Avoid Header in Weekly Test of Diesel Fire Pump?

10/26/2020

Are there any drawbacks of testing a diesel-engine fire pump on a main header where other diesel pumps are connected to, instead of a test header?

This is happening in my plant because the test header is is large enough that it would require frequent throttling of test header discharge gate valves for each pump, which has started to wear out and not hold pressure.

Also, what is the minimum flow requirement for weekly diesel pump testing considering the test header doesn't hold? Do we need to run 0%, 100%, and 150% flow test each week?

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4 Comments

Dan Wilder

10/26/2020 09:09:25 am

To answer your question, typically the length of the test header is limited to 15 feet or the supply piping to the test header must be increased by one pipe size (unless hydraulic calculations area provided). In addition, the actual pipe supply to the test header must meet sizing requirements per NFPA 20-Table 4.27 (I'm referencing the 16' edition but that sizing would apply to whenever your pump was installed).

If you can comply with those requirements, there is no issue testing from a different location (personally, I would recommend testing from both locations for a time to establish the new test norms while making sure the older tests still fall within the established test result criteria).

I also think you need to purchase a NFPA 25 to keep for future onsite inspections.

As an owner, you are responsible for the ITM of your pump (or designate someone to perform these actions) so thank you for taking that on but weekly "flowing" of your pump is not required.

Within NFPA 25-2020 Edition, Chapter 8 is Fire Pumps. The summary Section 8.1.1.2 indicates the frequency of testing.

Running the pump is a Weekly activity per 8.3.1.1 but no flow is required for this test. Section 8.3.2.4 indicates that the test shall be a minimum of 30 minutes. This accomplishes a couple items:
-Verifies running speed
-Identifies any air intake, overheating, or excessive/limited water leakage from either the packing or relief valves
-Uses fuel (this means fresh fuel is added at intervals less than it takes for the diesel fuel to go bad-typically 6-12 months)

With flow conditions, your three points are minimums as defined within 8.3.3.1. You may even take advantage of a flow meter on your pump (which then only requires actually flowing water every 3 years, the other two flows are accomplished within the closed system and measurement by the meter).

See below link to purchase of NFPA 25 if you wish.
https://www.nfpa.org/codes-and-standards/all-codes-and-standards/list-of-codes-and-standards/detail?code=25

FRANK J. HERRICK

10/26/2020 10:22:29 am

I've found that the commonly used valves on a fire pump test header don't provide a positive lock.

Try using the Akron Brass 1828

Hydrant Valve 1828
2 1/2'' Hydrant Valve
2-1/2" Hydrant Valve. These full flow hydrant valves come with a Tork-Lok handle for more positive handle positioning.

Adapter easily removed for seat adjustment. Pyrolite construction.

Franck

10/26/2020 11:55:54 am

As indicated by Dan, no need to test weekly at 0% and 100% and 150%.
You can test it at 0%.
The purpose is to check the following:
The following items should be checked during the test:
• Record the system suction and discharge pressure gauges readings
• Record the pump starting pressure
• Check the pump packing glands for slight discharge
• Check for unusual noise and/or vibration

In addition, the weekly 20-30-minute test accomplishes the following on diesel fire pumps:
1. Proves the engine can start and produce power.
2. Renews the oil film on internal parts to prevent wear and corrosion.
3. Drives off condensation in the lubrication and exhaust systems.
4. Loads the engine cooling system for sufficient duration to detect if there is a problem

Some companies test it at the nominal flow (100%) so that they can check weekly the actual performance of their pumps, but the ones I know are located in Europe when we have a test line and a flowmeter and the test water is going back to the water tank (no waste of water for 30 minutes, except the one used for cooling the diesel engine, and much easier to perform than using a test header and pitot tubes :)).

Jonathan Sullivan

10/26/2020 02:16:18 pm

This seems like a smart practice. What drives the requirement for the tank in EU?

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