Commercial Refrigeration Systems Flashcards
7 cards from real CFC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Commercial Refrigeration Systems flashcards as text
In a commercial display case, what is the primary function of the anti-sweat heaters on door frames?
Answer: Prevent condensation on door frames and gaskets
Anti-sweat heaters warm door frames and glass edges above the dew point to prevent condensation that would obstruct customer view and cause corrosion.
What refrigerant charge condition is indicated when both suction and discharge pressures are lower than normal in a commercial system?
Answer: System undercharged or low refrigerant
Low refrigerant charge reduces mass flow rate, causing both suction and discharge pressures to fall below normal operating levels.
Which type of defrost cycle is most energy-efficient for commercial refrigeration cases operating near freezing temperatures?
Answer: Off-cycle defrost
Off-cycle defrost simply stops the refrigeration cycle and allows ambient heat to melt frost, consuming no additional energy compared to electric or hot gas methods.
A technician finds oil logging in the evaporator of a commercial refrigeration system. What is the most likely cause?
Answer: Insufficient refrigerant velocity to carry oil back to compressor
Oil logging occurs when refrigerant velocity is too low to entrain oil and return it to the compressor, often from oversized piping or low load conditions.
In commercial refrigeration, a thermostatic expansion valve (TXV) bulb should be mounted on the suction line:
Answer: At the 4 or 8 o'clock position on a horizontal suction line
Mounting the TXV sensing bulb at the 4 or 8 o'clock position on a horizontal suction line ensures it senses refrigerant temperature accurately without being affected by oil pooling at the bottom.
Which R-22 replacement refrigerant is approved as a drop-in for existing commercial medium-temperature refrigeration systems without changing the oil?
Answer: R-407C
R-407C has thermodynamic properties similar to R-22 and is compatible with existing mineral oil or alkylbenzene oil, making it suitable for retrofit applications.
What is the purpose of a suction-line accumulator in a commercial refrigeration system?
Answer: Prevent liquid refrigerant slugs from reaching the compressor
A suction-line accumulator catches liquid refrigerant before it reaches the compressor, protecting it from hydraulic damage during flood-back conditions.