Flashcards in OG 6.8 Natural Gas Emergencies Deck (54)
During a natural gas emergency, restrict vehicle and pedestrian traffic to outside a ____' radius.
When checking a structure with a gas monitor, what two areas are the most important areas to check?
You should withdraw from a structure when a gas level reaches what percentage?
20% or greater
Natural gas has a lower explosive limit of what percentage?
Natural gas has a flammable range of what percentage?
5 to 15%
What items should you never bring into the natural gas hot zone?
What is the vapor density of natural gas?
What are the three types of gaspipe found in Portland?
2. Buried polyethylene
3. Poly pipe inserted in a casing
Steelpipe is used for all gas pipelines of what type?
Transmission – pressure pipelines
How much pressure is the steelpipe able to maintain?
50 - 800 PSI
What is the standard pressure for steelpipe?
Less than 50 psi
What type of gas pipe is able to ground itself to the soil?
What is the danger of buried polyethylene pipe or poly pipe in a casing, when it is damaged?
A static charge can build up causing ignition
What is the danger of Poly pipe to adjacent structures?
Little to no risk, usually localized
What is the most commonly used type of gaspipe found in Portland on new construction?
What does Northwest natural use to upgrade existing gas service?
Poly pipe inserted into a casing
What are two situations when Northwest natural always uses steelpipe?
Soil conditions require it
What is the easiest way to identify poly pipe in a casing?
1. A white plastic sleeve over the steelpipe where the pipe enters the soil at the meter
2. A large metal ring placed around the pipe just below the shutoff valve
Is a static charge is deemed to be an issue, What might crews do to remedy the situation?
Dig down to the pipe greater than 10 feet away and soak pipe with water.
What is the primary danger when dealing with encased Poly pipe?
Natural gas can travel back to the casing to the main.
Where should you never direct the hose stream on natural gas emergencies?
Into the hole
If there is a serious natural gas leak escaping outside of the structure with no fire, and there is danger to personnel, where can you shut off the gas?
The valve located at the curb just on the customer side of the property line
You should never operate any gas valve that is located where?
In the street
A gas valve that is by the curb can be usually found at what three types of facilities?
Is it okay to operate valves located on large complex gas meters at commercial locations?
Only if there is imminent life or property threat.
When approaching a residence on the natural gas emergency what should you never use at the front door?
The doorbell. Knock and enter
Is it okay to turn off the main circuit breaker to a building at a natural gas emergency?
no, this may cause a spark.
When ventilating at a natural gas emergency, what type of fans should you use?
Electric fans with explosion proof switches
When ventilating A structure at a natural gas emergency, Where should you start ventilating?
First, where the greatest concentration is, then from the top down