Natural Gas & Carbon Monoxide

Question 1

What pressure is Natural Gas distributed throughout the UK

Answer 1

85 bar pressure

Question 2

What are the high pressure pipelines that distribute Natural Gas throughout the UK called

Answer 2

National Transmission System (NTS)

Question 3

From the National Transmission System NTS, natural gas is distributed to where and at what bar pressure.

Answer 3

To local distribution zones called medium pressure system at 25 bar.

Question 4

At what point is the drenching agent, ethyl mercaptan added?

Answer 4

When the gas supply is staged down to a much lower pressure for domestic use at distribution sites.

Question 5

Who is legally responsible for dealing with natural gas leaks?

Answer 5

The Gas Authority

Question 6

What is the safety cordon at a domestic natural gas leak?

Answer 6

25 metres

Question 7

What is the safety cordon for a ruptured high/medium pressure pipeline or building filled with natural gas?

Answer 7

200 metres

Question 8

What is the safety cordon from a ruptured high/medium where gas jet is directed through a congested region?

Answer 8

600 metres

Question 9

What is the safety cordon from a mass release of bulk storage of natural gas?

Answer 9

1000 metres

Question 10

At incidents involving large gas release or evacuees, a full informative and stop is required detailing what information?

Answer 10

• premise involved
• number of evacuees
• where they were evacuated to
• if they were allowed to return

Question 11

A jet of gas at 25-85 bar pressure will cause what?

Answer 11

Physical damage to its surroundings and people and generate a jet like noise.

Question 12

What should be considered when turning off a high pressure system?

Answer 12

It can take up to an hour to turn off as the gas has to be staged down to prevent rupture.

Question 13

Where should station personnel gather information on the risks on theirs wan ground which may hold large supplies of natural gas?

(6 answers)

Answer 13

• 72Ds
• Local knowledge
• ORD
• On site specialist/responsible person
• Chem Data
• Other specialist advice

Question 14

Where should appliances and crews be positioned at a suspected gas leak?

Answer 14

Appliances a minimum 25 metres away.
Personnel NOT in direct line of sight to the building
Angle greater than 45 degrees to front and rear

Question 15

Under what circumstances could a crew be committed to the hazard zone?

Answer 15

To save life or for other essential duties.

Question 16

When do calls to domestic CO detector go from HAZMAT level 1 to HAZMAT level 2?

Answer 16

Where there is a suspected large release or persons are reported trapped.

Question 17

When considering whether to evacuate the IC should consider what?

Answer 17

If they can remain in a place if safety:
•indoors with the doors and windows shut
•with Air Con systems shut down
•with naked flames extinguished

Question 18

If evacuation is considered necessary, what should be considered by the IC?

Answer 18

• prevailing weather conditions and wind direction
• minimum distances required by the pertinent procedure or through RA
• actions for patients if premises such as hospitals fall within the HZ
• pass the details of those who refuse to leave onto the police

Question 19

Under what circumstances should crews be commmited to a domestic gas leak to shut off the supply?

Answer 19

When they are not at risk from a gas explosion and donned BA and full structural PPE.
Where there is a risk to life in surrounding buildings or critical infrastructure.

Question 20

If the GA representative requests the LFB to remain at an incident to provide cover for them, who should the IC seek authority from?

Answer 20

The duty DAC