Fire Pump On or Off During Main Drain Test?

5/24/2024

When conducting main drain test on a sprinkler system with a fire pump, should the pump be on or off?

AHJ generally wants the pump to be on in this area. Thanks.

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10 Comments

Dan Wilder

5/24/2024 07:51:27 am

The test should be done at the main drain closest to the supply/source with the pump off. NFPA 25 says "for each water supply lead-in". It would be near impossible to decern a water supply degradation instead of a pump degradation, or a combination of both, with the pump running based only on a main drain test.

13.2.2* Main Drain Test.
A main drain test shall be conducted annually for each water supply lead-in to a building water-based fire protection system to determine whether there has been a change in the condition of the water supply.

13.2.2.1 also allows a single main drain test for buildings with multiple systems per water supply lead-in.

This is also reinforced by looking at Table 5.1.1.2 for the summary of sprinkler systems with no frequency provided and referencing Chapter 13.

Glenn Berger

5/24/2024 08:15:32 am

Depends -

Is the water supply to the sprinkler system solely dependent on the fire pump? Or can the municipal's water supply the sprinkler system without the fire pump operating?

Derek G.

5/24/2024 08:34:52 am

Agree with Dan here. It should be off, but as an AHJ and former fitter, I would also capture the numbers with it on.....it doesn't hurt to have both sets of values.

Jack G

5/24/2024 09:16:28 am

The fire pump should be off.
The main drain test is used to determine degradation in the incoming water supply.
A separate test —— fire pump test — is used to determine changes or degradation of the fire pump.

Franck

5/24/2024 09:18:28 am

If you are talking about the 2 in. drain test, it should be done with the pump on.
I always did it that way (and was trained to do it that way) for more than 30 years as an insurance loss prevention engineer (for every survey).

The purpose of this test is to drop the pressure at the ACV very quickly and check if the fire pump starts and if the pressure is coming back to the required value (as per previous tests).
If not, this means that you have partial obstruction between the fire pump and the ACV.
If you do this test with the pump off, the the pressure will drop, but will not come back up (you just drop the pressure in the system with no way to compensate). This means that you will have no idea on possible obstruction on the line.

To check possible pump degradation, you will check it anyway with the annual flow test of the pump.

Franck

5/24/2024 09:21:38 am

By "on", I mean "pump in automatic mode". But the pump is not running when you start the 2" drain test. You start the pump by pulling down the pressure in the system.

I understand "off" in your question by "pump in non-automatic mode".

Steve Cooper

5/24/2024 09:41:00 am

With the fire pump off, would make sense per code, but your AHJ could just want extra values and tests. Many AHJs we work with like to ask for much more than NFPA requires.

Matthew Mueller

5/28/2024 07:45:41 am

This was something that was taught to me early on and was a significant change to how my company, and most companies in our area had been doing this test. The fire pump is an integral part of the designed water supply. In addition, all tests required by NFPA 25 are required to be performed with the fire pump in "on" (automatic) unless impairment procedures are followed.

NFPA 25, 2023 Ed.:
4.4 Water Supply Status.
During inspection, testing, and maintenance, water supplies, including fire pumps, shall remain in service unless under constant attendance by qualified personnel or unless impairment procedures in Chapter 15 are followed.

Excerpt from NFPA 25 Handbook, 2023 Ed.

Testing Procedure for 13.2.2
Main Drain Test

Purpose

The purpose of conducting a main drain test is to determine the adequacy of the connected water supply and to detect significant reductions that might adversely impact the system operation by comparing the results of the current test to a previous baseline test pressure. The test does not provide absolute assurance of an unobstructed waterflow or fully opened valves, but it provides a reasonable check against gross changes in the water supply conditions. This testing is required for each water supply lead-in to the building. Where a single lead-in supplies multiple risers, a single main drain test is acceptable, except that additional main drain tests must be conducted so that every system backflow preventer and/or pressure-reducing valve is exercised. These additional tests would be necessary for situations such as those that include individual floor control valves equipped with pressure-reducing valves.

Tools/Equipment

No special tools are required.

Procedure Steps

Systems Supplied by a Fire Pump

1.
Prior to any testing, notify the fire department and/or the alarm monitoring company, as well as the facility representatives, that testing is going to be conducted.

2.
The pressure gauge readings collected on the suction side of the fire pump during the annual fire pump test can be used for comparison purposes at a common flow rate in lieu of conducting a separate annual main drain test.

a.
During the annual fire pump test, record the static pressure (no flow) reading on the pressure gauge on the suction side of the fire pump.

b.
During the rated flow (or other common flow rate) of the annual fire pump test, allow the pressure to stabilize and then record the residual pressure reading on the pressure gauge on the suction side of the fire pump.

3.
Where the sole supply of water to the fire pump is through a backflow preventer and/or pressure-reducing valve requiring a quarterly main drain test, the test should be conducted in accordance with the following procedure with the fire pump in the operating position.

a.
Check the area surrounding the main drain outlet to ensure that there are no obvious conditions that would prevent water from being discharged safely or cause direct damage in the immediate vicinity. Where the discharge of water is to an area subject to potential freezing conditions, the facility representative should be advised of the potential for icing conditions.

b.
On systems where the main drain is connected to an alarm valve or other arrangement where the flow of water from the main drain will result in the activation of an alarm device or water motor gong, the shutoff valve (where equipped) in the connection to the alarm sensing line should be closed to avoid unnecessary sounding of the alarm.

c.
Record the static pressure (no flow) reading on the pressure gauge on the suction side of the fire pump.

d.
Open the main drain valve slowly until it has reached the fully open position, initiating the fire pump operation. Allow the pressure to stabilize, then record the residual pressure reading on the pressure gauge on the suction side of the fire pump.

e.
Slowly close the main drain valve to avoid water hammer, record the time for the pressure to stabilize, and record the return static pressure reading on the pressure gauge on the suction side of the fire pump.

f.
Allow the fire pump to operate for 10 minutes for an electric fire pump or 30 minutes for a diesel fire pump, followed by a shutdown of the fire pump and restoration of automatic operating condition.

g.
Return any shutoff valves in alarm sensing lines that were closed during Step 3b to the normal operating position.

4.
Upon completion of all testing, notify the fire department and/or the alarm monitoring company, as well as the facility representatives, that testing is complete. Reset the fire alarm system as necessary.

Jay

5/29/2024 03:45:40 pm

I agree with #2.....there is no need to do a main drain test on a system with a fire pump because the suction pressures from the annual pump tests can be compared to identify a reduced water supply

Matt G

8/15/2024 04:35:28 pm

That is not entirely correct Jay. Facilities that have fire pumps in stand alone pump houses that feed underground piping that supply the sprinkler risers in the main building(s) certainly need main drain tests completed. This is to ensure no isolation valves are shut / partially shut or major deterioration / blockage of the underground supply piping.

As to pump running versus not running for main drain tests, I have heard it argued both ways. My company performs them with the fire pump off, unless fed by a storage tank. We drop the system pressures to the city pressure to do so properly.

Fire Pump On or Off During Main Drain Test?

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