Where does refrigerant vapor collect if a chiller releases a large part of its charge inside a machine room?
Correct Answer
A) Low along the floor and down in pits and trenches, because the vapor is heavier than air
Refrigerant vapor is substantially heavier than air, so it sinks and collects in the lowest parts of a space. Floor level, sumps, pits, trenches and stairwells leading down are all places where the concentration is highest and the oxygen lowest. That is why sensors are mounted low, why emergency exhaust takes suction near the floor, and why entering a pit after a release is one of the most dangerous things a person can do in a machine room.
Why This Is the Correct Answer
Refrigerant vapor is denser than air and settles into the lowest available space. A person standing may feel fine while the concentration at knee level is already dangerous, and anyone who bends down, kneels or steps into a pit moves into the worst of it.
Why the Other Options Are Wrong
Option B: High at the ceiling, because the vapor warms and rises quickly toward the vents
The vapor is much heavier than air and sinks rather than rising. Sensors and exhaust pickups placed only at ceiling level would miss a dangerous accumulation building down on the floor.
Option C: Evenly throughout the room within a few seconds of the release into a thin haze
Mixing does happen eventually, but not within seconds, and the layer near the floor stays the most concentrated for a long time. A room does not become uniformly safe that quickly.
Option D: Close around the chiller itself, held in place by the machine's insulation and its jacket
Insulation and jacketing cannot contain vapor that has already escaped the machine. Once the charge is out it spreads and settles across the room, well away from the chiller.
Memory Technique
Refrigerant falls. The danger is at your feet, not over your head.
Reference Hint
Refrigerant vapor is heavier than air and accumulates at floor level and in pits, displacing breathable air there first.
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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