Refrigeration

Question 1

Explain the pressure/volume relationship

Answer 1

As the volume decreases the pressure increases and as the volume increases the pressure decreases provided that the same amount of gas is present

Question 2

Explain heat transfer

Answer 2

Heat energy transfers through either conduction, convection or radiation from an area of high heat energy to an area of low heat energy

Question 3

Explain latent heat

Answer 3

Latent heat is the energy required to change a substances state whilst keeping the temperature the same

Question 4

Explain sensible heat

Answer 4

The energy required to change a substances temperature whilst the state stays the same

Question 5

Explain super heat

Answer 5

This is the temperature of a substance above its boiling point

Question 6

Explain the purpose of a compressor

Answer 6

Compresses the refrigerant into a hot high pressure gas and pushes it around the system

Question 7

Explain the purpose of the condenser

Answer 7

Changes the state of the hot high pressure gas into a warm liquid by sub cooling it and making sure that all gas is converted to a liquid

Cools the gas with seawater

Question 8

Explain the purpose of the thermal expansion valve

Answer 8

Controls the flow of the fluid by measuring the pressure out of the evaporator

Allows the fluid to expand making it very cold

Question 9

Explain the purpose of the evaporator

Answer 9

Uses the now very cold liquid and allows the heat from inside the compartment to heat it up

The heat from the compartment superheated the fluid meaning that there will be no fluid left in the output of the evaporator

Question 10

What is the purpose of the moisture indicating glass?

Answer 10

To give you an idea of how much moisture there is in the system

Question 11

What will the moisture indicating glass show?

Answer 11

How much moisture is in the system and it will also show bubbles that have leaked into the system

Question 12

What is the Montreal Protocol agreement

Answer 12

This is an international agreement to control the amount of substances (CFC, HCFC, Halons) that are released into the atmosphere that destroy ozone

Question 13

What is the Kyoto Summit agreement?

Answer 13

An international agreement to control the output of CO2, HFC and PFCs into the atmosphere

Question 14

State 4 methods for leak detection

Answer 14

Oil slicks
Snoop 
Spectrolyne dye and UV lights
IRLDS (infra red leak detection system)
Halogen leak detector (hand held detector)

Question 15

State 3 oils used in refrigeration system

Answer 15

OM70
SUNISO 3GS
SW68

Question 16

What does hygroscopic mean?

Answer 16

It means that it can readily absorb water

Question 17

What should be used as a source of oil?

Answer 17

A newly opened sealed bottle with the closest volume to what you intend to use otherwise the oil will have time to absorb moisure

Question 18

What should be done with oil after use?

Answer 18

Collected and disposed of at a shoreside facility.

In accordance with MARPOL and local regulations

Question 19

How can oil be added to a refrigeration plant?

Answer 19

Sump filler plug
By hand pump
Dosing pot

Question 20

When will phosgene gas be created?

Answer 20

When exposed to high remperature, refrigerants can be turned into phosgene gas

Question 21

What gas is given off by fruit and veg when it decomposes?

Answer 21

CO2

Question 22

What procedures are for entering a refrigeration compartment?

Answer 22

Tell the senior rate that personnel are entering
Breathing apparatus must be available
The high and low exhaust fans are running
No smoking at anytime
The infra red leak detection system must be active and functioning correctly
Trapped personnel light works
Must enter the room in pairs
The internal door opening mechanism must work correctly

Question 23

What should be done if refrigerant gets in your eyes?

Answer 23

Flush the effected eye(s) with running fresh water and get immediate medical treatment