- Jerry Schultz, P.E.
Plasticization
For years I have had the pleasure of teaching the three day seminar on automatic sprinklers on behalf of NFPA. For those of you who have attended a class that I taught, thank you. For those of you who haven’t heard me speak, I invite you to register for a program. In the seminars, I get the opportunity to present the standard and illustrate points with anecdotes, stories and real world adventures. Some of these come out in this blog, and one that really hits home with me is the “plasticization” of the world that we live in. In an earlier blog, I wrote about NFPA 25 which requires the inspection, testing, and maintenance of the sprinkler system, but excludes the evaluation of the adequacy of the sprinkler system. The example I used is the modern day garden hose reel. This product has changed from a metal product 35 years ago to a completely plastic product today. My example could just as easily have been an IBM “Selectric” (trade name for an electric typewriter) typewriter verses a notebook computer or the Tonka metal body truck that I grew up with verses the plastic trucks kids play with today. (Not to mention, the electronics stuffed in these newer trucks that have lights and sirens.) These are obvious changes but the issue is so pervasive that we sometimes miss the concept.
If you haven’t seen it, this video shows a side by side fire in a front room where the front room on the left has natural material built furniture, manufactured 40 years ago (couldn’t tell if this was shag carpeting but did notice no disco ball) while the front room on the right has modern day synthetic material built furniture (https://www.youtube.com/watch?v=aDNPhq5ggoE).
One couldn’t ask for a better example of how pervasive and even subtle the plasticization of society is. As evident in the video, the backing on the carpet is synthetic as well as today’s drapes and furniture which are more flammable than cotton, silk or leather and lead to a much more severe, rapidly developing fire.
Keeping in mind that we are talking about the plasticization of society, let’s look at two editions of NFPA 13, Standard for the Installation of Sprinkler Systems, the 2013 and the 2016 editions. Figure 17.1.2.1 of the 2013 edition stated that a Group A plastic that was exposed and expanded and stored on racks was outside of the scope of Chapter 17.
As recently as 2013, we did not know how to address this hazard. In the 2016 edition of the standard, criteria was added for expanded, exposed Group A plastics on racks. The NFPA 13 committee added the criteria based on a series of fire tests conducted by Underwriters Laboratories (UL) under the direction of the Fire Protection Research Foundation. These tests resulted in the current criteria that was added to NFPA 13, (Section 17.2.3.5 up to 25 feet and Section 17.3.3.5 over 25 feet).
This criteria is tough because, not only are vertical barriers required to run the full height of the racks, but a large amount of water is required of the water supply.
For storage over 25 feet, one has to provide a sprinkler with a k factor of 25.2 and assume 12 sprinklers flowing at a minimum pressure of 60 psi. This yields a minimum individual sprinkler discharge of 195.2 gpm. Multiplying by the required 12 sprinklers, means the minimum design flow for the system, (not accounting for inside or outside hose stream allowance) is 2,342 gpm.
Kerry Bell of UL explains the fire test in a video (https://www.youtube.com/watch?v=VzCMxT6qink) that illustrates the severity of the fire.
At first blush it is easy to say, I don’t have polystyrene meat trays stored like this so how does this affect my warehouse? The polystyrene meat tray represents a reproducible Group A, expanded exposed plastic and is meant to represent any expanded, exposed Group A plastic. This classification includes items such as furniture, car bumpers, coolers, certain toys, bedding, and yes, garden hose reels. I would strongly suggest reviewing the Annex in the 2016 NFPA 13 edition where the commodity classifications were completely rewritten to see what products are considered an expanded, exposed Group A plastic. (Note—one of the best changes in the 2016 edition of NFPA 13 is the rewrite of the commodities. The commodity list hadn’t had a major revision since its’ original insertion in NFPA 231 and 231C in the 1970’s.)
I am always asked if NFPA 13 is a retroactive standard and I respond with the classic response—No, per Section 1.4 “The provisions of this standard reflect a consensus of what is necessary to provide an acceptable degree of protection from the hazards addressed in this standard at the time the standard was issued.” I admit, when a new requirement is added for something that has never been addressed before, I believe one has to at least look at the protection scheme that had previously been accepted (probably an engineered approach) and consideration should be given as to whether these new requirements should be retroactive. Keep in mind there are acceptable alternative designs and that you, as a consultant, a designer, an insuring authority or the AHJ (by definition, the term AHJ may cover some or all of these positions and is not intended to apply exclusively to a governmental agency) will be required to assess the previous protection scheme and make a decision if it is still acceptable or should the new requirements be applied. Also keep in mind that in Section 1.4.2 the AHJ has the authority to “apply retroactively any portions of this standard deemed appropriate.”
This is a long way to get to one major issue that I am starting to see in warehousing. Recently I have been involved with several clothing warehouses along with several paper storage facilities. In both cases, there have been discussions on the potential for taking clothes and placing them in plastic totes or storing the paper in plastic totes, in order to reduce the likelihood of the clothing or paper being damaged should a sprinkler activate. Does this change the fire scenario? Of course it does. What is required to be done? One must review the arrangement and make a decision as to whether this becomes a plastic fire. If so, does it become an exposed, expanded Group A plastic on racks and now we have to add barriers, provide a k25 sprinkler, increase our main size, and possibly provide a bigger fire pump? It goes on and on and yet the owner of the warehouse, sees it as protection for the product and not an additional fire hazard.
Next month, I will start discussing solid shelving in racks unless something happens in the industry. Until then, as always, I welcome your comments: j.schultz@the-fpi.com
