Brad, I'll take that as a compliment. Mark at Aero 602 820-7894 -----Original Message----- From: Sprinklerforum [mailto:[email protected]] On Behalf Of [email protected] Sent: Wednesday, August 16, 2017 6:52 AM To: [email protected] Subject: [EXTERNAL] Re: Jet/impulse fans
I could sit and talk with you about this until the cows come home Nicky but I don't want Roland to have to 'make that face' at me ever again. (lol mphelps). So I'll just say I have the experience (10 yrs) and the software (exactly as referenced in your bottom link) necessary to address all your bullet point concerns, and, eventually, answer all your questions, to a degree of accuracy currently considered to be state of the art. If you or anyone reading this wants to take it off Forum please feel free to mail me at: [email protected] Thanks for another excellent post- you have already planted about half the model in my head. Brad Open Noon to Midnight in Kansas :) Quoting Nicky Marshall <[email protected]>: > On these projects, the fans are used for normal exhaust only. They > are to shut down on fire (sprinkler or alarm manual call point.) We > have found a document which highlights the concerns, which we agree > are valid concerns to have: > • Disturb the smoke layer > • Spread smoke > • Affect sprinkler operation > • Fan the fire > • Activate wrong sprinkler heads > • Spread fire to adjacent cars > • CO generated during the fire will cause jet fans to increase flow > output (where applicable) > > But are they just perceived or are they real? Is the extent of the > impact actually significant and much worse than a traditional HVAC > ducted system? > > For those of you who like numbers: > One building carpark, 37 x 23m (120 x 75 ft), has 1 supply/make-up air > fan 2050 L/s and 2 Jet fans at low speed - 12N thrust. 2.6 air > changes per hour. > - HVAC Modelling shows velocity at chest height (for purposes of > breathable air quality) as typically being less than 1.5m/s (5 > ft/sec). it does not appear to exceed 3 m/s. > 4 other building carparks (typical), 35 x 18m (115 x 60 ft) have > natural ventilation with one inlet grille and one exit grille, plus > one low speed Jet fan. No air changes calculated with natural > ventilation. > - HVAC Modelling shows velocity at chest height (for purposes of > breathable air quality) as typically being less than 1 m/s (3.3 > ft/sec). it does not appear to exceed 2 m/s. > I have asked if it is possible to produce velocity information at > sprinkler height... > > Spending NZ$15-$20,000 on aspirating detection for each building seems > excessive if the effects of the jet fans are not significant. > Is an on-board/duct detector adequate? Or is it prone to false alarm > and shut down when it should be operating to keep air quality safe? > > Nicky Marshall > Southern Regional Manager > PROTECH DESIGN LIMITED > Specialist Fire Protection Consultants > Phone: +64 (0)3 579 5577 extn 2 Mobile: +64 (0)21 433 488 Email: > [email protected] Skype: nicky-marshall Web > :www.protechdesign.co.nz Address:105A Alabama Rd, Redwoodtown, > Blenheim 7201, NZ Postal: PO Box 4022, Redwood Village, Blenheim 7242, > NZ > > “I always wondered why somebody doesn't do something about that. > Then I realised I was somebody” Lily Tomlin > > -----Original Message----- > From: [email protected] [mailto:[email protected]] > Sent: Tuesday, 15 August 2017 12:32 PM > To: [email protected] > Subject: Re: Jet/impulse fans > > I will check your links tomorrow Nicky- they look interesting. > I've worked on several systems in Qatar. Qatar Civil Defense has very > detailed requirements for fire modeling these systems, and negative > impact on sprinkler activation is not mentioned. These small impulse > fans direct the car exhaust toward the huge exhaust shafts as part of > normal operation--- they have two speeds-- normal and emergency. The > 10m/s is the emergency speed. If a signal from a flow switch is used > kick them to emergency speed, the sprinklers already activated. > > Brad > > Quoting Nicky Marshall <[email protected]>: > >> Are Jet/impulse fans installed in basement carparks a serious >> concern to the successful operation of sprinklers? >> >> Example of the fans: >> http://www.fantech.com.au/FanRange.aspx?AppID=P2&RangeID=2021 which >> also discusses some installation recommendations with regards to >> sprinklers. >> >> We are starting to see more of these installed in basement carparks >> as a cheaper option to ducted systems. >> The velocity is around 10 m/s (32 ft/sec) at the fan discharge point. >> But 1-2 m/s at chest height over car park areas. >> Obviously this impacts air and heat movement and sprinkler operation. >> But if they are installed in drive lanes only (where there is no fire >> load) and shut down as soon as one sprinkler operates, is the risk >> largely mitigated? >> FM Global data sheets only discuss air velocities for storage >> sprinklers. It appears to be silent for non-storage sprinklers. >> I cannot find anything in NFPA 13. >> New South Wales Australia, the Fire Service are asking for additional >> smoke detection to shut the fans down (unless fire modelling shows it >> is acceptable). Is this really necessary? >> https://www.fire.nsw.gov.au/gallery/files/pdf/guidelines/impulse_fans >> _ in_carparks.pdf There was also a case study done based on fire >> modelling. >> http://www.sciencedirect.com/science/article/pii/S2214398X13000034 , >> but every building and system is different... >> >> We agree that it needs to be considered, but are unsure that an >> additional detection system is necessary. >> Your thoughts and input appreciated. >> >> Nicky Marshall >> Southern Regional Manager >> PROTECH DESIGN LIMITED >> Specialist Fire Protection Consultants >> Phone: +64 (0)3 579 5577 extn 2 Mobile: +64 (0)21 433 488 Email: >> [email protected] Skype: nicky-marshall Web >> :www.protechdesign.co.nz Address:105A Alabama Rd, Redwoodtown, >> Blenheim 7201, NZ Postal: PO Box 4022, Redwood Village, Blenheim >> 7242, NZ >> >> "I always wondered why somebody doesn't do something about that. >> Then I realised I was somebody" Lily Tomlin >> _______________________________________________ >> Sprinklerforum mailing list >> [email protected] >> http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprink >> l >> 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
