I would reply that every system that has a main drain has the ability to forward flow test the device. The question is does that reach the system demand, or even the operational range of the backflow device?
Take a 6" FEBCO 850 Horizontal installation. The system demand could be 600 or 800, but the first graph able point on FEBCO's pressure loss graph is 400 @ 3 psi. To get that out of a smooth bore 2" outlet it needs to have a pitot reading of 15 Psi. Doable? Is it the full forward flow? No but it is just as accurate as the full forward flow if all your verifying is a single point on the graph. What it won't prove is that the device will operate at full flow design. But I say there are no guarantees with any backflow test, that as soon as you record your results, that the device won't fail if you were to do it again. Also its a lot more likely to be done and recorded if all it take is running a main drain test and recording the residual pressure for that, and the drop across the device. 13.6.2.1.1 seems to support this somewhat, and 13.6.2.1.3 allows this where connections do not permit a full forward flow test of the system. This seems to be your condition, so test the pressure loss at the max flow you can, "Main drain test" and record your results. You've met the requirements of 25. Thom McMahon, SET Firetech, Inc. 2560 Copper Ridge Dr P.O. Box 882136 Steamboat Springs, CO 80488 Tel: 970-879-7952 Fax: 970-879-7926 -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Friday, September 19, 2008 4:22 PM To: [email protected] Subject: Re: forward flow testing NFPA 25 requires forward flow testing backflows. Yet many systems do not have provisions for this. Are the systems without these provisions exempt from the testing requirement? Forest Wilson Cherokee fire pro Sent from my Verizon Wireless BlackBerry -----Original Message----- From: "Travis Mack, SET" <[EMAIL PROTECTED]> Date: Thu, 18 Sep 2008 15:09:57 To: <[email protected]> Subject: RE: viscosities Ed: This system is entirely in the attic. The riser is the only portion that is in the heated space. I do these calculations in 2 parts. I calculate the system back to the interface of anti-freeze solution / water and get a pressure & flow demand at that point utilizing the DW calcs. I then do a second calculation using HW that is from the city supply to the interface point. It is basically how we used to do rack systems calculations. You calc the rack system and get a k-factor with pressure/flow demands. Plug that into the overhead system and there you go. In several people that I have talked to today about this, I am getting about 50/50 of saying to use each temp. It is pretty funny. I am still waiting on the AHJ. Hopefully, I can get a pretty decent concensus soon. -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Ed Kramer Sent: Thursday, September 18, 2008 2:43 PM To: [email protected] Subject: RE: viscosities Travis, This doesnt address your question, but I'm curious if the entire AF system is subject to outdoor temps (or just part of it). I ask, because if a significant part of the system is in a heated area, then it further complicates selecting an appropriate viscosity. My limited understanding of HydraCalc is that a single viscosity and a single density is entered for the entire calc (if I'm wrong, someone please correct me). Do you use the high viscosity (extreme min temp), the medium viscosity (average min temp) or the low viscosity (room temp)? Obviously the room temp viscosity wouldn't be appropriate, but how's a designer to choose? As in your example, the selected viscosity can make a whale of a difference in system costs. I've yet to calc an AF system using Darcy-Weisbach, so I'm hoping someone can enlighten me. Ed Kramer Littleton, CO > Ok..another viscosity question. > > When using HydraCalc to calculate antifreeze systems using the Darcy > method, it asks for viscosities of solutions. I have a data sheet > with the viscosities at various concentrations and various > temperatures. My question is, do you use the average daily minimum > temperature for an area, or the extreme daily minimum for an area? > For this particular project, the difference is 40°F in the 2 > temperatures. With the average daily minimum temperature, the system works with the available pressure. > With the extreme daily minimum, the city supply is not even close. > There is a 100+ psi swing in the demands. > > So, do we go with average minimums, or extreme minimums? > > There is always the option to go to a dry system, but the increased > design areas and reduced c factor will also force a pump on this > project. An anti-freeze system at average daily minimum works without > a fire pump. > However, we don't want to design/install an inadequate system. > > > Please feel free to call if you have any questions or comments. > > Travis Mack, SET > MFP Design, LLC > 2508 E Lodgepole Dr > Gilbert, AZ 85298 > 480-505-9271 > [EMAIL PROTECTED] > _______________________________________________ Sprinklerforum mailing list http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: [EMAIL PROTECTED] To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field) __________ NOD32 3453 (20080918) Information__________ This message was checked by NOD32 antivirus system. http://www.eset.com _______________________________________________ Sprinklerforum mailing list http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: [EMAIL PROTECTED] To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field) _______________________________________________ Sprinklerforum mailing list http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: [EMAIL PROTECTED] To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field)
