Electrical and Natural Gas Emergencies. DANGER. Firefighter Safety. Controlling the Utilities. Natural Gas. Electricity. 1. 0. 1971. Properties of Natural Gas. Properties of Natural Gas. Odorless – Colorless - Tasteless.
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DANGER Firefighter Safety Controlling the Utilities Natural Gas Electricity
1 0 1971 Properties of Natural Gas
Properties of Natural Gas Odorless – Colorless - Tasteless Methyl Mercaptan is added to give it it’s distinguishable “rotten egg” odor Odorized natural gas is detectable at concentrations significantly less than 1%
Properties of Natural Gas Non-Toxic 94% - methane 4% - ethane Often listed as a “Hazardous Material” due to it’s flammability, not it’s toxicity Only through it’s ability to displace oxygen can it pose an asphyxiation hazard
Natural Gas 0.7 Air = 1 Will rise and collect near the ceiling Propane 1. 56 Properties of Natural Gas Vapor Density 30% lighter than air
Flammable Range Properties of Natural Gas Flammable Limits Too Rich 14% 4.5% Too Lean
Properties of Natural Gas Heating Value 1,000 BTU per cubic foot
Properties of Natural Gas Combustion Products Complete combustion = heat, carbon dioxide & water vapor Incomplete combustion = carbon monoxide
Natural Gas - 1163º F Propane - 957º F Gasoline - 632º F Properties of Natural Gas Ignition Temperature
Properties of Natural Gas Natural Gas Supply
Properties of Natural Gas Comparisons
Natural Gas Equipment Distribution System
Natural Gas Equipment Distribution System Each time the pressure is reduced, over pressure protection is provided by a relief valve or automatic shut off A relief valve venting gas to the atmosphere is performing its proper function and should never be cut off or restricted until the gas company arrives and makes corrections to the system
Natural Gas Equipment Piping
POLYETHYLENE PIPE Natural Gas Equipment Piping Polyethylene pipe is buried with a 12 gauge wire for ease of locating – it has nothing to do with grounding or bonding
Natural Gas Equipment Piping Distribution piping is normally buried between 12” and 18” below ground level
Square - Handle T - Handle L - Handle Natural Gas Equipment Shut-off Valves Side View
Closed Position Open Position Natural Gas Equipment Shut-off Valves Top View
Natural Gas Equipment Typical Residential Installation
Natural Gas Equipment Typical Residential Installation Regulator Relief Valve Valve
Natural Gas Equipment Typical Residential Installation Meter
Natural Gas Equipment Commercial Installation Meter Regulator Valve
Natural Gas Emergencies Types of Emergencies Odors / Leaks Fire Outside Building Inside Building
Natural Gas Emergencies Emergency Response Odors / Leaks • Inside • Approach incident from upwind, if possible. • Position apparatus at least 150” from scene. • Investigate for the source of the odor. • WCB prohibits entry into a confined space having an atmosphere containing over 10% LEL combustible gas • 4) If a strong odor is encountered or leak is confirmed, evacuate the bldg. of all occupants.
Natural Gas Emergencies Emergency Response Odors / Leaks Inside 5) Notify PSE- Gas Op's to respond. 6) Ventilate the bldg. by opening doors & windows. Remember to open windows on top. 7) Do not operate electrical switches / telephones.
OK Natural Gas Emergencies Emergency Response Odors / Leaks • Inside • Use only intrinsically safe radios / handlights. 9) If a leak is confirmed, the IC should determine if it can be stopped or if the gas needs to be shut off at the valve.
Natural Gas Emergencies Emergency Response Odors / Leaks Inside 10) Hand tools should be spark-proof (1663 / 1665). 11) Gas valves turned OFF by FD personnel SHOULD NEVER be turned back on without PSE- Gas Op's on scene. 12) No one should re enter the bldg. until PSE- Gas Op's has secured the leak and determined that it is safe to enter.
Natural Gas Emergencies Emergency Response Odors / Leaks • Outside • If unignited gas is escaping from the ground, either from an excavation site or from an open pipe outside of a bldg., notify PSE- Gas Op's immediately. • Establish a safe area around the incident scene. • Extinguish all open flames. • Check surrounding bldgs., especially basements, for the presence of gas. • Gas can migrate through the ground, following pipes or natural stratifications in the earth.
