Covering paint spray booth sprinkler heads, tested? 1

[tom krupica]

Does anyone know of a test that measured the response time of a covered or 'bagged' sprinklerhead in paint booths? I found a 1993 test done in sweden and it was a very comprehensive test that showed the response time to be 2 to 5 times longer than without covering. Even painted heads had a close to normal response time. The paper bags were the worst with up to 5 minutes response time, and the cellophane was still bad with 2 minutes. The uncovered heads went off in 42 seconds.
This next link demonstrates that a sprinkler head will respond in under a minute if uncovered, then they demonstrate what a fire will look like at 2 minutes.

https://m.youtube.com/watch?v=VEXav_iBEZ8

If a covered sprinkler head takes longer than the designed 1 minute or less, then covering them is not a good solution and is very dangerous.



file:///C:/Users/Tom/Downloads/Response_Characteristics_of_Glass_Bulb_Mounted_Sprinkler_Heads_Mounted_In_A_Paint_Spray_Booth.pdf

 

[tom krupica]

The nfpa33 2016 also calls training 'required' and to be documented. So bodyshops are to train their people about static electricity, how the sprinkler works, cleaning the booth, removing the dry overspray, etc. So if 1000's of shops are letting paint get on their heads, then they also arent training. So more violations to be fined. They should just fine the issue. There isnt another profession thats allowed to spray flammables like this, and for the code to interject with an untested device it doesnt seem possible. Why say cellophane? or thin paper? Why measure the cellophane but not the paper. Everything else about the booth and sprinkler system is very technical and has been engineered and tested. Just this rube goldberg device is like that.

 

[tom krupica]

The inspections that are done yearly are to note if a head has paint on it. So someone knows its there. The fire dept then demands they be replaced. And should now just fine them so they can pay for the follow up inspections.

 

[tom krupica]

My fire inspector said he has not seen paint on the bags of other shops. So they dont need the bags either.

I think it needs to be addressed because an uncovered head will save someone's life, and the covered/bagged head will delay it long enough to kill someone.

 

[tom krupica]

The wording of 'location or covering' was added in the 2007 edition. Prior to that they just said 'protect'. My argument back then was that we are the protectors, we as the workers do the protecting. We dont need no stinking baggies.

 

[tom krupica]

I did a test this morning, the uncovered head popped at 155 before the tightly covered cellophane head hit 83 degrees f. The cellophane did not distort or shrink or melt at all at 155. the uncovered head was not loaded with water either, which would keep it even cooler.

 

[MGXFP]

You seem very passionate about this topic.

Have you considered using this abundance of energy to have the adopted codes and standards changed based on what you do in your paint booth? None of us here can really help you change the building code.

I can visualize you taking this crusade on the road and educating people from coast to coast with what most of us spend minutes deciding.

 

[tom krupica]

I was in a fire once. Burnt my right side and all my skin fell off my arm and hand. Laquer thinnner fume caught by static. I stumbled outside and it was raining. I remember thinking how nice it was that is was raining right then. It cooled the skin and while the adrenaline was pumping it was enough to soothe it. I've had nightmares about burning and not getting any water.
Now we keep our humidity at 35 percent so we don't get static.
It's all healed and you can only tell in bright light. We won't be bagging our heads.
Like Ive said Ive know about the bags since 1993. I cant believe they are still even considered. A thin wrap of toilet paper might be a good covering.

 

[tom krupica]

I think when im done the code will only allow some other type of cover, probably a pop up mechanical device triggered by smoke or heat.

 

[UFT12]

Tom, what you write here is well respected but it seems to me that you are too focused on your specific booths. Working daily for years on spray booths and turn key installations of large automotive paint shops for practically any automotive manufacturer, I have never experienced sprinkler heads inside booths not getting loaded with paint. Of course it would be great to be able to install the heads in such way that remain clean but to me it is simply impossible. We have run numerous simulations of air dynamics simulating air patterns in production conditions in our booths and scrubber sections and, depending of course of type of system, we always try to install the heads in places where the air flow is not fully developed or running slower. Nevertheless, our experience shows that the heads are getting paint regardless. In the booth and blowing air from above, you might have pendent sprinklers fairly clean but what about the scrubber? What about the exhaust ducts where space is tight and velocities are higher? The heads are always getting loaded.

Moreover, it looks to me in these tests they didn|t use the right type of bags. In the conclusions I read that "...the covers did not burn off during the test, despite the fact that they were located relatively close to the flames". It looks to me like the bags selected were not the appropriate type or they didn't considered other types of bags although NFPA 33 & the NFPA handbook are cited in the report. In addition, the plastic bags used in the test which resulted in 2 to 5 times increase of activation time, were plastic bags made of polyethylene and not cellophane as NFPA 13 & 33 state. Cellophane is not polyethylene and it does not shrinkwrap on the head which can potentially affect response time. Cellophane tends to burn at lower temperatures than the activation of head and therefore does not affect response time, at least to a negligent level.

