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Question for NFPA2001 Clause 1.5.1.5.3?

Question asked by zhangya on May 23, 2020

Dear, everyone! 

In the clause 1.5.1.5.3, it says if "design concentration exceeds that approved for use in normally occupied spaces ",we shall take FOUR measures(see below) when design, however, what is the specific approved concentration of normally occupied spaces for different agents, after I studied the section 1.5, is it the NOAEL or LOAEL? My comprehension is as fllows, am I  right? Or, can it be higher?

For Halocarbon Agents, 

The  approved concentration of normally occupied spaces is NOAEL, for example, it shoulb be use 9% for HFC-227ea.

For inert clean agents

The  approved concentration of normally occupied spaces is 43%.

Or, can it be little  higher? 

If we take the design concentration range of 9%~10.5%(HFC-227ea.) of Halocarbon Agents, or 43~52% of inert clean agent, must the FOUR measure be performed or not?

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Original clause of NFPA 2001:

1.5.1.5.3 For systems protecting occupiable enclosures or spaces where the clean agent design concentration exceeds that approved for use in normally occupied spaces (see Section 1.5), systems shall include the following:

(1) Supervised system lockout valves

(2) Pneumatic pre-discharge alarms

(3) Pneumatic time delays

(4) Warning signs

 

Does someone familar with this clause and can solve my question, thanks a lot!

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