[Sprinklerforum] Re: Double Interlock Pre-Action Systems

Tue, 24 Sep 2024 07:35:24 -0700

Kyle,

What Craig said.

There is no text in -13 or -72 of which I'm aware that specifies time requirements for electrical detection to send a signal to the releasing panel, or that it must be received by that panel prior to the fire sprinkler operating.  Additionally, there is no text I'm aware of which specifies a sequence of which detection has to occur first. 

There may indeed be a built-in delay in the LHD.  Is it listed for use in support of a preaction fire sprinkler system?

sincerely,
Ken Wagoner, SET
Parsley Consulting
500 West Mechanic Street
Harrisonville, Missouri 64701-2235
Phone: (760) 745-6181
Visit the website

 



On 9/24/2024 8:37 AM, Prahl, Craig wrote:

In a DIPA system you HAVE to have both a sprinkler open and a detection device go into alarm.  It doesn’t matter in what order that would occur.  The DIPA system is more for prevention of discharge until it’s glaringly obvious that a fire is in progress.  Typical for freezers, Data Centers, sometimes electrical rooms when the sparky guys are really paranoid,  etc.    

 

So, if the Linear Heat Detection (LHD) goes into alarm, it will transmit a signal to the DIPA releasing panel but nothing more is going to happen until a sprinkler opens.  Only when the LHD is in alarm AND a sprinkler opens is the PA valve going to open, 

 

Any delay in the LHD signal is not going to be of any great relevance if the system is operating properly.  There is no calculation or specified time frame in any code or Standard. 

 

Craig Prahl | Jacobs | Fire Protection SME – Special Hazards | [email protected] | www.jacobs.com

1041 East Butler Road   Greenville, South Carolina  29606

CONTACT BY: Phone 1-864-676-5252, Email or MS TEAMS

 

 

From: Kyle.Montgomery <[email protected]>
Sent: Monday, September 23, 2024 7:48 PM
To: [email protected]
Subject: [EXTERNAL] [Sprinklerforum] Re: Double Interlock Pre-Action Systems

 

I guess what I’m really asking is what is the difference in response time for linear heat detection versus my sprinkler heads? In this case, it’s protecting cold storage, so it’s a standard-response, high-temperature sprinkler.

 

-Kyle M

 

From: Kyle.Montgomery
Sent: Monday, September 23, 2024 4:45 PM
To: [email protected]
Subject: Double Interlock Pre-Action Systems

 

It’s my understanding that the premise behind double interlock pre-action systems is that they should be designed in such a way that, in the event of a fire, the detection (heat detector, flame detector, smoke detector, linear heat detection, etc.) should activate before a sprinkler head activates. Is there any formula or rule of thumb about how long the detection should take to activate versus how long the sprinkler should take to activate?

 

I’m working on a project and the alarm guy is telling me that there is a built-in activation delay in the releasing panel between when the linear heat detection sends a signal and when the releasing panel activates the solenoid valve. Is that normal? I’m wondering if that delay will actually delay the activation time of my pre-action valve, or if the delay is short enough that it is less than the normal time delta between linear heat detection activation and sprinkler head activation.

 

For example, if the built-in delay in the releasing panel is 15 seconds, but the delta between LHD activation and sprinkler head activation is normally more than 15 second, then there wouldn’t be any tangible delay in the activation (opening) of the pre-action valve.

 

Kyle Montgomery

 

Aero Automatic Sprinkler Co.

21605 N. Central Ave.

Phoenix, AZ 85024

Direct: 623.580.7820

Cell: 602.763.4736

[email protected]

 



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