those leaks can lead to injuries and property damage.

Flammable hydrocarbon gas leaks are invisible and often odorless, especially when operations take place outdoors. These gases can be toxic and highly combustible, so working with or around them can put workers in high-risk situations. If workers come in extensive contact with certain gas types and levels, they can suffer injuries affecting the eyes, lungs or central nervous system or sometimes even death. The statistics show that gas leak incidents are not as rare as they may seem. The U.S. Bureau of Labor Statistics shows that, for 2019, there were 642 fatal occupational injuries from exposure to harmful substances or environments and 99 fatalities from fires and explosions.

For safety managers and site emergency response managers, gas detection is a key focus which usually involves detection devices, monitoring software, PPE and extensive training and procedures. In situations involving hazardous gases, it is critical for facilities to respond quickly to any incident, from detecting gas leaks as they happen to making informed decisions and mitigating risks where possible. If these leaks are not detected, they could result in devastating fires or explosions, which can then escalate into litigation and fines.

Gas and flame detection solutions provide an early warning against these risks, but no single detection technology alone is 100 percent effective. This is where a layered approach comes in. By integrating the following layers of protection, employers can minimize the risk of flammable gas leaks going undetected and can be better informed to take steps to keep their workers protected.

What is a Layered Approach to Gas Leak Protection?

To enhance safety on a job site, site management should choose a comprehensive, layered gas detection system. The most effective way to deter, prevent and mitigate potential threats is to employ a layered safety approach in which independent yet interrelated layers of protection work together, offering comprehensive protection and providing confidence. The layered architecture of protection should be created according to the business structure, safety and production levels necessary for effective operations. Security controls should extend across the entire plant and business networks, enabling the facility to protect from potential incidents with an early indication of equipment that is not working properly and leaking harmful gases.

Often, detection systems are comprised of a combination of point detector technology, open-path technology, ultrasonic or acoustic gas detectors and flame detection. This layered approach to protection provides different methods of finding gas leaks that can help site management with its worksite safety plan.

In a mixed technology approach for gas and flame detection, each solution complements the effectiveness of the previous one, adding to the safety case. As each one acts independently, an unexpected issue will not affect more than one layer. For example, for fire and gas detection systems, gas detection and flame detection are two separate layers. If there is an issue with the gas detection layer and a fire ignites, flame detection comes into play. Simply put, more layers of gas leak detection provide more comprehensive protection. If all technologies outlined below are utilized, industries will benefit from a safer workplace.

Layer 1a: Point Infrared Gas Detection

Point infrared detection is often one of the most used options when it comes to flammable hydrocarbon gas monitoring. It can be deployed in large or small areas and confined spaces, especially near potential leak sources such as valves, flanges and pumps, offering a foundational layer of protection. A key advantage of deploying point detectors is that they measure actual gas concentrations at a point in space and time. By installing multiple devices, you can gain a more accurate map of gas release events.

These gas detectors provide continuous monitoring to detect gas clouds that could cause structural damage in case of an explosion. However, the gas must reach the detection point, which does not happen if the wind moves the gas cloud away from the detector or is dissipated before reaching the detector.

Layer 1b: Open Path Infrared Gas Detection

Open path infrared detection offers a different layer of protection against flammable gases that is less sensitive to wind speed and direction than point detection. Open path gas leak detectors play an important role in a facility’s fixed gas detection system, creating an invisible line that senses gases passing between the device’s transmitter and receiver.

Open path devices are available in short and mid-range applications from two to 120 meters (six to 393 feet), allowing workers to monitor specific areas or equipment. They are also available for long range perimeter or fence line monitoring from 60 to 330 meters (196 to 1083 feet), so that worksite employees can both monitor whether they are emitting harmful gases into neighboring areas or if neighboring plants have leaks of their own that need to be addressed. It also provides critical data on threat levels based on gas concentration and size, enabling plant operators to make informed decisions.

But even open path infrared gas detection is not a one-size-fits-all solution. Since flammable hydrocarbon gas from a leak must physically pass between the transmitter and receiver pair to activate an alarm, risk remains that gas leaks may go undetected if the line of sight is temporarily obstructed by a passing train or parked truck, underscoring the need for multiple gas detection solutions.

Layer 1c: Ultrasonic Gas Leak Technology

Detecting a gas leak early is key to preventing major disruptions to plant operations and preventing a catastrophic fire that could cause harm to workers. This is where ultrasonic gas detection technology comes in. The technology can ‘hear’ the ultrasounds emitted by escaping gas at the speed of sound, buying plant personnel critical time to respond. Even small and low-pressure leaks can be identified, eliminating challenges other gas detection systems face like changing wind directions or gas dilution in the open air.

However, ultrasonic detection alone is not enough. Only pressurized gas can cause an ultrasonic detector to activate, meaning non-pressurized leaks will never be heard. Also, interference from other ultrasonic noise sources present in the application can be louder than a small leak and can limit the detector’s listening range. Finally, ultrasonic gas leak detection will alert you to a leak but will not provide any indication of the gas type or concentration. For these reasons, a fully layered approach is needed for facilities to maximize their safety efforts.

Layer 2: Flame Detection

Flame detection is the final, critical layer of protection when working around flammable gases. If gas leaks go undetected and ignite into a fire, flame detectors can quickly identify the radiant energy produced by a fire’s flames and send out an alert, allowing personnel to intervene before small fires escalate into a disaster. There are different technologies to choose from, but either multi-spectrum triple infrared or ultraviolet plus dual infrared flame detection can detect fires caused by gas leaks from long distances with low levels of nuisance alarms.

The Technology Mix

Industrial applications and processes often involve the use of dangerous flammable, toxic and asphyxiating gases. Inevitably, these gases can escape, threatening those working within plants and those living nearby. Unfortunately, these gas releases may escalate, resulting in an environmental incident, explosions or even loss of life, in addition to serious reputational damage. The good news is that solutions are readily available to identify gas leaks early and help prevent those events from happening.

The use of multiple layers of detection significantly increases chances of identifying flammable gas leaks before they escalate into life threatening fires and explosions. Using a layered system that integrates a variety of gas and flame detection technologies enables optimal detection of flammable gas risks, and ultimately, safety managers can benefit from this early warning by taking actions for hazard mitigation, and most importantly for life protection of workers.

This article originally appeared in the November/December 2021 issue of Occupational Health & Safety.