System Lubrication and Purging Flashcards
7 cards from real CARO practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 System Lubrication and Purging flashcards as text
An operator measures a condenser pressure that is well above the saturation pressure for the liquid temperature leaving the condenser. What does this most likely indicate?
Answer: Noncondensable gases are present
Pressure above the saturation pressure at the measured temperature points to air or other noncondensables in the condenser.
When an ammonia purger vents noncondensables, the vented gas is usually routed through what before release?
Answer: Into a water bubbler or water tank that absorbs any ammonia
Ammonia is very soluble in water, so passing the purge gas through water captures ammonia that comes along with the air.
How does an automatic refrigerated purger separate air from ammonia?
Answer: It cools the mixture so the ammonia condenses and the air is left to vent
A purger chills the sampled gas below the condensing temperature, so ammonia condenses and returns while the noncondensables collect and are vented.
Why is it important to remove noncondensable gases from a refrigeration system?
Answer: They raise head pressure, which wastes compressor energy and lowers capacity
Higher condensing pressure makes the compressor work harder, so it uses more power and moves less refrigeration.
How can air most commonly enter an ammonia system?
Answer: Through leaks in parts of the system running below atmospheric pressure (vacuum)
Low-side parts that run in a vacuum can pull air in through leaking seals, valve packings, and fittings.
Before adding oil to an ammonia compressor, what should the operator check?
Answer: That the oil is the type and grade the compressor manufacturer specifies
Using the specified oil type and viscosity grade keeps the compressor properly lubricated and avoids compatibility problems.
Oil that has been drained from an ammonia system should generally be handled how?
Answer: Treated as used oil, collected and disposed of according to regulations
Drained oil is contaminated and should not go back into the system; it must be collected and disposed of under environmental rules.