Refrigerant & Oils Flashcards
A _________ is any fluid that picks up heat by evaporating at a low temperature and pressure and gives up heat by condensing at a higher temp and press (volatile fluid)
refrigerant
Main categories;
- CFC - Chloroflurocarbons
R-12, R-11 : Today these refrigerants are used very _______, in normal refrigeration systems
rarely
Main categories;
- HCFC - Hyrdochloroflurocarbons
R-22, MP39, R-123: Today these refrigerants are being phased out due to the _______ depletion potential of the chlorine atoms in the mixture
ozone
Main categories;
- HFC - Hydroflurocarbons:
R-134a, AZ-50 (R-507): This family of refrigerants are the long term replacements for the CFCs and _____
HCFC’s
Main categories;
- HC - Hydrocarbons
R-12a, R-22a : These refrigerants are either pure or mixtures of hydrocarbon molecule such as _______
propane
Main categories;
- HFO - Hydro fluro olefin
R-1234uf (solstace of honeywell): Being developed for the __________ market
automotive
Main categories;
- Ammonia
R-717: Naturally occurring refrigerant that is normally used in _________ applications
industrial
Name the three refrigerant properties?
Chemical, Physical, Thermal
Refrigerant classification: Ashrae Standard adopted by the B-52 Refrigeration code refrigerants classified as to their toxicity and flammability;
Group A1: Low toxicity, ___ flammability
Group A3: Low toxicity, ______ flammability
Group B1: Higher toxicity, ___ flammability
Group B2: Higher toxicity, _______ flammability
A1. Low
A3. higher
B1. Low
B2. higher
Definitions: Pure fluid
A fluid when used in refrigeration cycle does not change in _________ composition. Or saturation temperature as they evaporate or condense at a constant temp
R-12 , R-134A
volumetric
Definitions:
Blend: Refrigerants consisting of mixtures of two or more different chemical compounds
Azeotrope: A refrigerant blend when used in refrigeration cycle does not change volumetric composition or saturation temperature appreciably as they evaporate or condense at a _______ temperature
-R-507 , R508B
constant
Definitions:
Zeotrope: Blends, when used in refrigeration cycle, that change volumetric composition and saturation temperature to varying extent as they evaporate or condense at a _______ temperature
R-401A (MP39)
constant
Definitions:
Glide: The difference between the starting and ________ temperature of a phase change process by a refrigerant at a constant temperature
ending
Definitions:
Fractionalization: A change in the composition of a blend by preferential evaporation of the more ________ component or condensation of the less volatile component
volatile
Definitions:
Critical Temperature:
- The highest temperature at which a refrigerant can exist as a liquid. When a refrigerant reaches its critical temperature it can no longer be condensed into a ________
- Critical pressure: The vapour pressure at the _______ temperature
- liquid
2. critical
Refrigerants;
- Storage temp not to exceed ___C( 130F)
- Working temp not to exceed ___C (120F)
- 54C
2. 49C
Refrigerant Oils: Purpose of oil in a system;
- Lubrication; The separation of moving parts by a thin film of ___
- ________ friction
- Prevent _____
- Create a ______ seal
- Act as a coolant in _______
- Dampens noise in compressor ________
- oil
- minimize
- wear
- fluid
- compressor
- crankcase
Synthetic oils must be stored in ______ containers
metal
Oil Properties:
- Viscosity:
- Floc point: The point at which the wax will separate from the ____ (temp rating)
- Pour point: Temp at which it ceases to _____
- Dialectic Strength: A measure of an oils resistance to _______ current
- how thick or thin oil is
- oil
- flow
- electric
Oil Properties: Viscosity;
- Quality of how _____ the oil is
- Measured in ____: Saybolt Seconds Universal
- Higher the number means _______ the oil
- Viscosity decreases as refrigerant mixes with the ____
- Viscosity decreases with an ________ in temp
- Thick
- SSU
- thicker
- oil
- increases
Viscosity:
- A refrigerant oil must maintain a ______ enough viscosity to properly function at the highest normal temp in the system
- high
2. liquid
Vacuum Pump Oil:
- Lubricates and seals at the operating temperatures usually found in a ______ pump.
- Very low vapour pressure so that the oil does not vaporize at low levels of ________
- High viscosity index assures proper _______ at high and low pressures
- vacuum
- pressure
- lubrication