Natural Gas Emergencies Emergency Response Odors / Leaks Outside 5) Restrict or re-route traffic until PSE- Gas Op's personnel can bring the gas flow under control. 6) Although water fog streams can be used to disperse escaping vapors, they are usually ineffective since the lighter-than-air gas naturally rises. 7) If water fog is used, caution must be exercised to avoid filling excavation sites with water.
Natural Gas Emergencies Emergency Response Odors / Leaks • Outside • FD personnel should never clamp or crimp a gas line. Static electricity could ignite escaping gas, resulting in a sudden and violent ignition. • Hand tools should be spark-proof (1663 / 1665).
Natural Gas Emergencies Emergency Response Fires • Inside • Notify PSE- Gas Op's immediately upon receipt of alarm. • The IC should determine if the gas can safely be shut off inside the bldg. or at the meter.
Natural Gas Emergencies Emergency Response Fires Inside 3) In certain industrial / commercial settings, turning off the gas supply can seriously interrupt important and costly industrial processes and should only be done upon evaluation with company personnel and PSE- Gas Op's. 4) If the gas supply cannot be shut off, the surrounding combustibles should be kept wet with a fog stream.
Natural Gas Emergencies Emergency Response Fires • Outside • Notify PSE- Gas Op's immediately upon receipt of alarm. • The best method of controlling outdoor gas fires is to shut off the gas flow. • In most cases, FD personnel should not attempt to extinguish the fire while the gas is still escaping. • BURNING GAS WILL NOT EXPLODE.
Natural Gas Emergencies Emergency Response Fires Outside 5) Secure the area and protect exposures, if necessary. 6) IF it is necessary to extinguish the fire before the gas flow can be stopped, use a Dry Chem extinguisher aimed at the base of the flame and wet the surrounding area with water fog to prevent the re-ignition of combustibles.
Primary Lines Secondary Lines Transformer Cable TV / Telephone Lines Insulators Electrical Hazards Distribution System
Electrical Hazards Distribution System • Primary Lines • located at the highest level of the pole • carry the greatest amount of power • normally bare wire, which gives them the “look” of support cables
Electrical Hazards Distribution System • Secondary Lines • located one level below the primary lines, at the second-highest level of the pole. • carry voltages less than primaries. • may be coated for protection from the elements. This coating DOES NOT provide insulation from live current.
Electrical Hazards Distribution System • Cable TV / Telephone Lines • located at the lowest level of the pole • carry lower voltages than primaries & secondaries • should be coated for protection from the elements. This coating DOES NOT guaranty insulation from live current. • should always be considered dangerous due to back-feeding or cross-conduction.
CAUTION CAUTION CAUTION CAUTION Electrical Hazards Types of Emergencies Downed Wires Pole / Transformer Fires Vehicle / Pole Accidents Wires on Vehicle Vehicles Contacting Wires Manhole Fires Substations
Electrical Hazards Step Potential The voltage decreases as the distance from the point of contact increases
Electrical Hazards Types of Emergencies Downed Wires
Electrical Hazards Types of Emergencies Downed Wires Always treat all downed wires, including Cable TV & telephone wires, as energized at high voltage until proven otherwise.
Electrical Hazards Types of Emergencies Downed Wires • It is impossible to determine if a wire is energized by its appearance. • Never attempt to move or cut any downed conductors. Remember, wooden or fiberglass pike poles MAY BE conductive.
Electrical Hazards Types of Emergencies Downed Wires • Upon arrival • Establish a safety zone and secure the area. • If possible, the safety zone should extend a minimum of two full span lengths of wire in each direction beyond the downed wire. • poles may break and fall due to stress • wires can slip through insulators and sag to the ground • wire may be contacting metal fences, guard rails, buildings, etc.
Electrical Hazards Types of Emergencies Downed Wires Safety Zone
Electrical Hazards Types of Emergencies Downed Wires • Any high-voltage wire, when disturbed, can get out of control. • FF boots do not guaranty insulation from energized wires. • NO HIGH VOLTAGE wire is insulated. The coating sometimes seen is to provide protection from the elements.
Electrical Hazards Types of Emergencies Downed Wires • Bodies in contact with live wires may be energized. DO NOT TOUCH the individual until the wire is tested dead and cleared form the body. • Wires should not be assumed dead until they are tested dead or certain assurance from BC HYDRO personnel is rec’d.