Dear Mark My replies are as follows, which i have worked for one of the air base hanger in Middle east which was working to 9000 gpm as maxi demand approx. and decided to provide 4 x 3000 gpm pump sets with one as standby. Your case it seems to be smaller one which can be solved.
1 - Should the test header be sized to accommodate a 6000 gpm pump, or a 3000 gpm pump? The pump guy says that the common discharge header must be sized for the combined pumping capacity. The EOR states that it is only based on 1 pump flowing. I seem to agree with the pump guy, in that you need to test with both pumps flowing so you can test your water supply as well to show you can get the full 150% flow from the water supply. It is easy to size the piping so that the recommended velocities in NFPA 20 are not exceeded. It is just a question as to what is the basis. REPLY: As per NFPA 20, Each pump should have a test line with an isolation valve connected to a common test header connected back to the tank. The flow meters are meant for testing each pump flow at 0%,100% & 150%,Hence you can size the flow meter of 0-6000 gpm ( maximum 175% of flow of the pump as per NFPA), hence the test line from each pump will be tested separately as a part of annual/semi annual maintenance to comply the NFPA. Common test header from discharge line is not acceptable and mislead. 2 - Should the common discharge header that the pumps tie in to be sized based on 3000 gpm pump or 6000 gpm pump? I believe that the common piping (after the pump discharge valve) only needs to be sized based on hydraulic calculations. REPLY: Common discharge header to be sized to the maximum water demand requirement with hydraulic calculation only if the size of pump is not listed in NFPA, which will be the correct validation of the sizing the header. 3 - These are diesel pumps. The individual relief valves are tied into a common discharge header. How should this be sized? Based on 3000 or 6000 gpm pumps? REPLY: As per NFPA 20, each diesel engine driven pump should be sized based on the flow of individual pump and connected to a common discharge header sized to maximum water demand or equal to above point 2 discharge header size can be provided. Part of the issue is that NFPA 20 only goes to 5000 gpm tables for sizing pump room piping/equipment. The EOR is stating that the NICET tech is to correct anything in the pump room and provide it per NFPA 20. However, since we have a 6000 gpm total capacity, it is not possible to size things based on the summary table in NFPA 20 if it is to be based on 6000 gpm. REPLY: Who are EOR? Regards D RADHAKRISHNAN Senior Manager-Fire division NFPA member since 2011 and have 20 yrs experience in Fire fighting system in INDIA/UAE/QATAR/OMAN Mobile: 0971 050-1643785,[email protected] On Thu, Mar 26, 2015 at 11:25 PM, Travis Mack <[email protected]> wrote: > I am working on a project where there is a fairly large demand. The EOR > has determined there are to be (3) 3000 gpm pumps. These are all installed > parallel. One of the pumps is to be a backup pump. The design has not been > finalized, but the system demand (overhead sprinklers and grate foam > nozzles) is somewhere around 6000 gpm. That is why we have two 3000 gpm > pumps in parallel to create a 6000 gpm pumping capacity. There were some > errors in the EOR pump room design that led to a few other questions. We > are getting conflicting information from the EOR and the pump guys. The > arrangement is that the pumps share a common suction header and a common > discharge header. > > Per NFPA 20, a 3000 gpm pump needs a 12" discharge. The EOR showed 10" > discharge piping and equipment, so this is what flagged some questions with > the pump room design. The questions are now: > > 1 - Should the test header be sized to accommodate a 6000 gpm pump, or a > 3000 gpm pump? The pump guy says that the common discharge header must be > sized for the combined pumping capacity. The EOR states that it is only > based on 1 pump flowing. I seem to agree with the pump guy, in that you > need to test with both pumps flowing so you can test your water supply as > well to show you can get the full 150% flow from the water supply. It is > easy to size the piping so that the recommended velocities in NFPA 20 are > not exceeded. It is just a question as to what is the basis. > > 2 - Should the common discharge header that the pumps tie in to be sized > based on 3000 gpm pump or 6000 gpm pump? I believe that the common piping > (after the pump discharge valve) only needs to be sized based on hydraulic > calculations. > > 3 - These are diesel pumps. The individual relief valves are tied into a > common discharge header. How should this be sized? Based on 3000 or 6000 > gpm pumps? > > We are awaiting input from the authority having jurisdiction as well on > this topic. The biggest issue is the pump test header and relief valve > discharge piping. There are more issues of now trying to fit 12" > valves/pipe/fittings on the discharge side of a pump in a room that was > tight to begin with and was designed for 10" discharge equipment. > > Part of the issue is that NFPA 20 only goes to 5000 gpm tables for sizing > pump room piping/equipment. The EOR is stating that the NICET tech is to > correct anything in the pump room and provide it per NFPA 20. However, > since we have a 6000 gpm total capacity, it is not possible to size things > based on the summary table in NFPA 20 if it is to be based on 6000 gpm. > > I am just interested as to the thoughts of the guys on this forum. > > -- > Travis Mack, SET > MFP Design, LLC > 2508 E Lodgepole Drive > Gilbert, AZ 85298 > 480-505-9271 > fax: 866-430-6107 > email:[email protected] > > http://www.mfpdesign.com > https://www.facebook.com/pages/MFP-Design-LLC/92218417692 > Send large files to us via: https://www.hightail.com/u/MFPDesign > > _______________________________________________ > 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
