I have a question with regards to the ESFR dry pendent 'box-in-a-box' freezer installation.
How do you handle the large ceiling-hung condensing units that are present in basically every large cold storage freezer/cooler?
Do you provide some kind of a supplemental system below the units?
I see that the new antifreeze solutions are listed for storage occupancies, but specifically exclude ESFR systems.
We have a large cold storage freezer where the mechanical consultant has specified ESFR dry pendents, but provided no direction on how to address the condensing units. I'm sure I'm not the first to run into this issue, and I am curious how others have dealt with it. Thanks in advance.
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3/30/2021 09:22:59 am
Typically you must get the product data on the units and equipment layout being hung in the freezer and space the sprinklers around them treating them as large ceiling obstructions. Lights and other surface mounted obstructions will be an issue as well. I have not seen many instances where the condensing units are large enough to require additional protection below. Many of them are long (i.e. 4' to 8') but are usually 3'-6" or less wide thus not requiring protection below. If the unit meets the rules of 13 requiring sprinklers below I have seen a 1" sprinkler line penetrate the freezer and place a couple uprights below the unit and run the pipe behind the unit and provide a drum drip along the wall. The reason for the additional sprinklers below the large condenser units was because they had drip pans that were greater than 48" all around. That isn't the most ideal install but I don't think there was much else to do for the contractor. I'm interested if there is another way to skin the cat on this one.
3/30/2021 09:29:21 am
I forgot to mention that the sprinkler protection below the units with a drum drip obviously is only for a dry system. If you system is wet with dry ESFR's, and the obstructions are greater than 48" minimum req's per 13 then your only other option would be a ancillary system. Preferably dry, so that if the system discharges it dumps water and not antifreeze solution over any food products.
Brian Gerdwagen FPE
3/30/2021 09:34:07 am
Like any other ESFR you need to direct the Mechanical Engineer and contractor where to put the boxes based on the ESFR placement. There should be a No-Fly Zone plan and details on the sprinkler shop drawings that show where these obstructions are allowed and how they are allowed.
3/30/2021 09:46:45 am
I have done a lot of freezers recently with dry ESFR heads and we place the sprinklers on both sides of the unit no more than 5 ft from center. It is not 100% ESFR code compliant but FM and other AHJs have understood the situation and not required an auxiliary pre-action or dry system for just the under duct sprinklers.
4/5/2021 01:26:19 pm
I have done few projects where the sprinklers are not provided below these type of obstructions (large ducts or hanging units) and are accepted by the AHJ’s.
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