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تسرب بخزان5 طن غاز بروبان (بتوجاز ) وتريد تفريغه ماذا تفعل ؟
INCIDENT ACTION PLAN
TACTICAL OBJECTIVES
The primary tactical objectives are to control ignition sources and disperse the flammable
vapors being released from the aboveground tank using fog streams from
hoselines.
The secondary objective is to secure the leak and repair the damaged container
with the assistance of the local propane dealer.
METHODS FOR CONTROL OF LEAKING GAS (NO FIRE)
The first initial action by the Incident Commander should be to implement site management
procedures, (e.g., isolate the area and deny entry, remove bystanders to a
safe area, and establish Hazard Control Zones.)
A call for technical assistance from the local propane dealer should be made as
soon as possible. The dealer should be briefed on the nature of the problem so that
the proper tools and parts are dispatched to the scene.
Firefighters in full protective clothing and SCBA should deploy hoselines to disperse
and dilute the flammable gas away from the primary source of ignition. Two
1-1/2 or1-3/4 inch hoselines flowing100 gpm or higher are recommended. Fog
nozzles should be placed on narrow angle fog patterns to aid in dispersing the flammable
gas. The placement of the hoselines should be such that the propane gas is
directed away from nearby structures.
• A Combustible Gas Indicator (CGI) should be used to determine if hoselines are
effective in dispersing the gas. Readings should be taken with potential exposures
in mind; (e.g., downwind areas where severe exposures could exist, inside
occupied areas or locations where the gas could travel, downhill, below grade
and other confined areas.)
(a) A reading should be taken downwind to see if the gas is dispersed. When
Combustible Gas Indicator (CGI) readings indicate levels of10% of the
lower flammable limit or greater, additional charged handlines should be in
place as a precautionary measure.
(b) A reading should be taken outside and inside nearby structures to determine if
propane gas has migrated into the building. If CGI readings exceed10% of
the lower flammable limit, the entry team should withdraw and ventilate
the building using positive pressure ventilation. Ventilating the interior
space will lower the level of flammable vapors inside the structure.
(c) When Combustible Gas Indicator (CGI) readings indicate detectable levels
of flammability, responders should not activate potential ignition sources
(e.g., light switches, garage doors, or interior heating and air conditioning or
ventilating equipment).
(d) Other readings should be taken to assure that the propane gas is not drifting
towards other exposures, structures or hazards.
(e) Propane gas dissipates rapidly but may settle in low unventilated areas.
Readings should be taken in sewers, manholes, or below grade areas.
• Flammable Atmospheres—OSHA and most national consensus standards consider
a flammable atmosphere containing concentrations of10% or less of the
lower flammable (explosive) limit (LFL) as acceptable for conducting rescue
operations.
(a) Areas with flammable concentrations of10 to20% of the LFL are considered
hazardous and should not be entered by rescue teams unless they have
proper PPE.
(b) As flammable readings rise above20%, the level of risk to responders also
rises. Rescue personnel operating in flammable concentrations of50% of the
LFL or greater should immediately leave the hazardous area.
• Additional hoselines are recommended to back-up the team dispersing the
flammable gas and to stand-by to protect exposures in case of accidental ignition.
• A repair crew can gain access to the dome cover and valve on the top of the tank.
A qualified propane repair person with proper protective clothing and equipment
can determine the problem and make emergency repairs by either shutting
the valve or replacing the damaged equipment. All emergency repair operations
must be done under the protection of wide-angle fog from a hoseline dedicated
to the protection of the repair crew. Once the replacement parts are in place the
area should be checked with a CGI before the hoselines can be shutdown.
Additional factors to consider for this operation include:
• Hoselines should be positioned so that they are effective in dispersing the
flammable gas.
• Where possible, the back-up or standby hoseline should be supplied from a
water supply that is independent of the primary hoselines dispersing flammable
vapors in case the primary handline loses its water supply.
• Before leaving the scene the interior of buildings in the area should be
checked again for flammable vapors using a Combustible Gas Indicator
(CGI). There should be no reading on the CGI.
Becuase propane is denser than air, could sink into enclosed area thus poses explosion and fire risk. The leak control measures from the MSDS will help further to Mr Joshua's great contribution here. Furthermore it is important to carry out a RA of this incident.