Roland I think they took care of this by adding 175 psi relief valve on all wet systems now.
Bv Sent from my Motorola ATRIX™ 4G on AT&T -----Original message----- From: Roland Huggins <[email protected]> To: [email protected] Sent: Tue, Jul 31, 2012 15:15:01 GMT+00:00 Subject: Re: E x p a n s i o n T a n k s Water and Polypropylene has about the same degree of thermal expansion so I don't believe that is the reason. Although it hasn't really been discussed by the TC, the stated premise on SMALL antifreeze systems is that there is no trapped air. Conversely, we expect a lot of trapped air in a standard wet pipe system. Having said that, the corrosion driven efforts to reduce trapped air has NOT been correlated with the expansion concerns. Somewhere along the way, the two opposing efforts will bump heads. Roland On Jul 31, 2012, at 7:55 AM, Brad Casterline wrote: > the reason we do not need expansion tanks on wet systems is due to > water's > low coefficient of thermal expansion, but since it is not zero, and > assumed > potable, we use a 1/2" relief valve. why on grids but not trees?, > (until > 13-2013)-- because with an aux drain on the secondary main, most of > the air > (cushion) can be purged at system charge or recharge. now with the > emphasis > on getting the air out, best to use a relief valve on trees too. > this is my > understanding-- i might be mistaken. > > -----Original Message----- -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://fireball.firesprinkler.org/mailman/private/sprinklerforum/attachments/20120731/c6fadb5d/attachment.html> _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://fireball.firesprinkler.org/mailman/private/sprinklerforum/attachments/20120731/39ad8f40/attachment.html> _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum
