1. Service Delivery 4
Compressed Gases

2. Aim
To familiarise students with the procedures for dealing with compressed gases.

3. Learning Outcomes At the end of the session students will be able to:
State the properties of compressed gases
List the hazards and appropriate operational procedures for incidents involving compressed gases.

4. Introduction
Compressed gases are stored, transported and used in a variety of ways
A particular gas may be flammable, explosive, toxic or possess a combination of these features
Operations at incidents involving compressed gases will vary according to volume, method of containment, specific properties of gas involved and nature of surrounding exposures.

5. Storage Nature of the gas Quantity of the gas
Extent of threat depends on;
Nature of the gas
Quantity of the gas
Nature of premises concerned and surrounding exposures.

6. Storage Cylinders Industrial gases colour code BS 349
Medical gases colour code BS1319
Threat from fire
Flying fragments up to 100 metres
Rapid spread of fire between adjacent cylinders.

7. Safety devices
Bulk;
Pressure relief valve
Emergency control valve.

8. Safety devices Cylinders; Pressure relief valve Bursting discs
Fusible plugs.

9. Storage.
Bulk storage;
Spheres

10. Storage.
Bulk storage;
Tanks

11. B.L.E.V.E. Boiling Liquid Expanding Vapour Explosion
Hydrocarbon flame burns up to 2,000 °C
Steel weakens as temperatures exceed 350/400 °C
Dry wall attains temperature of °C
Severe hazard unless massive cooling.

12. B.L.E.V.E. Firefighting procedures
If no risk to life or property, give serious consideration to a “non-attack” strategy
Where only property is at risk, it may still be necessary to consider a “non-attack” strategy.

13. B.L.E.V.E. Firefighting procedures
If attacking the fire, immediate cooling must be undertaken, concentrating on the exposed vapour space
Personnel should be fully briefed and made aware of the hazards.

14. LPG Liquified petroleum gas
Colourless
Liquid (under pressure or low temperature)
Flammable
Explosive
Odourless (has stenching agent added)
Heavier than air
High co-efficient of expansion.

15. LPG Butane Propane Flash point -60 °C Boiling point -6 °C
Explosive limits 1.5% - 9.0%
Flash point °C
Boiling point °C
Explosive limits 2.4% - 9.5%.

16. Gas release Possible ignition sources Environmental hazards.
An unignited gas release can present a number of problems;
Large gas cloud
Possible ignition sources
Environmental hazards.

17. Leakage of LPG without ignition
Shut off leak at source
Prevent ignition
Safe dispersal of gas/vapour cloud.

18. Dealing with vapour clouds
Use of fog branches / monitors
Ground sprays projecting a flat fan spray
Ground monitors set at 45 degrees spray pointing straight up
Gas detectors to monitor effectiveness.

19. Gas dispersal
Using hand held branches, under sufficient pressure, flames and/or gas may be channeled away
Using portable monitors small leaks may be entrained into a low pressure area in the centre of the spray and directed to a safe area.

20. Gas dispersal
Several monitors can be positioned around a leak forcing gas upwards
Water curtain spray branches can be used to protect areas from gas and perhaps provide a safe escape.

21. Access and location
Isolation is the most effect method of eliminating any danger from an uncontrolled gas release.

22. Access and location If unignited; Evacuate the area
Eliminate any ignition sources
Attempt a controlled isolation
Render the area safe.

23. Access and location If ignited; Evacuate the area
Provide personal and structural protection
Controlled isolation.

24. Leakage with ignition
Do not extinguish flames until outflow has been stopped
Reduce areas of burning liquid by applying foam blanket
Monitor pressure relief valves.
Secure additional cooling
Keep cooling water away from valves to prevent freezing
Cool supporting structure

25. Acetylene Colourless Non-toxic Highly flammable
Ethereal (anaesthetic ) odour
Industrial - garlic smell / lighter than air
Decomposes in absence of oxygen or air
Ignited from static charge.

26. Acetylene Spontaneous ignition temp 335° C
Critical temperature ° C
Flammability limits % - 80%
Flame temperature ° C.

27. Acetylene cylinders Seamless steel cylinders Welded steel cylinders
Colour coding
Storage (porous mass, acetone )
General.

28. Acetylene cylinder incidents
Leaks from the cylinder safety device (if fitted ) or valve associated equipment, whether the gas has been ignited or not
Flashback from a torch into cylinder
Cylinders in vicinity of fire and subjected to heat
Shock.

29. Unignited leaks
Urgent assessment of volume released - Time and rate of discharge in relation to capacity of cylinder
Prevailing winds
150 metre ‘hazard zone.’
Total areas involved
Ignition hazards
Attempts to close leak without igniting gas
Ventilate building

30. Summary of LPG Full firefighting kit to be worn
Be aware of and use other P.P.E
Liquefiable gas
Very low flash point
Heavier than air
Stored under pressure.

31. Summary of LPG Flame impingement Container over-heating B.L.E.V.E.
Also be aware of explosion risk due to;
Flame impingement
Container over-heating
B.L.E.V.E.

32. Summary of LPG Sources of ignition Wind direction
Consider;
Sources of ignition
Wind direction
Vapour collecting (low points)
Vapour dispersal.

33. Summary of acetylene Full firefighting kit to be worn
Be aware of and use other P.P.E
Minimum number of personnel inside the 150 metre hazard zone
Do not lift any cylinders where decomposition is suspected
Do not drop cylinders.

34. Confirmation Learning Outcomes
Assessments will be based on this lesson and the corresponding study note
Learning Outcomes
State the properties of compressed gases
List the hazards and appropriate operational procedures for incidents involving compressed gases.

35. THE END