Well, winter is here, and I have a cold-related issue to solve.

We have a spray booth, essentially outdoors. The sprayer arrangement uses pumps to spray paint on product as it passes through on a conveyor.

Outside of the immediate spray area are the supply lines - and the cold is making them freeze up. This area does accumulate overspray.

Any thoughts -pro or con- to using electrical heat tape to keep the lines and valves - all outside the tube in which the spraying takes place- from freezing? Would the type of heat tape matter?

Reno:
A quick reply is 'yes' heat trace will be OK. As to what type, depends on the o/s temp range, type of pipe, type of overwrap insulation, etc. Definately a 'regulated' heat trace. Look in WWGrainger catalog, or google.

Reno- I would suggest getting someone with the authority to classify the area do so and then design and wire accordingly. Article 516 addresses the spay area and openings within 3' of the spray area but you indicated that the heat tapes could be subject to overspray. I don't know if they make Listed heat tapes for a classified area. The main thing I would ask for, as an inspector, is that someone has classified the area so the engineer or electrician has a place to start their work.

Is the liquid paint flammable? Are the atomized paint / fumes flammable? Can the paint supply lines be insulated? What do they use for cleaning out the paint sprayers? Is it flammable? Is it reactive to certain materials?

John,
I'd tend to think that merely lagging the pipes would probably solve this problem.
I'm leaning towards the foam insulation that is used with Air Con/refrigeration piping.

Having said that, once you start getting into heat traces and what-not, you start needing things like intrinsically-safe supplies and explosion-proof connection boxes, even if it isn't inside the actual "hazardous area".
I'd try the lagging first.

Reno:
As I quickly said earlier...yes, it can be heat traced. Other members jumped in and asked most of the ?? I did not have time to get into this AM.

Basically, the ball is back in your court.

The 'overspray' situation could be mitigated (particles) by something as simple as boxing-in the pipes. As to the classification of the area surrounding the pipes, that's a lot of 'ifs'. Barriers, openings, etc., or is the paint a latex or other 'safe' formulation?

If you follow this link.... http://www.chromalox.com/productcat...=44&gclid=CKvx4-Pc9KUCFaVx5Qod4nXGow

You will find classified/hazardous location heat trace equipment, but watch your wallet!!

Thinking outside the box, so to speak, could they loop warm water through pex pipe, sistered to the paint lines and under the armaflex. The heater could then be outside the classified area

Actually Greg, that is a damned good concept, one that could even be taken into the spray-booth itself, as it uses no electricity.
Maybe you could send one of your water-cooled computers Reno's way!
Just kidding.

John, thanks for the link; I'll keep that in mind.

The operation is, for all practical purposes, outdoors. Sure, there's some structure around and over the area, but there are so many major -and necessary- openings that fresh air is abundant.

The 'paint' used has an extremely volatile and very flammable solvent. The paint itself - even in dried form- burns like rocket fuel. "Overspray" perhaps isn't the right term - perhaps it's better to say that enough particles get airborne, drift about, and settle on every surface that keeping the sprinkler heads functional is a challenge.

We did have the place catch fire once, and it was over in moments - a flash fire that consumed all long before any response could be mounted.

The material is pumped direct from its' shipping container to the spray jets, using flexible hoses, for a distance of perhaps six feet. These, and the air-powered valves at the spray assembly (technically outside the spray area) are what have been freezing up.

Really makes me wonder what they've been doing for the past twenty years when it got cold. I'm afraid to ask.

It is claimed that we are converting to a less flammable material, and that an entirely new booth will be installed next summer.

In the meanwhile, I've already made the point: we really need to have an engineering study performed, to define the classification of the areas.

How dry is the compressed air?

Yea, I was waiting for that shoe to drop ....

Let's just say that the plant has multiple issues with their compressed air service as well ... and well outside thew scope of the paint booth issue.

In a way it's ironic ... the easiest way to avoid these issues would be to enclose and heat the painting operation - yet doing so would really ratchet up the 'classified areas' issues. All that ventilation does have its' benefits.

How about a small point of service FRL dryer? (Filter, Regulator,Lubricator)

OK... then we still need to change the paint in the lines back into something more fluid than molasses. That is, our heating issue.

Build a small heated shed, away from the booth, with a tank of water. Circulate that next to the lines with a small pump and insulate the lines. Keep the paint in the shed too. It should stay warm until it hits the gun. The next question is how do they heat the spray area. I didn't think paint worked that well in cold weather.

Greg.,


I know you mention heated shed for paint storage however as far we know about the hazardous storage regulations and I have allready dealt one just not too long ago.,

I have to wired a exhaust fan and it have to be running 24/7 { the only time it will be off if all the pain barrel or any flameable liquid or items is removed complety from the shed }

Now the major issue with most paint I know with very flameable type they will have very low flash point the excat flash point will depending on what type of paint and mixure it will have in there.

You did hit a right idea with heated spray gun with hot water loop and I did try that with one industrial customer before and it work pretty well with hot water loop with insluating materals to keep the lines warm and not get freezed up.

There are some low tempture paint on market but IMO it don't always work very well with outdoor everoment unless it get heated air from air make up unit if that is in the indoor location.

But you will have to add a fuel cost factor to run heated make up air unit for spray booth.

