Why should oxygen or compressed air not be used to pressurize appliances to check for leaks?
Why should oxygen or compressed air NOT be used to pressurize appliances to check for leaks? Oxygen or compressed air can explode when mixed with compressor oil or some refrigerants.
Can a vacuum pump remove any type of foreign matter that enters a refrigeration system?
Some of the foreign matter that may enter a refrigeration system are acid, air, moisture (water-vapor), and heat. A vacuum pump cannot remove ANY/ALL types of foreign matter that may enter a refrigeration system. Vacuum Pumps are not designed to remove solids and sludge.
Why must you remove air from a system?
When a typical system is installed and/or serviced, air and moisture enter the system. Oxygen, nitrogen and moisture (all make up our air or atmosphere) are detrimental to system operation. Removal of the air and other non-condensibles is called degassing and removal of the moisture dehydration.
When a system is in deep vacuum you should never do what?
When a system is in deep vacuum; 1. Never add refrigerant to the system.
What is a refrigerant blend?
Blends are a combination of two or more other single component refrigerants. These blends have different chemical and interactive properties. Refrigerants are substances that are mixtures and undergo constant phase transitions from liquid to gas and vice versa.
Which of the following is true if a system will not hold a vacuum after it has been evacuated?
Which of the following is TRUE if a system WILL NOT hold a vacuum after it has been evacuated? The system is ready to be charged.
Which condition requires accessing both the high and low side of the system for refrigerant recovery?
using the system dependent (passive) recovery process, which condition requires accessing both the high and low side of the system for refrigerant recovery? it is necessary to heat the compressor and strike it with a rubber mallet.
How do refrigerant blends leak from a system?
The components of a blended refrigerant will leak from a system at uneven rates due to different vapor pressures. Therefore, the proper charging method for blended refrigerants is to weigh into the high side of the system as a liquid. throughout the evaporator and condenser respec+vely.
Which human health effects increases from damage to the stratospheric ozone layer?
Ozone depletion Decreased concentration of stratospheric ozone allows increased amounts of UV-B to reach the earth’s surface. Stratospheric ozone loss can result in potential harm to human health and the environment, including: increased incidence of skin cancer and cataracts. immune system system damage.
Which of the following refrigerants is very high pressure generally does not need to be recovered?
Co2 refrigerant R-744
What are very high pressure refrigerants?
Very high-pressure appliance means an appliance that uses a refrigerant with a critical temperature below 104 °F or with a liquid phase saturation pressure above 355 psia at 104 °F. Examples include but are not limited to appliances using R-13, R-23, R-503, R-508A, and R-508B.
Which refrigerants can be mixed?
The most commonly mixed refrigerants in the field are the replacements for R-22 — R-427A, R-438A, R-422D, and R-407C — which are often combined with the remaining R-22 in the system, said Maiorana.
What is R 744 refrigerant?
R744 is a refrigerant grade CO2, used in ultra-low, low and medium temperature refrigeration applications. As a natural refrigerant, CO2 is becoming increasingly popular due to its excellent properties, an Ozone Depleting Potential (ODP) of 0 and a Global Warming Potential (GWP) of 1.
Is R 744 flammable?
R744 has a global warming potential (GWP) of 1 and is non-flammable. However, the extremely high operating pressures of R744 and hazards associated with potentially high concentrations of CO2 in vehicle cabins or working environments means this refrigerant must be used with care.
Why is CO2 not used as a refrigerant?
The main drawback of carbon dioxide as a refrigerant is its inherent high working pressure. This pressure is much higher than that of the other natural and synthetic refrigerants mentioned. On one hand, this means that for CO2 cycles, components must be redesigned.
Is CO2 used as a refrigerant in ice cream?
Ice cream can be flashYfrozen using carbon dioxide as a directYcontact refrigerant. An emulsion of ice cream mix and liquid carbon dioxide is throttled to the saturated carbon dioxide pressure associated with the desired temperature of the frozen ice cream.