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.