Chapter 114- Refrigerants Flashcards Preview

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Flashcards in Chapter 114- Refrigerants Deck (26):
1

Liquid refrigerants are defined as

Liquids that, atmospheric pressure, have a boiling point considerably lower than that of water

2

There are six groups of refrigerant

B1, b2, b3, a1, a2, a3

3

The B group is characterized by its

Toxicity

4

The A group is characterized by its

Low toxicity

5

The number determines its

Flammability

6

A1 is defined as

Non toxic, non flammable

7

A2 is defined as

Flammable, low toxicity

8

A3 is defined as

Low toxicity, highly flammable

9

B1 is defined as

Highly toxic an non flammable

10

B2 is defined as

Flammable and highly toxic

11

B3 is defined as

Highly flammable, highly toxic

12

Ideal refrigerants have these qualities

Low boiling point at atmospheric pressure
Low condensing pressure
An inoffensive odour
A non poisonous nature
Non corrosive action on metals
Nonflammable and non explosive nature when mixed with air
Reasonable price

13

Thermodynamic properties include

Pressure
Temperature
Volume
Density
Enthalpy
Entropy

14

What is the pressure temperature relationship of refrigerants

The saturation temperature of a liquid in a closed vessel can be raised or lowered by raising or lowering the pressure in a vessel.

15

What are standard conditions of a refrigerant

Standard evaporator temperature of -15 degrees Celsius
Standard condenser temperature of 30 degrees Celsius

16

Specific volume is defined as

It is necessary to know the specific volume of a refrigerant while it is a liquid or a vapour under conditions required in the refrigerator it's specific volume is the the change in volume between states

17

Density is defined

The density of a liquid refrigerant, required to know the size of valves and piping in a refrigerator. Expressed in kg/ meters cubed

18

Enthalpy is defined as

Sensible heat in a liquid
Sensible heat plus latent heat in a vapour

19

Refrigerating effect

The effect of heat being taken away from the surroundings so that cooling may take effect, vapour to a gas requires latent heat energy this is what causes the cooling effect in a refrigerator

20

Physical properties of refrigerants

Miscibility
Leakage tendency
Odour
Toxicity
Flammability/ explosiveness
Moisture reaction

21

Miscibility is defined as

The ability of oil to be absorbed into a refrigerant and vice versa is miscibility

22

Leakage tendency is defined as

The leakage tendency of a liquid may include factors like
Operating pressure
Viscosity
Density
Molecular mass of the refrigerant
Larger the molecule, the less of a chance it has to escape
Fat kids can't run
for long

23

Odour is

What you smell
Idiot
Used to detect is a refrigerant leak is taking place

24

When a halide torch is us for leak detection what should be done

Provide ample ventilation

25

Toxicity is defined as

When e posed to a flame the may react and decompose forming highly toxic vapours, or may be highly toxic to begin with

Will fucking kill you

26

Moisture reaction must be avoided for two reasons

May cause ice to form between valve and valve seat
Could result in corrosion
Sludge forming
Deterioration of the motor insulation