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First of all I work at a gas company as a Fire Equipment Maintenance Specialist in Libya. My job is to follow up and assess efficiency of fixed firefighting systems and provide plans for preventative/corrective maintenance/testing based on schedules.
One of our firefighting systems has a foam bladder tank which protects an oil tank and plant operations. My problem is when we started this project the bladder tank was built out of global standard. The foam concentrate AFFF is stored between the internal tank wall and membrane. Water gets inside the membrane which forces the foam to get out through the rated membrane. I know it is wrong and does not produce a perfect foam solution within the specification. When I complained about this case, my manager asked me to provide an opinion based on international standards. Is there guidance within NFPA-standards that can help me address this issue? Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe
5 Comments
MEDJBER AHCENE
12/31/2019 10:35:31 am
It is not a problem of compliance to any regulation. It is a technical matter that should be delt with the manufacturer of the bladder tank. Foam concentrate is a very corrosive product, it should not be in contact with the metal ( the tank surface ) . That 's why it should be contained inside the bladder which is in PVC material.
PETE
12/31/2019 10:46:41 am
The way that most AFFF bladder tanks I've dealt with are designed to operate is the foam concentrate is inside the bladder, and upon system activation water flows betwwen the bladder and tank wall forcing the concentrate out of the top. The concentrate is introduced to the water supply through a proportioner which is a side tap at the throat of a venturi orifice located on the system riser. Concentration is controlled by the diameter of the tap and the siphon force created by the differential pressure across the venturi converging diverging nozzle. Downstream of the proportioner is a test outlet with control valve NC and a bypass control valve NO. The standard is that the concentration is tested at various flow rates at the time of the installation prior to putting the system in service. I would contact ChemGuard or some other internationally recognized vendor that produces NFPA compliant systems.
Mike
12/31/2019 04:51:39 pm
Refer to NFPA 11.
Mike
1/3/2020 12:01:52 am
Can you provide the manufacturer's name and listing information? Leave a Reply. |
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