We're looking at a fire protection system, Ordinary Hazard Group 2, that requires primary fire protection water from a storage tank.
We are looking at three options, (1) above ground insulated with a heater, (2) underground concrete and (3) underground fiberglass. I am curious what the community here sees around the industry as being the most common choice here? The job site already has substantial excavation going on and the job is located in the north east so freezing is a concern. There will be no private hydrant so we don't see the need to carry hose allowance in our tanks sizing. Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe
9 Comments
Alex
3/31/2022 07:42:38 am
Hi,
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Glenn Berger
3/31/2022 08:09:40 am
Ground-level bolted steel tank with insulation and heater if required for that location.
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Jesse
3/31/2022 08:09:41 am
Texas here and we utilize above ground tanks almost exclusively unless there is a specific need for UG. We don't have the freeze risk you do, so clearly that's a large part of it.
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Jack G
3/31/2022 08:23:40 am
I ve installed about 200 tanks over 57 years. From 10 k to 500 k gallons. Also A custom tank, 22 diameter by 85 ft high, that no one would touch. FM approved installation.
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Mike M
3/31/2022 08:51:39 am
Underground tanks are typically only seen at what I would call high value facilities. The added costs of excavating, building, and typically using a vertical lift style pump are all significant. Most normal jobs are aboveground metal tanks with heat. But we're typically talking an ESFR or storage occupancy or multiple buildings, so your options at the OH II level may look different due to the smaller capacity. I would definitely price out multiple options and see what makes sense if you have time.
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David Toshio Williams
3/31/2022 09:08:27 am
Our frost depth is 6 feet here and we do some work on rural sites served by a well, so we need tanks. If at all possible I push for a fiberglass tank(s) located within the building foot print located under the fire pump room. Since the entire tank has to be below the frost line based on my reading of NFPA, the excavation cost (and allowable burial depth) is too high otherwise. I did have a sprinkler contractor VE to a concrete vault tank with a covering berm, but man is it ugly on a flat site. We have looked at in the building PE tanks, but the cost of the enclosed SF has usually been prohibitive. (Scott will probably mention that the MN Code allows high capacity wells to serve as a supply for a rural fire sprinkler system, but given the variability of well capacity, required large well diameter, hard rock in much of Minnesota, and the need to demonstrate flow every year, it seems like too much of a gamble.)
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Brad K
3/31/2022 10:55:39 am
Bolted Steel ground storage tanks are 95% of our sprinkler projects as the economical path. We just finished our first insulated bolted steel tank. We where presently supersized how well and quickly it came together with a tried and true tank vendor. Heaters seem fairly strait forward with a bolted flange(s). We haven't been involved with any long term service yet on these. Ask a lot of questions of the vender to help the und user anticipate future maintenance for this option.
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Chris Boyd
3/31/2022 12:46:40 pm
Would your AHJ consider foregoing the tank and connecting directly to a well provided it had a recent hydraulic analysis demonstrating sufficient flow ?
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David Toshio Williams
3/31/2022 01:43:24 pm
Noting my concerns above, even if allowable by the AHJ, to actually achieve the flow required for a fire protection sprinkler system. If you don't already have a well you really won't know what a well will produce until it's drilled... if the flow is not possible, then you have thrown your money down a hole! (And usually you have to prove flow every year... wells sometimes are not that consistent!)
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