There is a section in NFPA that tells you when you need to use a return bend and when you do not. NFPA 13 7.2.2.
I don’t see a reason why it would not be allowed to come directly out the bottom of a 4” main, if you are otherwise allowed to come directly out the bottom of a branch line. There is an issue with connecting to an elbow, due to an interference fit issue (I’m sure you’re aware of that). And there may be an issue with connecting to a weld-o-let if it is coming off of a small branch line, also due to clearance. But if there is enough room for it to operate properly in a 1” threaded tee (most common arrangement) then of course there is plenty of room for operation in a weld-o-let on a 4” main, right? It might be worth a discussion with the manufacturer if the cut sheet isn’t clear and you really want to be sure. But, just like with the figures/pictures in NFPA 13, it is not right to assume that something is prohibited just because there isn’t a picture that exactly matches your installation scenario. That is way too conservative. -Kyle M From: Sprinklerforum [mailto:sprinklerforum-boun...@lists.firesprinkler.org] On Behalf Of John Denhardt Sent: Friday, January 18, 2019 6:51 AM To: sprinklerforum@lists.firesprinkler.org Subject: [EXTERNAL] Re: Dry pendent heads Look at the data sheet for the dry sprinkler you are using. Most likely this arrangement will not be allowed. This is a manufacture driven requirement. John August Denhardt, P.E. Strickland Fire Protection On Jan 18, 2019, at 8:47 AM, Richard Carr <rich...@diboco.com<mailto:rich...@diboco.com>> wrote: You may be required to use return bends, look at NFPA 13, 7.2.2 for direction. Richard M. Carr, SET Project Manager/Design Diboco Fire Sprinklers, Inc. 325 Jackson Loop Road Flat Rock, NC 28731 rich...@diboco.com<mailto:rich...@diboco.com> 828-696-3400 828-696-2288 Fax 828-708-9118 Mobile <image002.jpg> <image003.png> From: Sprinklerforum <sprinklerforum-boun...@lists.firesprinkler.org<mailto:sprinklerforum-boun...@lists.firesprinkler.org>> On Behalf Of John O'Connor Sent: Friday, January 18, 2019 8:21 AM To: sprinklerforum@lists.firesprinkler.org<mailto:sprinklerforum@lists.firesprinkler.org> Subject: Dry pendent heads Is there a prohibition anywhere in NFPA-13 to connecting a dry pendent sprinkler directly into the bottom of a dry pipe feed-main or cross-main 4” or larger, via a standard 1” weld-o-let? Thanks to you all. John R. O’Connor, SET, RME National Fire Sprinklers, Inc. 2601 Elm Hill Pike, Suite J Nashville TN 37214 Office 615-885-1301 Fax 615-885-7505 Cell 615-519-1118 jocon...@nfspk.com<mailto:jocon...@nfspk.com> <image004.png> In God We Trust _______________________________________________ Sprinklerforum mailing list Sprinklerforum@lists.firesprinkler.org<mailto:Sprinklerforum@lists.firesprinkler.org> http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org<https://urldefense.proofpoint.com/v2/url?u=http-3A__lists.firesprinkler.org_listinfo.cgi_sprinklerforum-2Dfiresprinkler.org&d=DwMGaQ&c=wn3mZQLIuInh2ClcJ0_DIA&r=Z_2A85VL7AQzoqudh6uOyS3bn8etxB7nLN8OBJwQd9A&m=ysOUtQkA2hObKoGADSBfrVqkpTm1PLHtoItkU0WE2ec&s=pTGL94UtFiEMb-4v415XnsSU1hBZW7mur09lAZrujcM&e=>
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