Sprinklers in Paint Booths

[mannyman]

What type of sprinkler (preferably concealed SR 11.2k) is usually used in a paint booth. Client wants pipe to be concealed, uprights are out of the question. So my dilemma is EH GR2 for paint booth requires 11.2k minimum orifice and I cannot have QR spkrs. Any suggestions?

 

[cdafd]

Normally see pendant with approved protection, all piping outside the booth.

Pre fab booth I take ???

 

[chicopee]

...and cover your sprinkler heads with plastic sandwich bags so that paint residue does not coat the fusible links

 

[Sdpaddler50]

I dont believe concealed heads are allowed for a paint booth.

Also, you may need heads in the exhuast duct if the paint loading is such that it will accumulate on the interior of the ducts.

Provide an isolation valve for the head(s).

 

[LCREP]

Sandwich bags not a good idea, see below is from Nfpa25 handbook:

5.4.1.7.1* Sprinklers subject to overspray accumulations shall be protected using cellophane bags having a thickness of 0.003 in. (0.076 mm) or less or thin paper bags.
Testing has shown that lightweight cellophane or paper bags will not adversely affect the operation of the sprinkler. Sprinklers protected by lightweight cellophane or paper bags may require more frequent inspection than the annual inspection outlined in 5.2.1.1.2 to prevent excessive buildup on the bags. Depending on the use of the spray coating area, the inspection and subsequent replacement of the bags may need to be done daily. In prior editions, NFPA 25 allowed the use of a plastic bag, but this was changed due to concerns about the potential for a plastic bag to shrink prior to sprinkler activation and disrupt the discharge pat- tern. Exhibit 5.28 illustrates a sprinkler protected from overspray by a cellophane bag.

 

[mannyman]

Thanks to all who replied. Yes its a prefab booth and I did install heads in exhaust manifolds and stacks. Yes the paper bag is my last resort because the client is very picky. He wants the cleanroom look finishing plates. But as I feared the traditional pendant will have to suffice.

 

[Sdpaddler50]

It appears nfpa 25 is dissecting a flys wing. I can't see how a plastic sandwich bag is going to retard the heat significantly but a plastic cell phone Baggie is ok.

Plastic baggies similar to the one in little joeys lunch box have been going on these for decades. No problems I have heard of because of this.

 

[cdafd]

If not specified as to thickness and material

You will find a heavty heavy duty trash bag cut up and used

 

[Sdpaddler50]

Heavy duty trash bag? No, the reference was to the often used sandwich Baggie which is what I have seen used for 26 years, and will continue to recommend to my clients. let's not miss the forest through the tress and complicate things that should be simple.

 

[LCREP]

Sp50

Make sure the bag meets the thickness requirement if not you could run into a problem with the AHJ. I ALWAYS tell my clients the same thing, remove the plastic and use a paper bag. I have a hard time looking at a bag and measuring the bag thickness to see if it is .0003 in, I can figure out what a paper bag looks like...lol.

I spend a lot of time looking at the booth as it is most common cause of loss for us. I can not tell you how many problems we find with booths, no sprinklers in the stack or behind the filters, no shut off valve, nonrated electric in the booth, spraying outside of the booth, mixing of flammables outside designed areas, etc etc. Yea covering the sprinkler is just one of the things we look at.

 

[skdesigner]

Sdpaddler50, I read somewhere that the reason for cellophane and not sandwich bags is what happens when they are exposed to heat. The cellophane essentially disintegrates and disappears, while the heavier plastic bags simply melt onto the sprinkler and coat everything. Presumably the allowance for paper bags is for the same reason.

R M Arsenault Engineering Inc.

http://www.rmae.ca

 

[chicopee]

Remember it is either paint residue on the fusible links or on these thin PVC sandwich bags for the heads within the booth. I would not expect paint residue to get into the exhaust ducts as there will be paint filters , therefore, those heads can be left the way they are.

 

[stookeyfpe]

Before speculating like my girlfriend at the grocery store (Honey, do we want paper or plastic?) please read the attached research paper that evaluated both paper and plastic bags over sprinklers in spray booths. I think LCREP made the suggestion that is consistent with the researcher's findings: change the bag (paper or plastic) everytime the filters are replaced.

 

[Sdpaddler50]

It's still a non issue to me. I have spent a lot of time around heavy manufucturing plants. The ones that have paint spraying often have much bigger fish to fry in regards to fire code compliance/loss control issues rather than whether they are using a little sandwich bag or a slightly thinner cell phone Baggie. If the fire load is sufficient it will burn that little bag off, the head will pop and all will be well. Not speculation, just common sense.