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Forensic facilities present a wide range of fire prevention and protection challenges because of the services they provide and the support spaces inside the facility. The storage of evidence and reference material, protection of scientific equipment, handling and storing flammable chemicals within the laboratories, and providing safe egress for the building occupants are among the vital fire issues that must be considered

Every forensic facility should have a comprehensive fire prevention and protection plan. This plan is designed to protect the building occupants, preserve equipment and property, and assist emergency response teams. In addition to the plan, providing proper fire safety involves good laboratory practices, appropriately designed storage facilities, adequate first response devices, smart ventilation control strategies, and efficient emergency response plans. All of these pieces must be in place for an effective prevention and protection program to exist and respond when needed.

In this article, we will examine the unique forensic fire challenges within various spaces and the operating systems that should be in place.

Spaces
The department for controlled substances is the largest user of flammable chemicals. Good laboratory practice within this area requires an adequate number of chemical fume hoods for staff with flammable storage cabinets located at or in close proximity to fume hoods where these chemicals are being used. If this laboratory will be dealing with clan lab materials, the lab should be located adjacent to the building exterior so that large quantities of chemicals are not brought deep into the facility.

Latent print processing and collection presents a few fire concerns. One area that requires special attention is the use of ninhydrin (a skin, eye, and respiratory irritant). Ninhydrin is very flammable when vaporized. Any activities where it is involved should be conducted in a super glue cabinet designed to handle the vapor and exhaust it when processing of the evidence is complete. DFO and Petroleum Ether must be used in a fume hood because both have a very low flash point and are considered highly flammable without an effectively ventilated device. Another common chemical used to develop latent prints is silver nitrate, which is an oxidizing agent that should not be stored in the same cabinet as flammable agents.

A large instrument room may house many pieces of major scientific equipment valued at millions of dollars. The challenge is two-fold:

  • Prevent accidental discharge of water from the suppression system
  • Suppress a fire if one does occur

Evidence and property storage areas vary from small closets to large warehousing facilities. Each individual facility presents different fire prevention and protection challenges. The most fundamental step when developing your fire protection and prevention plan is to decide what size investment is prudent to preserve evidence from water damage.

Property storage areas are often large warehousing operations that house a wide variety of materials on racks and shelving systems. These spaces are faced with different suppression challenges and may require higher density sprinklers and in-rack sprinkler systems. Since the volume of these spaces is so large, the use of chemical or gaseous suppression systems is generally not feasible.

Alone, vehicle exam bays do not present distinct fire protection challenges unless a pit is used for under vehicle access. De-fueling vehicles and inspecting them for explosives or other flammable cargo is clearly a significant part of the investigatory process. Protocols like these have the greatest impact on fire prevention. There are limited amounts of explosive materials inherent in firearms examination and testing. The location of sprinklers in the firing range must be sufficiently detailed to prevent damage from a stray bullet.

 

Systems
A wet sprinkler system involves overhead sprinkler piping; usually concealed above the ceiling. The system is filled with pressurized water (including an anti-freezing agent if necessary) and the piping is connected to sprinkler heads that penetrate through the ceiling. Each sprinkler head uses fusible links that melt under excessive heat allowing water to flow. This system meets basic code requirements and is the lowest first cost solution. In the event of a fire, this system will activate only in the affected area.

Interlocked dry pipe systems use water as the extinguishing agent. One of two things must happen before water is discharged:

  • A temperature rise in the space that melts the fusible link on the sprinkler head
  • The electronic detection of fire or smoke in the space which in turn opens a valve upstream of the sprinkler head letting water flow into the system

Using an interlocked dry pipe system greatly reduces the possibility of accidental discharge of water because things like physical damage to a sprinkler head causing water discharge are now eliminated. An interlocked system has a moderate first cost premium over a wet pipe system.

Both CO2 and FM200 are examples of chemical or gaseous
system types which use an electronic method of fire or smoke detection to release the extinguishing agent. These systems have the advantage of responding quickly and can catch a developing fire early in its existence. There is normally limited clean-up required from their discharge and the equipment is left unharmed.

There are hazards associated with CO2 systems since they displace oxygen from the room and present a suffocation hazard to personnel. Given that these systems commonly use extinguishing materials that are of limited quantity, a “double shot” or backup capacity needs to be considered. In some cases, code officials have also insisted on providing a wet system as backup (to maintain the “fully sprinklered building” designation), defeating the main purpose of installing a chemical or gaseous suppression system. Gaseous and chemical fire suppression systems are the most expensive fire suppression option.

Flammable storage cabinets are constructed of 18-gauge steel. Sides, top, bottom, and doors are double-walled with a 1 1/2” air space between walls. Vents, with 2” threaded fittings, have fire baffle and cap. Flammable Cabinets must be clearly labeled with a sign that reads: “Flammable — Keep Fire Away.” They must also include a grounding attachment; 3-point key lock; 2” raised, leak proof door sill; and adjustable shelf with supporting brackets. Each cabinet can support up to 350 pounds of flammable material.

Venting of flammable storage cabinets is not recommended due to the fact that it could reduce the fire protection effectiveness of the cabinet and void the Factory Mutual, Underwriter's Laboratory, or other qualified testing agency labels. A flammable storage cabinet should not be located near the exit because it would compromise the safe evacuation of the occupants if a fire did occur.

Fires that occur in lab environments often involve hazardous chemicals and the smoke, fumes, and vapors they generate can present an obstacle to responding emergency response team. To alleviate this condition laboratory exhaust systems need to remain in operation to remove toxic products of combustion. This differs from office type ventilation systems that are configured to shut down in the event of a fire.

Today the most widely used fire extinguisher is a multipurpose dry chemical type, designed to effectively handle Class A, B, or C fires. The extinguisher should be placed near the potential source and located to assist the user to exit the space. Fire definitions are: Class A – paper, trash, plastic; Class B –flammable liquid and gases; and Class C – energized electrical equipment.

When experiencing a fire, first activate the building’s alarm system and call the emergency response team. Your next step is to assess the safest path to exit and direct the building occupants in that direction. If you have been properly trained to do so, attempt to extinguish the fire. The correct operation of an extinguisher is to pull the pin out, point the hose at the base of the fire, and sweep the discharged product back and forth until distinguished. A great resource for additional information is the National Fire Protection Association standards 10 and 12.

Conclusion
Choosing the right fire prevention and protection plan for your forensic facility requires serious consideration of all options. It is important to remember that one system type may not meet all of your facility’s needs. Consider all of the facility’s fire prevention and protection issues and then determine your correct solution.

Lou Hartman, P.E., is a Principal and Sr. Mechanical Engineer with Harley Ellis Devereaux, and Ken Mohr is a Principal and Sr. Forensic Laboratory Planner with HERA, Inc. HED and HERA together form a strategic alliance called Crime Lab Design, which provides full A/E services for forensic and medical examiner facilities. For more info, please visit www.crimelabdesign.com.

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