Page 11 - Occupational Health & Safety, December 2017

GAS DETECTION
Portable Gas Detection
Safety should always be of the highest priority—it is the reason these detectors were invented, after all. There are several essential features to consider when selecting one.
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This Q&A with Larry Medina, product portfolio mar- keting manager for portable gas detection devices in North America at Draeger, Inc., discusses key features and how to identify the “right” device for your own circumstances.
1. What should safety managers look for in a por- table gas detector?
When it comes to portable gas detection, device adaptability is key. Since hazardous gases can present themselves in a myriad of environments—spanning industries such as oil and gas, wastewater treatment, pharma, and chemical and fire services—portable gas detectors need to be able to identify a variety of threats. By performing a Process Hazard Analysis (PHA), safety managers can identify and comprehend potential risks present at a given work site.1 Because each work site presents a unique set of challenges, companies can leverage the PHA to preemptively plan for and introduce necessary steps to mitigate risk and danger for onsite workers. Broadly speaking, PHAs will identify gas-based risks that fall into three catego- ries—potential for explosion, oxygen enrichment or oxygen deficiency , and toxic gas poisoning.
In work sites where there is a potential for explo- sion, such as mines, refineries, and chemical plants, flammable gases and vapors are typical ingredients for ignition. If the ratio of a flammable gas to oxygen (or air) lies within a certain Lower Explosion Limit (LEL), an ignitable mixture can form. The LEL of almost all known flammable gases and vapors lies roughly be- tween 0.5 to 15 Vol.-%, however, it’s crucial for safety managers to understand the specific potential hazard- ous materials that can arise on site and ensure that their suite of gas detection equipment can effectively alert workers in such an event.
The second category pertains to oxygen enrich- ment and oxygen deficiency. To begin with the for- mer, the heightening of the atmospheric oxygen con- centration can profoundly impact flammability and even cause materials to self-ignite. Oxygen deficiency, on the other hand, is often caused by the release of an inert gas. Typically, oxygen deficiency becomes haz- ardous in stages. If the air’s oxygen concentration dips below 17 Vol.-%, workers may be in an early stage of danger. If the air’s oxygen concentration drops even further—between 11 and 14 Vol.-%, for example— workers may experience unnoticeable decreases in physical and mental performance. If the oxygen con- centration dives again—below 11 Vol.-%—workers
can lose consciousness.2
Like oxygen deficiency, risk of poisoning via the
toxic gases themselves can impact work sites that perform industrial processing. Notably, authorized commissions in several countries define the concen- trations at which these gases are considered danger- ous. In certain regions, gases are deemed “very toxic” if their LC50 is less than 0.5 g/m3. Fluorine, hydrogen cyanide, and sulfur tetrafluoride are examples of gases that can fall under this designation.3 Companies and safety managers that complete a PHA can determine what capabilities they need in a portable detector and make the next step in identifying the “right” device.
2. Given the breadth of their capabilities, what are some “must-have” features of portable gas detectors? There are several essential features that can be important to consider when selecting a portable gas detector. First, it can be important to assess a portable gas detector’s durability. Sturdy, resilient detectors will likely last longer than their weaker counterparts, and detectors with shock-proof, chemical-resistant, and rubber-based coatings tend to have longer lifespans. The same can be said for detectors that meet the re- quirements of IP68 (an indication of high resistance
to water and dust ingress).
Ease of use can be another important feature
to consider when selecting a portable gas detector. During an emergency, a device that is simple to operate and read can help speed up the appropri- ate response. For example, a detector that features multi-toned audio signals, a vibrating top and bot- tom, and bright, flashing, 360-degree LED visual signals can help prevent missed alarm signals. If drilling or other loud procedures were to obscure the detector’s audio alarm, for instance, workers
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