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JohnBoy1 (Electrical) (OP)
7 Jun 07 16:53
Can someone explain the difference between a flow test and a hydro test on a fire hydrant. I have a customer who asked to have the hydrants tested at a site, and looking back thru records I found that a company did flow testing for 8 hydrants for $225.00 each and the year before at the same site a company did hydro testing for $375.00 for all eight. Also, is the difference in this testing in NFPA 25, and is it required annually, or at all?
Helpful Member!  stookeyfpe (Specifier/Regulator)
7 Jun 07 18:00
The hydrostatic test is required by NFPA 24. It is only done at the initial installation, if repairs are made, or if the system is enlarged.

The flow test is required annually to ensure the hydrant is functional. If its done correctly, it also serves to confirm the availabilty of required fire flow.
Helpful Member!(2)  TravisMack (Mechanical)
8 Jun 07 8:38
Hydrostatic testing is exactly what it says.  You are testing with water that is not moving.  Basically, the system is pumped up to 200 psi, or system pressure +50 psi, whichever is greater.  You then monitor the pressure drop to determine any leaks.  As Stookey stated, this is only done at initial install, repairs, or modifications.

Flow testing is flowing water through the hydrants.  This will require at least 2 hydrants.  You put a gauge on one of the hydrants to take your static pressure.  You then open another hydrant for flow.  This hydrant should run a few moments to make sure debris has cleared.  You then place your pitot tube in the center of the stream and record the reading.  Before you shut down the hydrant, you need to record the residual pressure on the gauge hydrant.  Restore the hydrants to the original condition, closed with all caps on, and move to the next one.

Techinically, according to NFPA 291, you should open enough hydrants to get a pressure drop of 25%.  I have yet to see anyone do testing like this.

Per NFPA 25, hydrants shall be inspected/tested yearly.  Full flow tests of the underground piping is required on a 5yr schedule.  If you are going to be doing any of this testing, you should have a copy of NFPA 25 and someone trained in Inspection / Testing / Maintenance of Water Based Fire Protection Systems (BTW, that is the title of NFPA 25).
FFP1 (Mechanical)
12 Jun 07 16:50
I agree with everything stookeyfpe and TravisMack have posted, but I would like to add a few additional comments.

Most states require "certified" fire protection contractors or individuals who meet certain qualifications which are clearly outlined in state law for this type of testing (for good reasons if you want my opinion).

Based on the comments above, it looks like the company who charged $1,800 ($225 x 8 hydrants) took advantage of the ignorance of their customer. Based on NFPA 25, hydrant flow testing is required on a 5 year interval to test certain aspects of the underground mains. For a location which has 8 fire hydrants, this inspection activity can usually be completed with one or maybe two hydrant flow tests. The number of required hydrant flow tests primarily depends on the number of loops and design or layout of the underground main system.

If you are located in the great state of Georgia, we would be more than happy to provide all of the inspection and maintenance activities this customer needs to meet NFPA code. Based on your original comments, I would not trust the company you referenced to do what is best for their customers.
DavidCR (Mechanical)
3 Jul 07 18:37
A flow test may have different objetives and can be required by the AHJ or fire department to check if the water supply meets the folowing:

1. That the design flow and pressure requirements are met.
2. To compare the current flow conditions with a previous measurement.
3. To check if the hydrants meets the minimun flow and pressure for fire department use, private brigade or occupants hose use, or for the use of a hydrant with the fire engine. Also to check if the pressure donĀ“t exceed the maximum safe operation pressures.
4. To check is pressure regulating devices are well adjusted.

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