Wax coated sprinklers in paint booths 1

[FFP1]

I have been asked to replace 125 painted sprinkler heads in the 9 paint booths at this certain facility. This plant has a long history of painting even when the protective bags are missing......the result is overspray and painted heads.

I cannot find where NFPA code allows or does not allow 165F rated wax coated sprinkler heads in flammable liquid spray paint booths. I will still provide the bags to prevent overspray, but I was thinking a slightly or even heavily painted wax coated head would be more likely to operate than a slightly or heavily painted standard head. Am I correct in thinking the paint on the exterior surface of the wax would fall away when the wax coating on the sprinkler head melts? I would be interested in your thoughts regarding this matter.

It might not be worth the extra expense, because I think NFPA code requires replacement of any and all painted heads (even wax coated heads); however, this facility does not replace the painted heads very often, so I am thinking this might be the best approach to increase the overall reliability of the sprinkler system over the long haul.

Thanks

 

[stookeyfpe]

Wax coated sprinklers are used for corrosive applications. Your problem is overspray during the application of the flammable finish. You do not require wax coated sprinklers or sprinklers protected using a PTFE (Teflon) finish.

I am assuming your facility is located in the US. In the US, the predomoniant fire code is the International Fire Code (IFC). IFC section 1504.5.2 require the sprinklers to be protected by either paper or plastic bags. The thickness of the paper or plastic cannot exceed 0.003 inches. Interestingly this dimension is based on a study done by the Sweden Fire Protection Association and is a valid value. They performed full scale fire tests on sprinklers in this environment and published a paper on their results in the SFPE Journal.

Do not attempt to clean the sprinklers. It won't work and cleaning with a solvent may cause accidental activation of the sprinkler.

NFPA 13 has always required damaged or painted sprinklers to be replaced. See 2002 NFPA 14, section 6.2.6.2.2.

 

[FFP1]

I appreciate your detailed response and I agree with everything you have stated. I am wondering if it would be a code violation assuming my client likes the idea of using wax coated heads in the spray booths.

In a ideal world, the bags would remain on the sprinklers and no paint overspray would occcur.......we have a long history of problems at this location and I am thinking the wax coated heads would provide an extra level of protection in the event some of the heads are exposed to overspray. This client will not replace the painted heads on a regular basis and I am trying to improve the likelihood that the sprinkler system operates when needed.

Thanks

 

[LCREP]

Yes it would be a code violation as Stookey has indicated the code section above. BUT the requirement it to prevent the build up of paint on the deflector and more important on the cap. Even a small amount of paint can hold the cap in place and prevent the head from activating. The question is will the wax prevent the build up of paint on these key areas? My guess is it will not, the residue will remain on the head and result in poor performance or the head not activating. The only way is to do some full scale testing. Install the waxed coated heads, and then after a few months send them to UL for testing. You will need to explain to UL what u are doing since as soon as they see the painted head they will fail. Interesting idea, let us know if you do the UL test and what the results. To be honest I have never heard of using wax coated heads in this application and I have been doing this for 28 years on the insurance side of the business.

I usually tell my customers to change the bags when they change the filters. You would think after the customer has paid to replace 125 heads they would insured this will not happen again.

 

[stookeyfpe]

Every fire in a paint booth I have investigated has been a very rapid flash fire. I think that wax coated sprinklers would make the fire worse because they insulate the sprinkler link or frangible bulb, which slows the response of the sprinkler. In flash fire the wax must be melted and then the sprinkler link or bulb must be heated to a point where the link or bulb fails.

I liked InspLCrep's idea of changing the bags at the same frequency of the filter. I like it because neither the IFC or NFPA 33 has a requirement for when the bag must be changed. The logic is sound and has very good merit. For that, I gave him a star.