Overspray protection

[bobinillinois]

Has any one got a source for true celophane/celophane bags (no thicker than .003") or paper bags for use to protect heads from overspray?

I'm also curious how the heads are supposed to be held on to the heads as NFPA doesn't give any methodology to keep them attatched to the heads they're supposed to protect.

 

[cdafd]

Bags from local grocery store, rubber band or other

If you go cellophane good luck finding something that meets all the specs

 

[PRinspector]

+1 to what cdafd said, I think paper bags hold up better.

 

[Lamuppet]

Check out this:

http://www.cellobags.com/Fold_Over_Flat_Cello_Bags_s/145.htm

PFB355 should do the trick!

Or you could use thin paper bags... As permitted in the NFPA 25 & 13!

NFPA 25 2011
art.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.

NFPA 10 2010
Art. 6.2.6.4  Protective Coverings.

6.2.6.4.1  Sprinklers protecting spray areas and mixing rooms in resin application areas shall be protected against overspray residue so that they will operate in the event of fire.
6.2.6.4.2* Where protected in accordance with 6.2.6.4.1, cellophane bags having a thickness of 0.003 in. (0.076 mm) or less or thin paper bags shall be used.

 

[Lamuppet]

Cdafd,

There's a problem with normal sandwich bag, as explained in the annexes of the NFPA. Paper bag is expensive... The link that I gave in the last post, is much cheaper and meet the specifications asked in the codes... 1.2 mils, equal 0,0012 in, so the thickness is less then the 0,003 required.

NFPA 25 2010
A.5.4.1.7.1 
Typical sandwich bags purchased in a grocery store are generally plastic, not cellophane. Plastic bags have a tendency to shrink and adhere to the sprinkler prior to sprinkler activation, creating the potential for disruption of sprinkler spray patterns. Bags placed over sprinklers need to be true cellophane or paper.

 

[Sdpaddler50]

When i worked for FM, we would accept a sandwich bag, paper bag, whatever. So long as it was thin, it will burn off very rapidly and not present any adhesion/obstruction issues. I have seen 50K sq ft, high value paint booths used to spray parts in the aerospace industy worth big money, and the heads were covered with the same grocery story little baggies my kids used to bring their sandwich to school.

 

[stookeyfpe]

In 1993 the Swedish National Testing and Research Institute published a report titled Response Characteristics of Glass Bulb Sprinklers in Mounted in a Paint Spray Booth. The experiments involved 27 different tests of various plastic films and papers that were coated with one or more layers of paint to determine which materials had the quickest response time. The report also revealed the paper outperformed plastic, but the difference was statistically not significant. The bigger problem is not the bag material - it is the number of layers of paint on the bag. They concluded that a rigorous replacement schedule when overspray is witnessed offered the most efficient and cost-effective means of protecting automatic sprinklers in spray booths.

 

[cdafd]

Lam,

Aren't these to thick

http://www.cellobags.com/3_x_5_5_Cello_Bags_Fold_1_2_mil_p/pfb355.htm

Still not into that metric stuff

 

[cdafd]

Sorry meant to say "paper bags" from local grocery store

 

[Lamuppet]

The codes don't statuate about any minimum thickness...

"thickness of 0.003 in. (0.076 mm) or less", so as long as I understand well the codes, 0.0012 in is less then 0.003 in...

(A "mil" is a thousandth of an inch, so it's not really metric stuff... Ok half half! )

http://en.wikipedia.org/wiki/Thousandth_of_an_inch

 

[cdafd]

lam
thanks, don't understand measurement sometimes.

 

[LCREP]

"The bigger problem is not the bag material - it is the number of layers of paint on the bag. They concluded that a rigorous replacement schedule when overspray is witnessed offered the most efficient and cost-effective means of protecting automatic sprinklers in spray booths."



I always tell my clients to change the paper bag when you change the filters, this ensures a minimal amount of build up of overspray on the bag. Do not forget to cover the heads behind the filters and at the top of the ventilation shaft.

 

[PRinspector]

I always tell my clients to change the paper bag when you change the filters, this ensures a minimal amount of build up of overspray on the bag. Do not forget to cover the heads behind the filters and at the top of the ventilation shaft.

GOOD POINT... This is always overlooked........ I got the deer in the headlight look when I ask if these sprinkler heads have the bags.

Lou