The ability of a photoionisation detector (PID) to measure low levels of volatile organic compounds (VOCs) makes them a vital tool in the decision making process following a hazardous materials (HAZMAT) incident.
In the immediate aftermath of an accident, chemical spill or other incident involving hazardous materials there are many unknown factors. The speed at which these can be identified is key to the response, containment and clean-up effort. In the event that the HAZMAT materials are VOCs the sensitivity of photoionisation detection to measure low (parts per million – ppm) levels that can be toxic but not detectable by standard lower explosive limit (LEL) sensors make it a versatile tool for evaluating the dangers in an emergency response situation.
PID Theory Of Operation
PID instruments come in a number of models e.g. handheld, personal and fixed and may be used singly or in combination for monitoring fugitive VOCs in process industries such as oil & gas, petrochemicals and pharmaceuticals. However, they are also an extremely effective all-round device to the emergency services in a hazardous materials first response situation.
The Emergency Response Guidebook (ERG) produced by the United States Department of Transportation is used by emergency response personnel in Canada, Mexico and the United States when responding to a transportation emergency involving hazardous materials. The ERG provides vital information that helps emergency responders know how to act during an accident involving hazardous materials. It also provides vital information regarding fire extinguishment, first aid and evacuation distances.
or National Operational Guidance for the UK fire and rescue service:
In conclusion, one of the great benefits of PID instruments in a HAZMAT response situation is that whilst they are not always selective in terms of gas, they are small continuous monitors that provide an immediate response for anyone that uses them. PID instruments are ideal when the threat of a compound’s toxicity is greater than that of its risk of explosion and the accuracy and rate of response are of paramount importance. This makes them an invaluable tool in the First Responders resources from beginning to end.