Small chillers often use centrifugal or screw compressors that are semi-hermetic.
The sale of CFC and HCFC refrigerants was restricted to certified technicians on which of the following dates?
November 14th , 1994
November 14th, 1994 is the correct answer.
What is the impedance symbol?
The symbol or letter for impedance is Z and it is represented by writing its magnitude and phase.
Is it possible for the refrigerant to escape from a low-pressure system?
The pressure in the refrigeration system is lower than the atmosphere so there is change outside air coming in to the refrigeration system.
The leak rate is based on a percentage of the total charge depending on the amount of refrigerant lost in the previous 12 months.
Repair requirements is the current leak rate projected over a consecutive 12-month period.
What exactly does a sling psychrometer measure?
Wet and dry bulb temperature
A sling psychrometer is a device that consist of two thermometers fitted in a hinged bracket used for spinning the two thermometers. One of the bulbs is kept moist with distilled water on a sock or wick placed over the thermometer's tip. As the thermometers are rotated, evaporation of water from the wick lowers the temperature indicating a lower temperature than that of the dry-bulb thermometer. This is the Wet bulb temperature which will be lower than the dry bulb and can never be above dry bulb measurement. The lower the relative humidity, the lower the wet bulb temperature. The difference in the two bulbs readings can be applied to a psychrometric chart to calculate relative humidity and other properties of air.
True or false: The receiver is not part of a refrigeration system's low side?
The receiver is placed in the liquid line, which is not part of the low side.
Except for commercial and industrial process refrigeration, EPA regulations mandate that any appliance containing more than 50 pounds of refrigerant be repaired if the leak rate ________ reaches of the charge per year.
EPA regulations require that any appliances containing more than 50 pounds of refrigerant, except for commercial and industrial process refrigeration, must be repaired when the leak-rate exceeds 10 percent of the charge per year.
THIS BECAME EFFECTIVE JANUARY 2019:For comfort cooling appliances with 50lbs or more, leak inspections must be conducted once per client per calendar year until such time your leak-rate calculations show that you have not exceeded the threshold limit of 10% for one year. In addition to this, after leak repairs on any of these appliances types you will need to conduct an initial test for verification as well as a follow-up. PREVIOUSLY the allowable leak rate was 15% for comfort cooling with 50lbs or more.
How often should leaks in commercial refrigeration equipment's recovery or recycling units be checked?
Commercial refrigeration equipment with a full charge of 500 or more pounds should have an inspection every 3 months. If they have between 50 and 500 pounds, the inspection can occur once per year. Comfort cooling appliances can have an inspection once every year as well.
Heat pumps that use R-134a should be checked with ________ for leaks.
Heat pumps that use R-134a should be leak-checked with pressurized nitrogen
Which of the following gases is used in leak detection?
HCFC-22 can detect much smaller leaks. The helium molecules are much smaller than the nitrogen molecules. This helps it better pick up leaks.
The refrigerant was recovered and stored in a refillable cylinder before replacing the condenser coil in a high-pressure system. This is the refrigerant.
can probably be charged back into the system.
Prior to replacing the condenser coil in a high pressure system, the refrigerant was covered and stored in a refillable cyclinder. The refrigerant can probably be charged back into the system.
When the leak rate exceeds ________ the charge per year, EPA regulations require that leaking commercial or industrial process refrigeration equipment be repaired.
EPA Regulations requires the leaking commercial or industrial process refrigeration equipment must be repaired when the leak-rate exceeds 30% of the charge per year.NEW LEAK THRESHOLDS BECAME EFFECTIVE JANUARY 2019: Leak rates for commercial refrigeration now cannot exceed 20 percent and cannot exceed 30 percent for industrial process refrigeration. The previous were 30% for both commercial refrigeration and industrial process refrigeration.
Before switching to liquid charging on an R-410a system with a water-cooled condenser, you must first charge with vapor to a pressure of at least ________.
When charging an R-140a system that uses a water-cooled condenser, you must first charge with vapor to a pressure of at least 120 psig before switching to liquid charging.
What is the use of soap bubble testing?
to pintpoint leaks
Soap bubble testing is used to pinpoint refrigerant leaks.
Between a heat pump and an air conditioner, what's the primary difference?
The reversing valve is the component that will reverse the flow of refrigerant when changing from air conditioning to heating.