During recent conversations with several forensic scientists the topic of safety equipment has been re-occurring. These scientists have the responsibility of managing the design process and other aspects of the forensic laboratory after its construction.

Several questions were asked concerning Environmental, Health & Safety (EHS) issues. In this column we will address some of the most common EHS questions that arise during the design process.

1) Does the emergency shower/eye wash combination unit require a floor drain?
a. Yes. Local codes may require a floor drain at ES/EW units.
b. No. Eventually the trap will dry out and sewer gases enter the building.
c. Yes. Client insists on a floor drain due to safety issues.
d. No. It is costs more for floor drain primers, sloped floors and a waste water holding tank.

2) Should we ventilate the acid and flammable storage base cabinets?
a. No. It may draw fire into the cabinet.
b. Yes. To remove odor from the cabinet before opening.
c. No. The cabinet has not been UL labeled.

3) Which fire suppression system is best for the evidence vault?
a. Wet pipe
b. Pre action
c. FM 200

4) Where is the best place to mount the fire extinguisher in the lab?
a. Near the exit door
b. On the fume hood
c. On the exit path in the lab

Floor Drain
Yes it is true. Some local plumbing codes will require a floor drain with each emergency shower and eye wash station. Some combination units provide a bowl or pan to collect eye wash water that can be plumbed to a drain. It is not necessary to slope the floor to the drain; just provide a dished area around the drain to help in collecting the water. These floor drains do have a tendency to dry out when not used on a regular basis. One secret to keeping the trap wet is to pour in some vegetable oil. The oil evaporates at a much slower rate preventing sewer gas from entering the facility.

Even though floor drains may not be required, your EHS officer may ask for it as a safety feature. Working with your plumber and architect to find the appropriate solution is very important. A second device can be installed to prevent the trap from drying out. A trap primer valve is a precision device designed to deliver potable water to a seldom used floor drain. If it detects a pressure drop of 5 to 10 P.S.I.G., the valve is activated. The Trap Primer is fed with fresh, cold water. Also a waste water holding tank may or may not be required per local plumbing codes.

Acid and Flammable Storage Cabinets
Acid and flammable storage cabinets should meet OSHA, NFPA, and UFC requirements. Also these cabinets should be UL labeled. However, it has been my experience that when these cabinets are fire tested, they aren’t ventilated; the cabinet doors are closed and the cap is on the flame arrestor vent. Each manufacturer is slightly different and inquiries must be made about the fire tests preformed to determine if it had been tested with a vent connection or not. Making a hard vent connection may make your insurance coverage null and void.

Industrial Hygienists would prefer that these cabinets were ventilated for one reason: a non-ventilated cabinet allows for the buildup of odor within the cabinet when the lab occupant opens the cabinet, pulling the door toward him or her; the odor rolls out and into the breathing space on the lab occupant. Having the cabinet ventilated means the cabinet is under a negative pressure, preventing the escape of odor into occupied space.

Some fume hood vendors do offer a vent connection from the storage cabinets under the fume hood up into the fume hood work area behind the baffles. However, some local codes prohibit this due to the notion that if a fire were to occur it would probably be in the fume hood and the vent exhaust would just feed the fire. Again, check all the codes and labels on the cabinets.

Fire Suppression Systems
The proper storage of evidence is a serious matter, particularly during a security breach or a fire. Wet pipe systems are the most common fire sprinkler system. A wet pipe system is one in which water is constantly maintained within the sprinkler piping. For a sprinkler head to become activated, heat from the fire must reach a temperature of 135 degrees or more to break the glass bulb that signals the water to flow and put out the fire.

A pre-action fire sprinkler system is a dry pipe system, meaning that water is not normally contained within the pipes. Water is held from piping by an electronically operated valve, known as a pre-action valve. Valve operation is controlled by independent flame, heat, or smoke detection. Water is not released until two types of detection have been made.

Finally, the FM-200 system or HFC-227, chemically known as heptafluoropropane, is an alternative fire suppression system that has replaced the ozone depleting Halon 1301 that was used extensively before 1994. FM-200 has no ozone deleting potential. It has been found by leading toxicologists to be safe for the environment and people. People and evidence can be exposed to normal extinguishing concentrations without any fear of health problems or damage.

Fire Extinguisher Location
Before deciding the best place and type of fire extinguisher for your lab, check with your insurance policy. Some insurance policies allow lab occupants to extinguish a small fire such as a computer, fume hood, or bench fire. However, some policies stipulate that the lab occupant use the fire extinguisher as a tool to vacate the premises immediately. If your situation allows you to attempt to extinguish the fire, then providing a small hand-held CO2-type (works on B and C fires) or dry chemical BC or ABC extinguisher on the side of the fume hood may be the right answer for your facility. The only reason to locate the fire extinguisher on or near the fume hood is because there is a higher chance for fire to begin in the fume hood.

A second and larger extinguisher should be mounted in the lab to aid with the fire and provide protection for exiting the lab/building. If you are interested in learning more about the use of a fire extinguisher, you may choose to visit the following site:

These Environmental Health & Safety issues arise every day during the design process of a forensic facility. It is important to make your wishes known to the design team and to work collaboratively for a solution. I hope these answers will help you and your design team, in resolving issues during your design process.

Ken Mohr is a principal of HERA, Inc., laboratory consulting partner firm in Crime Lab Design. With 17 years of experience with technically demanding projects, Ken specializes in forensic laboratory planning and design. He has successfully completed needs assessments and new/renovation design of numerouscrime labs.