I am designing the ventilation system for a college of medicine and there are many laboratories, two of them are Radioisotope labs.
I am providing an exhaust system for each lab, consisting of two induced draft dilution fans (1 working + 1 stand-by).
Each exhaust system is serving 4 hoods inside one laboratory via a manifold, and provided with a carbon filter.
The radioisotope exhaust system is not connected to any other exhaust system (Fume or General).
The lab planner claims that it is mandatory to provide a separate exhaust system for each hood, with 1 fan only (no stand-by).
My questions are as follows:
Q1. Is it prohibited to manifold radioisotope hoods together?
Q2. Isn't providing a separate system for each hood (1 working + 0 stand-by fans) very risky (from hazard point of view, for the fan failure scenario)?