Forward Flow Testing of Backflow Devices ??

[LCREP]

Do you enforce and or provide this service to your customers? See code sections below?

I was teaching a class the other day and was covering this section in the code and I asked the class of 30 ( a mix of fire inspectors and sprinkler contractors) if they did the testing or required the testing. Only 2 in the class indicated they either enforced it or did it. Most did the backflow test as required by many health departments, in NJ it is required quarterly, but few did the forward flow test.

Many had no idea it is required by NFPA 25. What I find interesting is NFPA 13, see below, requires a test header or some way of testing the device. How many plan reviewers or inspectors are enforcing this section of NFPA 13?

The forward flow test is required to make sure the springs are opening at the required flow rate (sprinkler or standpipe system gpm demand) and do not present an obstruction to the flow. The following is what I have witnessed when contractors do this test. A calibrated gauge is installed on the inspection ports on each check assembly. Water is flowed at the system demand and the psi pressure loss is measured between the 2 gauges. The psi pressure loss is compared to the manufactures cut sheet for the backflow device. The psi pressure loss should match the loss at the demand gpm, if it does the device is OK, if not, further investigation is required. The other option is to take the device apart and conduct an internal inspection.

So what do you do?

As per NFPA 25, 02 12.6.2.1* All backflow preventers installed in fire protection system piping shall be tested annually in accordance with the following:
(1) A forward flow test shall be conducted at the system demand, including hose stream demand, where hydrants or inside hose stations are located downstream of the backflow preventer.
(2) A backflow performance test, as required by the authority having jurisdiction, shall be conducted at the completion of the forward flow test.

NFPA 13, 02 Section 8.16.4.6.1 Backflow Prevention Valves. Means shall be provided downstream of all backflow prevention valves for flow tests at system demand.

8.16.4.6.1A: The full flow test of the backflow prevention valve can be performed with a test header or other connection downstream of the valve. A bypass around the check valve in the fire department connector line with a control valve in the normally closed position can be an acceptable arrangement. When flow to a visible drain cannot be accomplished, closed loop flow can be acceptable if a flowmeter or site glass is incorporated into the system to ensure flow. When a backflow prevention device is retroactively installed on a pipe schedule system, the revised hydraulic calculation still follows the pipe schedule method of 11.2.2 with the inclusion of friction loss for the device.


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Fire Sprinklers Save Firefighters’ Lives Too

Not ALL Sprinkler Systems Are Created Equal! An Inadequate Sprinkler Design Is JUST As Bad As A Nonsprinklered Building!! When Occupancies Change So Should The Sprinkler System. See NFPA 25, 2002, Edition, Section 4.1.5, 4.1.6 & 4.1.6.1.

 

[SprinklerDesigner2]

I am well aware of the requirements but in Georgia the testing is ignored for the most part.

Everyone seems to hold to the idea by reversing the check valve on the FDC you can meet the requirements, which I suppose is correct on many light hazard systems, but but won't work on larger 6" and 8" systems.

Testing on systems having standpipes would not be a problem nor would large yard systems with hydrants downstream a pit. Systems with fire pumps would be easy as long as the backflow preventor was installed upstream the fire pump which it shouldn't be.

The system that will present a problem is the one with the .60/2000 using a city supply of 65 static, 45 residual at 1,100 gpm which would probably require an 8" riser, 6" mains and 2 1/2" or larger branch lines on a grid. With this you'll never get 1400-1500 gpm through the 4" FDC.

But to answer your question I've never specifically forward tested one yet. Fact is I've never heard of a local authority requiring it to be done.

 

[LCREP]

Has Ga adopted NFPA 25? If so, does your inspection contract indicate it will meet NFPA 25? What liability do you think your company assumes by not testing should a loss occur and the cause was a malfunctioning backflow device? I assume (I know what happens when u assume) since NFPA 25 requires the test, it must have loss data to support the requirement? Anyone have any background on the requirement, or has witnessed this problem?

I am on the insurance side of the house and makes we wonder why contractors would miss an opportunity to make a profit on a required test?

****************************************
Fire Sprinklers Save Firefighters’ Lives Too

Not ALL Sprinkler Systems Are Created Equal! An Inadequate Sprinkler Design Is JUST As Bad As A Nonsprinklered Building!! When Occupancies Change So Should The Sprinkler System. See NFPA 25, 2002, Edition, Section 4.1.5, 4.1.6 & 4.1.6.1.

 

[SprinklerDesigner2]

Has Ga adopted NFPA 25?

Yes.

Georgia also requires inspectors to have NICET III certification in inspecting but that is a process where some grandfathers are still working on getting their certificates.

To answer your question on liability, forward testing of backflow devices notwithstanding we already assume far to much liability inspecting then it's worth.

 

[cdafd]

NFPA 13, 02 Section 8.16.4.6.1 Backflow Prevention Valves. Means shall be provided downstream of all backflow prevention valves for flow tests at system demand.

Have seen them pipe above the backflow and either pipe through the fdc or just run a pipe to outside with butterfly and tamper monitored normally closed.

started requireing it about six months ago, and have been requireing the backflow test for about nine years

 

[DonPhillips]

"NFPA 13, 02 Section 8.16.4.6.1 Backflow Prevention Valves. Means shall be provided downstream of all backflow prevention valves for flow tests at system demand."

I enforce this during plan review.



Don Phillips

http://worthingtonengineering.com

 

[ContractorDave]

I see my on-line codes have updated 25 to 2008 so chapter 12 is now water mist. At any rate what LCREP points out about 12.6.2.1 (now 13.6.2.1) is fine, but then the following 13.6.2.1.3 (repeated verbatim in 13.6.2.2): " Where connections do not permit a full flow test, tests shall be conducted at the maximum flow rate possible."... seems to be what one would call a weasel clause.

Also ""13.6.2.1.1 For backflow preventers sized 2 in. (50 mm) and under, the forward flow test shall be acceptable to conduct without measuring flow, where the test outlet is of a size to flow the system demand.""... this "without measuring flow" seems to permit an amount of vagueness.

Thoughts?