 

[LCREP]

UFT

You bring up a good point regarding the air plenum and heads being painted. It does not take much for a filter not fitting properly or not installed in a small area for the paint to be on the sprinkler behind the filter and at the top of the duct. Dry filters were the worst for painted sprinklers. I would always ask, what do the sprinklers look like you can not see, after a blank stare they would say what sprinkler? After explaining the requirements for sprinklers behind the filter and at the top of the ductwork they would have that no one ever asked me that question moment.

 

[tom krupica]

I agree to bag the plenum and duct heads because they are in the line of spray. Its the main heads over the cars that the human would be near that I think should be kept clear of any cover. I bag the duct heads and change those bags, but they never get wet spray on them. Its just fine duct particulate. The code calls for trying to place the heads out of the path of spray, If the heads near the car that are overhead are getting paint on them then someone is not 'protecting them' then they should be bagged. Ny point is 'all heads' do not require to be bagged. I tested the correct thickness of cellophane and it shrinkwraps. It starts to shrink at 155, when the head is supposed to blow. So the cellophane blocks the water. A shroud would work better, like strands of cellophane hanging down. It would allow the heat to blow the head and the strands would blow right out of the way and not restrict the water. I attached a picture of what cellophane looks like at 155f.

 

[tom krupica]

If the fire is in the plenum then its out of control already.

 

[tom krupica]

I still have not seen any proof of any real tests on the cellophane or thin bags. Wax is the answer, it melts at 140 and would fall out of the way taking any paint with it, then the heads would not get restricted by paint or bag. A good smear of a wax from a toilet bowl ring on each side of the head and paint wouldnt stick to it. It would wash off.

 

[tom krupica]

cellophane of the described thickness in the code melts at 350 degrees. Well before that it shrinks and wraps the head. Its a bad idea, no one tested that.

 

[tom krupica]

And a paper bag that someone would use is like a lunch bag. It keeps the head cool for 5 minutes. The paper just cooks and the air inside doesn't change much. Very good insulator. In 5 minutes the entire booth is consumed with fire. I'll bet booth fires are always devastating because of the bagging.

 

[tom krupica]

This is cellophane bag allowed to get to 425 and the head is blown. The water cools off the plastic and it stays behind restricting the flow, just like the feared paint was supposed to do. I attached a picture.

 

[tom krupica]

Of the tests I did with bags being placed looser than the picture shows, there was a longer delay, the inside cellophane bag temp was at 86 f when the outside was at 160.

 

[LCREP]

Tom,

All sprinklers have a thermal lag, so we do not expect the head to go off exactly at the temp noted on the sprinkler. In fact unless the sprinkler is rated as a quick response the lag can be a few seconds to over a minute depending on how hot the fire is and the proximity of the sprinkler to the fire. The sprinklers installed in a paint booth are not by code required to be quick response. The sprinklers in the both are met as property protection not life safety.

I was an instructor at a fire training center and set off 1000's of fires to demonstrate how sprinklers operated. We used a 3 sq. Ft pan filled with 1 gallon of alcohol about 2-3' below the sprinkler. Sometimes the sprinkler would go off in 30 seconds sometimes 1 minute, we actually had fires where the alcohol burned and never set off the sprinkler. We had temperature probes at the ceiling and typically had ceiling temperatures over 200f for a head rated at 155-165f, all heads were standard response. The only time the sprinkler would activate within a few seconds were when we used ESFR heads or residential sprinklers.

My point being a lot of variables in testing with many different outcomes so what you experienced may be different just by changing a few variables.

 

[UFT12]

Tom, I am reading your findingsw ith great interest. One thing I would like to comment though is whether the tests are conducted similar to a real case fire scenario meaning letting the bag and head heating up from some distance below, let's say 4 to 5 m, gradually instead of bringing a heat source some few cm away from the head. It would be nice, anyway, to document your results in a document, in a similar way just like the Swedish report.

 

[tom krupica]

Im building a container to hold the heads and actually have them loaded with water. Then I plan on having 2 thermometers inside the bags and two outside and filming the entire tests. We plan on burning paper and automotive paint with cardboard and place the fire at car height and have the heads at 8 feet or so, whatever the standard automotive booth is. Ill probably do ten tests of each variation. Ten with no bags, ten with paper bags, and ten with cellophane bags. They will be slow start and gradual building fires, and no flash explosions. If a car was masked off and had paint sprayed on it and then ignited it would be a very hot fire quickly. So we may try a small building fire and then hit it with 500 degree hot air quickly.

Right now we just use heat and no flame and the swedish tests are accurate with what we are finding.