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RepWars Briefing - Questions & Answers
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Question...
"In a school with a science lab.... The School will have a RPBFP at the point of entry (because of the lab)....
The Lab Sinks will have Vacuum Breakers and protection is required at any other equipment, i.e., fume hoods, etc.
Do you think an RPBFP device would also be required at the point of entry to the lab itself? And what about an emergency eye wash in the lab, should it come from
the potable water source in the corridor or would the water system in the lab be safe for the eye wash? We are starting to see more of the eye washes on a hose
which could be laid in a lab sink. We had a long discussion about all this at the (City Plumbing Inspection) office this morning. I'm curious about your opinion about this.
"
RepWars Reply...
RECOMMENDATIONS:
- Additional backflow prevention should not be required at the point of entry to the lab itself.
- The potable water system within the lab can also supply service to the eyewashes.
- A vacuum breaker should be installed in the service to each hose type eyewash unit.
EXPLANATIONS:
- The reduced pressure backflow prevention assembly in the main service to the facility protects the municipal system. Even though all fixtures and equipment requiring plumbing services within a facility will be provided with individual cross-connection control, some Authorities also require a main service BFP due to the fact that they have no assurance of controlling future modifications an Owner may make to an approved installation. There is no way of determining where an Owner will introduce a cross-connection within a system. Therefore, the benefit of mandating redundant devices can not be realistically known. An Authority shows "due diligence" by requiring separation between a suspected contamination source and a municipal system. An Authority begins to pose economic burdens when it attempts to control all possible hazards.
- If a water system within a lab is considered "potable", then it can safely provide flushing for the eye. Eyewash units complying with ANSI Z358.1 will prevent suspended solids or excessive velocity from damaging the eye.
- Compliant eyewash units are provided with stay-open valves. A hand-held hose type unit can inadvertently be placed within a sink containing stored liquid. This produces a cross-connection scenario requiring a vacuum breaker. Most eyewash unit manufacturers offer an optional vacuum breaker device that can be specified with the unit.
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