Use Quick Response Sprinklers in Dry System?

1/8/2020

I would appreciate some feedback on using quick response sprinklers in a dry system. I have found no reference in NFPA 13 indicating specifically if QR Uprights can or can not be used. Therefore, I assume that they are acceptable providing it is a light or ordinary hazard classification.

I have researched and found varying opinions. I believe fire testing shows that the use of QR sprinklers in dry systems can help decrease fluid delivery time. However, with more sprinklers operating before the water arrives to control the fire, some argue that there is increased system demand. I agree with both scenarios, however, I don't believe the amount of sprinklers operating would exceed the design area of a properly calculated system.

I would love to hear some different opinions on the subject.

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4 Comments

Thomas Jones III

1/8/2020 10:08:52 am

QR are allowed for dry systems and actually are required per NPFA 13 (2010) 8.3.3.1, if you dry system protects a light hazard area.

Mike L

1/8/2020 01:44:58 pm

Sprinkler RTI (fast response vs standard response) and water delivery time are two totally separate items.

Quick response, which is a type of fast response category of heads, refers to how quickly the sprinkler head will fuse given the rise in ambient air temp caused by the hot gases of the fire.

Water delivery time for dry systems is dependent on two factors, valve trip time and water transport time. Valve trip time is dependent on valve design, system pressure and the use of quick opening devices. Water transport time is dependent on the piping arrangement.

Because of the delay in water availability in dry systems, the hydraulic area being calculated is increased by 30% to account for the fact that more sprinklers will operate.

B.P.

1/8/2020 05:01:28 pm

Excellent answer! I believe NFSA did conduct full scale fire tests which suggested that quick response sprinklers, by nature, did activate quicker decreasing the delay in water delivery to the fire and consequently reducing overall ceiling temperature.

As far as actual fluid delivery time, if a greater number of QR sprinklers activated than SR, it could impact trip time and water delivery time by expelling a larger volume of air faster? Correct?

B.P.

B.P.

1/8/2020 06:49:11 pm

Does anyone know definitively what FM recommends? I have heard discussion that they don’t recommend QR sprinklers in dry system installations but, have been unable to find anything in the data sheets.

B.P.

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