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NFPA 11

Question asked by chong on Sep 20, 2020

According to NFPA 11 testing of Balanced Pressure Proportional System (BPPS) is possible with water instead of actual foam concentrate.

 

What are the requirements and criteria for the testing of BPPS System with Foam Pump and Water?

 

Is there and conditions that we should take into account that :-

1) Testing with water only possible for Newtonian foam concentrates like AFFF. Water test method not to be conducted for non-Newtonian foam concentrates like alcohol resistant ones (AR-AFFF) or fluorine-free ones.

2) NFPA 11 requires the initial acceptance test to be conducted with actual foam concentrate. The exact same test setup must be used for the subsequent test during the acceptance test with water. This setup represents the base condition for all tests with water in the future where the same test conditions have to be established (pressure, flow rate, etc.).

3) Accordingly, testing the BPPS with water requires comprehensive measurement equipment as well as intense training and education of personnel or alternately hiring a third party (service company) which offers the required test equipment and appropriately qualified staff.

 

According to NFPA 11 and NFPA 20 all foam pumps must be able of running dry for 10 minutes. Progressive cavity pumps cannot run dry and special dry run protection should be installed. 

 

a) Is it recommended to monitor the level of the foam concentrate tanks by means of a level gauge with alarm contacts (High and Low) and / or to transfer an appropriate signal to the Main Fire Alarm control system for appropriate action?

b) NFPA specifies required minimum extinguishing times in dependence of the type of liquid and type of protected area / devices. Based on that and the stored foam concentrate, it can be calculated after which time period the foam concentrate in the tank will be exhausted.

c) Are there any procedures as per NFPA 11 how to proceed in the case the fire does exceed this extinguishing time?

d) The effect of dry running for the foam proportioning system will caused a significant rise of temperature as there is no liquid present for cooling.

e) There is no internal protecting device installed in Foam proportioning systems.

f) What are the measures to be taken to avoid this?

 

Appreciate your confirmation.

 

Best Regards,

 

Chong Y.K

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