Gas Suppression System Time Delay 1

[Pgee630]

Anyone have experience designing / installing a gas suppression system with a gas discharge time delay of > 30s. My understanding from NFPA is that the time delay should be sufficient for evacuation, but not definitely 30s. However, in some authorities, it's stated in their code that the time delay should not be > 30s.

 

[cdafd]

Usually there is a count down

Check manufacture specs

How are you involved in process? Owner, designer, fire alarm, other ???

Will look at 2001 to see what it says

 

[cdafd]

4.3.5.6.1 NFPA 2001, 2018 Edition
For clean agent extinguishing systems, a pre-discharge alarm and time delay, sufficient to allow personnel evacuation prior to discharge, shall be provided.
4.3.5.6.1 & 4.3.5.6.3 NFPA 2001, 2018 Edition
Time delays shall be used only for personnel evacuation or to prepare the hazard area for discharge. Time delays shall not be used as a means of confirming operation of a detection device before automatic actuation occurs.
Typical stages of operation:
 General Alarm – One detector activated
 Pre-discharge – Two detectors activated, starts pre-
discharge time delay
 Release – System discharges after pre-discharge time
delay expires

 

[cdafd]

Pgee630


What do you feel it should be??

1-30?

Or zero

 

[Pgee630]

It only says sufficient to allow personnel evacuation prior to discharge, but not really specifying how many seconds.

 

[cdafd]

So what number do you want to go with?


Are you designing, owner or what?

 

[Pgee630]

60s

 

[UFT12]

If you have valid arguments why 60 sec are necessary then your AHJ should evaluate the situation and at the end why not accept it. Say for example a process system in a industrial occupancy where life safety criteria do not apply (normally unmanned), you could go higher to 60 sec provided related technicalities do not allow for faster shut down. It also depended on what is the FF plant/concept of the facility. Is there a local fire department or if not, how soon is the municipal fire department going to need to reach the premises?

 

[stookeyfpe]

Have you calculated the egress time? That's a more reasonable approach.