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AHJ Challenge

Calling all AHJs!

Each issue, AFSA’s Engineering & Technical Services Department presents one or multiple challenges for AHJs. Besides challenging yourself and your co-workers, working these problems is excellent preparation for professional certification tests and also may count as continuing education hours. Check with your certification organization to see if this exercise meets its criteria. To participate in this challenge, carefully read and work the problems, and submit your answers online at firesprinkler.org/ahjchallenge by April 15, 2021. One winner will be pulled at random from those who answer correctly to receive some AFSA swag! Answers will be published in the next issue when new challenges are presented. 

March/April Challenge

The following questions are based on NFPA 13, Standard for the Installation of Sprinkler Systems, 2019 edition.

1) Baffles are used to prevent cold soldering of sprinklers when minimum distances between sprinklers cannot be maintained but are not prescribed for all sprinkler types. Which two of the following sprinkler types have prescriptive requirements to use baffles?  

A. ESFR sprinklers

B. Extended coverage pendents 

C. CMSA sprinklers

D. Residential sprinklers

2) A 725-gallon capacity dry pipe piping system has been installed with a quick-opening device. What is the maximum water delivery time from the time the inspector’s test valve is fully open to the time of initial water discharge?

  A. 50 seconds 

  B. 60 seconds 

  C. 15 seconds 

  D. No delivery time requirement 

3) When witnessing a hydrostatic test on a new system install, you observe that the system water supply pressure is 168 psi. What is the minimum required system pressure per NFPA 13 to perform the test successfully?

       A. 200 psi 

       B. 218 psi

       C. 175 psi 

       D. 150 psi  

4) In a long corridor, architectural features are creating four different shadow areas for a residential sprinkler. What is the maximum
shadow area permitted per NFPA 13? 

       A. 15 ft2 per shadow area 

       B. 15 ft2 per sprinkler protection area

       C. 10 ft2 per sprinkler protection area 

       D. Unlimited as long as all of the obstruction rules are met 

January/February Answers 

All answers are based on the 2019 edition of NFPA 13. Questions may have more than one correct answer.

1) B, C & D. NFPA 13 section 6.10.2.2.2 permits a hydrostatic test of underground piping to be accepted when there is a pressure loss less than 5 psi or no visual leakage as opposed to aboveground piping which requires no drop in pressure and no visual leakage. As long as the gauge pressure increases or decreases less than 5 psi after the testing allowance or there are no visual leaks, the test is acceptable.

2) C & D. NFPA 13 section 8.2.3.3 permits systems not more than 500 gal to be installed without a quick opening device and not be required to meet water delivery time requirements. 

3) D. NFPA 13 Table 10.2.4.2.1(a) defines the maximum area of coverage for sprinklers in a Light Hazard Occupancy with both combustible obstructed and unobstructed construction spaced less than 3 ft on center shall be 130 square feet.

4) A. False. NFPA 13 section 27.2.4.2.1 requires the user to make the design area rectangular in shape by having a dimension parallel to the branch lines at least 1.2 times the square root of the design area used.


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