Occupational Hazards - LPG

Question 1

What is the maximum percentage of liquid fill for an LPG cylinder?

Answer 1

The legal filling capacity of containers is 80%, to ensure adequate vapour space above the liquid.

Question 2

What does the vapour space in an LPG cylinder allow for?

Answer 2

Allows for expansion of the liquid caused by an increase in temperature.

Question 3

How is excess pressure in this space relieved?

Answer 3

LPG storage containers are equipped with pressure relief valves designed to operate when the pressure in the vessel increases above certain pressure.

Question 4

In what state is LPG normally stored?

Answer 4

LPG is stored under pressure in liquid form

Question 5

What are the two (2) most common types of LPG?

Answer 5

• Propane

- Butane

Question 6

What is the difference between domestic/industrial LPG and automotive LPG?

Answer 6

When LPG is for domestic use and industrial use, it is 100% propane. When used in automotive applications, its is generally a mix of 50% propane and 50% butane

Question 7

In relation to LPG, what is the UN number, Hazchem code and D.G Class?

Answer 7

UN number: 1075
Hazchem Code: 2YE
Dangerous Goods Class: 2.1

Question 8

What is the hazard related to the LPG’s very low boiling point?

Answer 8

Due to the low boiling point of LPG (Propane -42 degree; Butane 0 degrees), as soon as it hits atmospheric temperatures it boils and becomes gas vapour.

Question 9

What is the expansion ratio of LPG (Propane)?

Answer 9

270:1 (one litre vaporises to 270 litres)

Question 10

What is the flammability range of LPG?

Answer 10

LEL 2% - UEL 10%

Question 11

Is LPG lighter or heavier than air? Explain what this means in terms of behaviour.

Answer 11

LPG vapour density is 1.5, meaning it is heavier than air.

LPG on the ground and this should be taken into account when responding to an LPG gas leak

Question 12

What does the acronym BLEVE stand for?

Answer 12

Boiling Liquid Expanding Vapour Explosion

Question 13

How is an LPG powered vehicle identified?

Answer 13

Vehicles must display red diamond on front and rear number plates of vehicles if powered by LPG

Question 14

What is the significance of two (2) red diamonds on number plates of LPG vehicles?

Answer 14

Two red diamonds are required for dedicated LPG powered vehicles and when there are two or more liquid service valves fitted to the LPG system.

Question 15

What are the Hazards of LPG (6)

Answer 15

• Very flammable and dangerous as it evaporates or boils at ambient temperature. Volatile concentrations exist before visible cloud or mist
• Contact with skin will result in severe cold burns
• Considered bulk storage when vessel had >500 litre water capacity
• Flame will flash back to source
• Large leaks may pool in low lying areas
• BLEVE (Boiling Liquid Expanding Vapour Explosion)

Question 16

List the four (4) actions for a fire (LPG):

Answer 16

• DO NOT EXTINQUISH BURNING GAS UNLESS LEAK CAN BE STOPPED
• Cool container by directing water onto upper surface until well after the fire is out
• Cut off source of gas is safe to do so
• Always stay away from tank ends

Question 17

List the five (5) actions for a leak (LPG)

Answer 17

• Eliminate all ignition sources within 200m (minimum)
• Spill or leak area should be evacuated immediately for at least 100m in all directions
• Keep up wind and to higher ground
• Use water spray or fog to knock down vapours or divert vapour clouds
• Isolate supply if possible