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
.
Why should oxygen or compressed air never be used to pressurize a system?
Oxygen or compressed air should never be used because
they contain moisture
, and moisture reacts with oil in the system to for acids ( organic solids ) R12 R22 R502 R134a will hydrolyze ( a chemical reaction ) with water forming hydrochloric and hydrofluoric acids and more water.
Why should oxygen or compressed air?
The low pressure side of the system must not be pressurized two more than. … Why should oxygen or compressed air never be used to pressurize a system?
You should never use oxygen because it will oxidize boil which may generate pressures to the point of exploding
. 5.
What compressed gas is used to pressurize refrigerant tubing?
Nitrogen (oxygen free / OFN)
is the gas most commonly used to pressure test systems prior to refrigerant charge, or as part of servicing following refrigerant recovery.
What should a technician use to determine a safe pressure for leak testing?
When leak checking a system, NEVER pressurize the system with oxygen or compressed air. When mixed with refrigerants, oxygen or compressed air can cause an explosion. To determine the safe pressure for leak testing,
check the data plate for the low-side test pressure value
.
When a system is in deep vacuum you should never what?
When a system is in deep vacuum; 1.
Never add refrigerant to the system
.
What vapors does a deep vacuum pull out of the system?
The main reason for pulling a vacuum on a system is to rid it of unwanted gases, mainly
air and water vapor
. Air, being a noncondensable, will get trapped in the high side of a refrigeration system because the condenser's liquid seal (subcooled liquid) at its bottom prevents the air's passage.
What percentage of oxygen is in medical air?
The air around you is made up of
21%
oxygen. Most of the rest of the air consists of nitrogen which is not used by the body.
Do we breathe in air or oxygen?
We get oxygen by
breathing in fresh air
, and we remove carbon dioxide from the body by breathing out stale air.
Is compressed air same as oxygen?
Compressed air is made of
the same air
you breathe in and out, but that air is compressed into a smaller size and kept under pressure. … Atmospheric air and compressed air are both made up of: 78% Nitrogen. 20-21% Oxygen.
How will air trapped in the A C system affect system performance?
When air enters a refrigeration system, it collects in the top of the condenser and is trapped. … Air will
cause a reduction in condenser surface area
, which will cause a high condensing pressure. Air can enter the refrigeration system through a leak in the low side of the refrigeration system.
Is 1000 microns a good vacuum?
ASHRAE recommends
evacuation to below 1000 microns for moisture removal
and below 500 microns after replacing a compressor. … A high quality vacuum pump will be able to take you down to 200-500 microns. With the system almost completely free from water vapor, you are ready to put the refrigerant back in the system.
Why is nitrogen used for leaks instead of compressed air?
Nitrogen gas possesses numerous physical qualities that make it uniquely suited to leak testing. It is an
inert gas
, which is hardly reactive under normal industrial conditions. Gaseous nitrogen also prevents oxidative/corrosive reactions by eliminating water vapor and oxygen from within sensitive equipment.
Which refrigerants is very high pressure and generally does not need to be recovered?
Co2 refrigerant R-744 (Carbon dioxide)
is a very high-pressure refrigerant and generally does not need to be recovered.
Which refrigerants must be recovered before opening?
Chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs)
have which of the following in common? They must be recovered before opening or disposing of appliances. After 1995, supplies of CFC refrigerant for equipment servicing will come from; recovery and recycling.
Which one of the following is classified as a low pressure refrigerant by the EPA?
HCFC-123
used in chillers is a “low-pressure refrigerant” under EPA's Section 608 regulations to replace CFC-11.
