I guess it's too late to take the dry off city only, before the pump-- (usually in this set-up, the parking goes down and the high rise goes up)-- If 20 ft/sec was spec'd, city water only might not have been utilized-- I can see 50 pound safety on HUGE dry systems, AND the xtra heavy DP dilemma.
-----Original Message----- From: David de Vries [mailto:[email protected]] Sent: Friday, November 12, 2010 5:56 PM To: [email protected] Subject: RE: High Pressure Dry Pendents Sure, I have seen a fair number of popped circuit breakers, switches shut off, etc. and the air compressor is off, but this is a high rise building with all the bells and whistles. Fire alarm panel will be monitored by the complex and by the municipal remote station. If there is a low air alarm (yes, I have seen those fail also), people will know. That said, I am still not comfortable allowing the 175 sprinklers in a system that will see about 215 when it trips. Considering all options, including running exposed piping with high pressure uprights in the finished ceiling area (architect throws fit here), install a PRV ahead of the DPV (contractor throws fit here), separating and heating the finished ceiling areas and use high pressure pendents on return bends (everyone who has to come up with money throws fit here), etc. Dave David A. de Vries, P.E., CSP Firetech Engineering Incorporated --- On Fri, 11/12/10, Chris Cahill <[email protected]> wrote: From: Chris Cahill <[email protected]> Subject: RE: High Pressure Dry Pendents To: [email protected] Date: Friday, November 12, 2010, 7:50 AM With your subrogation work do you really believe supervised low air protects against false trips. Sometimes yes sometimes no IMHO. How about the one where the alarm rang for days before the freezer tripped and we got to take the sprinkler system to the parking lot for a couple days. Or sometimes the air compressor runs nearly constantly from a larger leak masking the leak and finally fails only then revealing the leak before anyone has a real chance to react to the low air alarm before it trips. But I think we digressed. I wouldn't allow the head if involved. Just not worth the risk IMHO. I though agree it would probably work. Good news is they only have to last 10 years. Chris -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of David de Vries Sent: Thursday, November 11, 2010 6:21 PM To: [email protected] Subject: RE: High Pressure Dry Pendents Chris, we are designing to avoid the false trip from a dead compressor (supervised low air), but maybe a little hammer from the fire pump starting from a dead jockey pump will trip the DPV. Then you are right; we get the full static pressure. Dave David A. de Vries, P.E., CSP Firetech Engineering Incorporated 2715 Harrison St. Evanston, IL 60201 Tel: 847-733-0944 Fax: 847-866-6255 _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.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 [email protected] http://fireball.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 [email protected] http://fireball.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)
