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How do you calculate a flow and pressure rate from a gravity tank and a pressure tank?
Is there a requirement for periodic testing of flows from these devices similar to that of a fire hydrant? In some instances, high rise buildings in NYC have just a gravity or a pressure tank for the water supply and I am trying to figure out out to measure what type of flow and pressure is available when these are considered a primary water supply for their sprinkler system. Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe
4 Comments
Casey Milhorn
10/27/2023 08:56:03 am
If only a gravity tank, take your elevation gain and multiply by .433 psi. Once you have pressure, you can find flow by using the Q=K * sqrt of P formula. Quantity being flow, K being relative to your sprinkler/opening size, and pressure being static pressure.
Streeter Stirling
10/27/2023 10:00:43 am
To add on, if it is an actual pressure tank, you would do what Casey has said above but start at what the tank's static pressure is at, and the add the pressure from elevation to that, instead of starting at 0 psi and just calculating pressure gain from elevation.
David Rey Castaneda
10/31/2023 11:51:07 am
You can use .434 X height to obtain PSI. Also, given the height of the elevated water tank, you can use height divided by 2.31=PSI.
Anthony
10/30/2023 08:32:52 am
The static should be easy as other have shown. Determining the residual flow and pressure can be challenging without a flow test. Make sure you understand the flow rate through the exiting orifice of the tank. If you're not familiar with how to do this theoretically then get a flow test from the outlet of the tank or a near by riser. Also, your flow test needs to take into account the level of the tank after 30~60 min of flow, because that is the level of the tank after the required duration is met. that tank level will have a lower level and thus lower static and residual pressure. Leave a Reply. |
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