After a release in a chiller machine room the exhaust has been running for an hour and nobody at the door can smell anything unusual. What does that tell the crew about re-entering?
Correct Answer
D) That nothing has been established, because the decision has to rest on meter readings
These refrigerants have poor warning properties. R-11 and R-123 have a faint odor at best, and a person can be standing in an atmosphere well past the exposure limit or short of oxygen and notice nothing. There is no ventilation period that substitutes for measurement, because the amount released and the room's air change rate are both unknown. The crew enters when the oxygen and vapor monitors say the room is within limits, and not before.
Why This Is the Correct Answer
Warning properties describe whether a substance announces itself before it becomes dangerous, and these refrigerants have almost none. That is precisely why a machine room holding them carries fixed monitors. Re-entry after a release is a measurement decision: oxygen at or above the safe level, and refrigerant vapor below the exposure limit, both read on an instrument.
Why the Other Options Are Wrong
Option A: That the room is clear, because these refrigerants have a sharp odor at hazardous levels
The odor of these refrigerants is faint and easy to miss, and people stop noticing it quickly. It gives no useful warning of a hazardous concentration.
Option B: That the room is clear, because an hour of exhaust exceeds the required ventilation period
No fixed ventilation period clears a room, because neither the size of the release nor the room's actual air change rate is known.
Option C: That the room is probably clear, so entry with a cartridge respirator is now reasonable
A cartridge respirator filters contaminants but supplies no oxygen, so it is the wrong protection for a room that may still be oxygen short.
Memory Technique
Your nose is not a monitor. It has no alarm and no calibration date.
Reference Hint
Low-pressure refrigerants have poor warning properties; re-entry after a release is decided by oxygen and vapor monitor readings.
More epa-608-type-3 Questions
Some jobs on a chiller count as a major repair under the refrigerant rules, which changes what a technician is allowed to do with a badly leaking machine. Which job falls into that category?
An owner asks how many pounds of refrigerant the rules allow to be left inside a chiller once the recovery has been signed off. What is the correct answer to give him?
The motor of a hermetic centrifugal chiller sits inside the pressure boundary rather than outside it on a shaft. What follows from that construction?
An oxygen monitor is used to decide whether a chiller machine room is safe to enter after a refrigerant release. Below what oxygen reading is the atmosphere treated as oxygen deficient?
A low-pressure chiller's rupture disc has a discharge line running from it. Where does that line have to terminate?
A refrigerant vapor detector in a chiller machine room reaches its alarm level. Besides sounding, what is that alarm expected to do?
Which piece of equipment requires a technician to hold Type III certification before it may be serviced?
What property of the refrigerant is what actually places an appliance into the low-pressure category?
During normal operation, what condition exists inside the evaporator of a running low-pressure centrifugal chiller?
In what unit is the required final recovery vacuum for a low-pressure appliance normally expressed?
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