A chiller machine room's refrigerant and oxygen sensors have been in place for several years with no service recorded. What does that mean for the protection they provide?
Correct Answer
B) The sensors cannot be relied on until they are calibrated on the manufacturer's schedule
Gas sensing elements drift and lose sensitivity with age and exposure, and an uncalibrated sensor can sit quietly at a normal reading in an atmosphere that should have it screaming. A power light says the electronics are alive, not that the reading is true. Calibration on the manufacturer's schedule, with the date recorded, is what makes the monitor part of the room's protection rather than a decoration on the wall.
Why This Is the Correct Answer
Sensor elements degrade whether or not they have ever seen a release, so the only way to know a monitor still reads correctly is to challenge it with a known gas concentration on a schedule. A monitor that has drifted low is worse than no monitor at all, because people rely on it and plan their entries around what it says.
Why the Other Options Are Wrong
Option A: The sensors are fine as long as their indicator lights are on and no fault is displayed
An indicator light shows that the instrument has power. It says nothing about whether the sensing element still responds accurately.
Option C: The sensors improve with age, because their elements become more sensitive over time
Sensing elements lose sensitivity as they age and as they are exposed to contaminants. None of them become more sensitive over time.
Option D: The sensors only need attention after an actual release has driven them into alarm
Waiting for a release to reveal a failed sensor means discovering the failure at the moment the protection was needed.
Memory Technique
An uncalibrated sensor is a smoke detector with the battery out. It looks like protection.
Reference Hint
Refrigerant and oxygen monitors require calibration on the manufacturer's schedule to remain reliable.
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?
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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?
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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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