http://www.nfpa.org/~/media/Files/Research/Research%20Foundation/foundation% 20proceedings/elliott2.pdf
Good show Duane. I like the results of actual measurements you show, whether they relate to real life or not :) I actually thought Tony was worried about popping a head by shining light on it because it was QUICK RESPONSE -----Original Message----- From: Johnson, Duane (NIH/OD/ORS) [C] [mailto:[email protected]] Sent: Tuesday, March 25, 2014 2:23 PM To: [email protected] Subject: RE: Quick response Tony (and others), Quick response is supposed to refer to the sensitivity of the sprinkler element, not the response time to a fire. There are many factors that must be considered when estimating response time (ie the fixed temperature setting of the sprinkler has some have already noted). Other factors include fire size, ceiling height, sprinkler spacing, etc., even ambient temperature. There are many concepts to analyze to answer your question, which is why everyone is saying it depends. There are two factors I wanted to touch on: heat transfer and RTI. First, the temperature must be raised high enough to reach the activation temperature of the sprinkler, ie 155°F. There are three basic ways to transfer heat to the sprinkler: convection (ie, blowing hot gases across the sprinkler), conduction (ie, touching something hot to the sprinkler), radiative energy (ie, UV rays). At least in the initial phases of a fire, heat is transferred to a sprinkler primarily through convection. Similarly, a spot light could potentially have enough convection to activate a sprinkler, if, the light produces enough heat (need large wattage), the light is close enough to transfer the heat, and the light is held on the sprinkler long enough for the sprinkler to heat up. Which leads into the second topic, RTI. As a side note, radiant energy plays a major factor given time. Way back when I was turning wrenches in the AZ summers, I just finished taping a box of 155°F sprinklers. Note, the temperature outside was only 105°F to 110°F. I pushed the sprinklers under the tripod (protective covers weren't invented yet!). When I returned a few hours later, I discovered the sun had shifted and the shade was no longer over the box of sprinklers. Every last one of the sprinklers had popped! Little did I know at the time, but this is when I learned radiative energy plays an important part of heat transfer. After all, it was NOT 155°F outside. RTI, response time index, this is a measure of how quick or slow the thermal lag of the sprinkler is. Note, a sprinkler will not instantaneously activate as soon as the surrounding temperature reaches an activation temperature, ie 155°F. There will be a time lag before the sprinkler activates. The maker of the sprinkler bulbs, Job, used to show this at the AFSA convention! Large bulky sprinklers will take longer to heat up (like a cast iron pot on a stove) and activate, whereas, smaller sprinklers, or smaller thermal elements such as a 3mm glass bulb, will heat up quicker (like an aluminum pot on a stove). So a sprinkler with a smaller RTI will activate quick than that of a sprinkler with a larger RTI...if the activation temperature is the same. My son did a science fair project (I highly recommend this project to all you sprinkler Dads) a few years back by timing the activation of a sprinkler head after turning on a heat gun which was putting out a few hundred °F (don't remember exact temp). The heat gun was about a foot away from the sprinkler, see results below. As you will see, the response element and the fixed temperature each have an effect on the response time. I might as well say it now, these times are not representative of response times you will see in a fire scenario...response time depends on other factors... 1951, 165°F, standard response, link 20.3 sec 1977, 165°F, standard response, link 20.5 sec 1987, 165°F, standard response, link 17.1 sec 2007, 155°F, standard response , glass bulb 21.7 sec 2006, 155°F, quick response, glass bulb 7.6 sec 2003, 135°F, standard response, glass bulb 14.2 sec 2002, 175°F, quick response, glass bulb 8.8 sec 2007, 200°F, quick response, glass bulb 10.0 sec For the technically curious... Sprinklers defined as fast response have a thermal element with an RTI of 50 (meters-seconds)1/2 or less. Sprinklers defined as standard response have a thermal element with an RTI of 80 (meters-seconds)1/2 or more. (See A.3.6.1) For the super technically curious (Brad?)... For modeling purposes, concealed sprinklers can be considered equivalent to pendent sprinklers having a similar thermal response sensitivity installed 12 in. (305 mm) below smooth unobstructed ceilings, and recessed sprinklers can be considered equivalent to pendent sprinklers having a similar thermal response sensitivity installed 8 in. (203 mm) below smooth unobstructed ceilings. (See A.3.6.1) Duane Johnson, PE Program Manager Division of the Fire Marshal (Contractor) Office of Research Services National Institutes of Health 301-496-0487 "Protecting Science - One Sprinkler at a Time" -----Original Message----- From: Tony Palmero [mailto:[email protected]] Sent: Saturday, March 22, 2014 6:52 PM To: [email protected] Subject: Re: Quick response Brad, WTF? What does a skylight have to do with it if the light would have to be touching the sprinkler to set it off? Is there a rule in NFPA 13 for this kind of stuff? I just want to get pipe in the air and do it right. Theoretically speakin'. Tony On Sat, Mar 22, 2014 at 5:34 PM, Brad Casterline <[email protected]>wrote: > We do have to use higher temp heads in skylights though so I am wrong! > Don't shine it on the sprinklers or the kids too long at a time! > > > On Mar 22, 2014, at 5:25 PM, Brad Casterline > > <[email protected]> > wrote: > > > > I think the light would have to be almost touching the element to > > set it > off (conduction). Response Time Index is a measure of the temp AND > velocity of the air (convection). The energy of the light itself drops > like a rock > (^4) with distance from the source. (the radiative component). > > Of course I could be wrong Tony, and often am :). > > > > > >> On Mar 22, 2014, at 4:50 PM, Tony Palmero <[email protected]> > wrote: > >> > >> Brad, > >> > >> I was wondering if lights could send enough heat to a element to > >> make > it go > >> off. I run the spotlight at school plays at my kid's school and > >> was > just > >> thinkin' about it. > >> > >> You guys on the forum are great. I don't think any of this stuff > matters > >> to me putting pipe in the air, but it is fascinating. > >> > >> Tony Palmero > >> > >> > >> On Sat, Mar 22, 2014 at 4:45 PM, Brad Casterline < > [email protected]>wrote: > >> > >>> It depends on how fast the heated air is moving across it, which > depends > >>> on fire size and ceiling height. But this is true for standard > >>> response also. May I ask why you ask? > >>> > >>>>> On Mar 22, 2014, at 4:27 PM, Tony Palmero > >>>>> <[email protected]> > >>>> wrote: > >>>> > >>>> How quick is a qwik resp sprinler? > >>>> _______________________________________________ > >>>> Sprinklerforum mailing list > >>>> [email protected] > >>> > http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkl > er.org > >>> _______________________________________________ > >>> Sprinklerforum mailing list > >>> [email protected] > >>> > >>> > http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkl > er.org > >> _______________________________________________ > >> Sprinklerforum mailing list > >> [email protected] > >> > http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkl > er.org > > _______________________________________________ > > Sprinklerforum mailing list > > [email protected] > > > http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkl > er.org _______________________________________________ > Sprinklerforum mailing list > [email protected] > > http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkl > er.org > _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org
