Positive Alarm Sequence, Fire alarm systems

[Sam@CEgeeks]

Good afternoon! I have (2) questions that I was hoping I could get some input on..

1. Does the NFPA 72 allow including an alarm verification window of (60) seconds to be included in the total (180) seconds of a positive alarm sequence?

2. Is there any exception that would allow a system to not enter into public mode when (2) devices were activated? An example would be a single detector in alarm then a manual pull station pulled..

Maybe this is the wrong section to place these questions in?

Thank you in advance!!:happysad:

 

[gadfly56]

Good afternoon! I have (2) questions that I was hoping I could get some input on..

1. Does the NFPA 72 allow including an alarm verification window of (60) seconds to be included in the total (180) seconds of a positive alarm sequence?

2. Is there any exception that would allow a system to not enter into public mode when (2) devices were activated? An example would be a single detector in alarm then a manual pull station pulled..

Maybe this is the wrong section to place these questions in?

Thank you in advance!!:happysad:

1. Unlikely. Alarm verification is an automatic feature and requires no human action. In this case, you would get 60 seconds plus the 180 seconds of the PAS. That's not the intent of the PAS. I suppose you could subtract the 60 seconds from the 180, but that would leave you only 2 minutes to check the alarm. You'd better hope Usain Bolt is on staff.

2. No, there are no exceptions.

 

[goldstar]

Would you please explain your interpretation of a Positive Alarm Sequence ?

I haven't worked on FA systems in a very long time so pardon my ignorance. From what I remember there were situations where public activation of a FA might cause panic. Let me use the Port of Authority Bus Terminal in NYC as an example. At one time there were coded manual fire stations made by Acme throughout the terminal. Although today these manual stations are considered antiques they served a well designed purpose at the time. These were shunt, non-interfering coded manual stations. If an alarm were activated from one of these stations it would ring in a designated area where authorized personnel were summoned to investigate its authenticity. If it were, in fact, a real alarm an authorized person could re-activate the alarm from any manual station using a special key that would allow the FA to be broadcast throughout the facility and also contact the FDNY.

In a case like this I'm not sure 2 minutes would be enough time to investigate the alarm, but I could be wrong.

 

[gadfly56]

Would you please explain your interpretation of a Positive Alarm Sequence ?

I haven't worked on FA systems in a very long time so pardon my ignorance. From what I remember there were situations where public activation of a FA might cause panic. Let me use the Port of Authority Bus Terminal in NYC as an example. At one time there were coded manual fire stations made by Acme throughout the terminal. Although today these manual stations are considered antiques they served a well designed purpose at the time. These were shunt, non-interfering coded manual stations. If an alarm were activated from one of these stations it would ring in a designated area where authorized personnel were summoned to investigate its authenticity. If it were, in fact, a real alarm an authorized person could re-activate the alarm from any manual station using a special key that would allow the FA to be broadcast throughout the facility and also contact the FDNY.

In a case like this I'm not sure 2 minutes would be enough time to investigate the alarm, but I could be wrong.

PA is totally screwed up, as they use a bastardized sequence thought up by some genius in NYC that is enshrined in Appendix Q. They have event and non-event mode for places of assembly that just don't work for, well, bus terminals. Or replacement terminals at, say, LaGuardia Airport.

 

[Sam@CEgeeks]

Positive Alarm Sequence, Fire alarm systems

Yes this is an issue that I am running into..

It's actually on an amusement ride (Can't tell you which one sorry)..

The design engineer is doing some funky stuff with the sequence of operations. Not only are they using positive alarm sequence, but now they have single detectors with alarm verification. Tested the facility last week, and the PAS doesn't start until after the 60 second alarm verification period.

I am trying to respectfully let the appropriate people realize that some things are incorrect and need to be addresses. Just trying to make sure that there are no exceptions to the rules here, even for special amusement rides.

 

[Sam@CEgeeks]

PAS Explanation

PAS Explanation

Here's the section regarding PAS, 2013 NFPA 72.. Just for reference

23.8.1.3.1.1 The positive alarm sequence operation shall comply with the following:

(1) To initiate the positive alarm sequence operation, the signal from an automatic fire detection device selected for positive alarm sequence operation shall be acknowledged at the fire alarm control unit by trained personnel within 15 seconds of annunciation.
(2) If the signal is not acknowledged within 15 seconds, notification signals in accordance with the building evacuation or relocation plan and remote signals shall be automatically and immediately activated.
(3) If the positive alarm sequence operation is initiated in accordance with 23.8.1.3.1.1(1), trained personnel shall have an alarm investigation phase of up to 180 seconds to evaluate the fire condition and reset the system.
(4) If the system is not reset during the alarm investigation phase, notification signals in accordance with the building evacuation or relocation plan and remote signals shall be automatically and immediately activated.
(5) If a second automatic fire detector selected for positive alarm sequence is actuated during the alarm investigation phase, notification signals in accordance with the building evacuation or relocation plan and remote signals shall be automatically and immediately activated.
(6)*If any other fire alarm initiating device is actuated, notification signals in accordance with the building evacuation or relocation plan and remote signals shall be automatically and immediately activated.