My customer stated that he go thru about 4,000 liter of LP gaz in 3 weeks in super cold days

Merci.
Marc

The feedback has been most enlightening.

ECN has countless threads, where someone explains the great efforts required to correct some hack-job. Now, the more I think about it, this entire spray arrangement is just one big hack job.

"Well, it works" will say the sceptic. Actually, no, it doesn't - or I wouldn't have started this thread! I have also yet to get any decent explanation of the fire that once destroyed the place.

Production demands for a quick fix NOW. Management demands to -suddenly- become 'cost conscious.' An absolute refusal to look beyond the convenience of the moment .... let alone consider unlikely chance that Summer will change to Winter. (Heck, that's only happened nineteen times since the place opened - eighteen years ago).

Placing the paint vat in a heated area apart from the spraying area might help- MAYBE. With continual replacement of empty vats with full ones though, the sccess door will be open more often than not, and the door quickly becomes something else that can be broken- and we still have not eliminated the need to determine exactly what areas are 'classified' and which ones are not.

For all the Safety Manager's concerns about the non-rated heat tape, I can't help but suspect that in years past they simply rolled kerosene-powered space heaters in there, and blew hot air directly on the problem points. Or, perhaps, they used some of the 6-ft. "toasters" they have around the plant.

BTW, I was not involved in installing the heat tape; my involvement came after safety concerns were raised. I've pointed them to having a proper evaluation of the area made, and suggested the insurance carrier as a source for the expertise.

I sincerely hope they don't try to fob the 'engineering study' off on some newly graduated intern.

Reno:
Just an FYI, the 'people' that you could speak with are at the link I posted above. They were and are very helpful, and very knowledgeable. Just keep in mind you don't see 'Big Box' pricing (or product) at the link site.

I too like to think outside the box. Greg's concept is rather creative. And jacketing it in to protect the pex from getting caked in paint plus minimize heat loss. The pex wouldn't have to wrapped around the pipe like heat trace. Unlike heat trace though, the longer the hose is, the hotter the supply has to be. Glycol would have to be used otherwise the system would have to run 24/7 in the cold to keep from freezing like the pipes they are protecting. As I write this, I do see the price going up and up on the concept. They do make heat trace for hazardous areas. Heat trace does not lose heat like the pex would so that's a benefit of heat trace. I too would look at self regulating heattrace. I would contract a manufacturer's technical support to get more info on the application

Reno,

Nelson Heat Tracing Systems makes a Self-Regulating Trace, which is listed for Class I Division 1 & 2.(Product Family of Reference = "Limitrace").
It is more like a Tube, rather than the normal "Flat Romex-Looking" Cable.

Heat Trace installed in Hazardous (Explosion Hazard) Areas must have Sheath Temperature that do not exceed the ignition Temperature of the Hazardous Gas (or Dust), which is present.

Use a GFPE type Circuit Breaker for the Branch Circuitry (specify 30ma threshold, not the 4-6ma Class A types).
--- However, from the Flash Fire you described earlier in this Thread, if there is a Leakage (Current) on the Heaters, you will be notified by a sudden Ball of Flame long before the GFPE Breaker trips!


G.E., Siemens, and Cutler-Hammer (Eaton) have Low Voltage MCCB (10KAIC @ 120V) type GFPE Devices - in both Single Pole and 2 Pole Units; with Trip Settings of 15, 20 and 30 Amps.

They look exactly like a Class A GFCI Circuit Breaker, so be aware when you receive the devices from your Distributor!

For G.E., they come in standard Plug-In "THQ" or Bolt-On "THQB" frames.

For Siemens, they come in "BL" and "BQ" frames.

I cannot remember the C-H frame type.

Have fun!

-- Scott

Thanks, Scott. The project is, well, muddling along. With a recent increase in the temperatures provided by Mother Nature, the 'heat' is off this project .... until the next cold snap!

Regarding that fire .... you can engineer everything to the Nth degree- but all is lost when someone stands in the doorway with a cigarette. Oops.

Or uses a cordless drill from the big box store...

I'm using a PTC heat tape, [which needs no stat as it self regulates], to keep vegetable-oil fluid by tracing the oil lines. Similar problem, except that the oil forms crystals of fat rather than ice. These tapes don't get particularly hot & various grades are available. The main problems I encountered were that the stuff is not very flexible- it's difficult to manipulate to the route you want and has a minimum bending radius. The other problem was 'ending-off' and connecting to the power supply. My supplier provided a 'kit' [hahaha], comprising shrink-tube, self amalgamating tape and capping, which proved to be a nightmare demanding Astronauts skills, a hot air gun and 3 pairs of hands! End result looked clumsy and amateur despite my best efforts. The tube-runs also need an insulation tube over, as the power is just a few watts per foot. Add a necessary weatherproofing layer over that in your scenario and my crystal ball predicts a cornucopia of expletives issuing from the general vicinity of the electrician.

Alan:
I tend to agree with you regarding the language from the installer! I know I personally got very angry with heat trace.

My journeyman suggested using the "Big Orange" off the shelf, plug-in stuff which is a homeowners delight to install. Unfortunatley, .......no-can-do in the area we were working in.
(Wasn't veg oil)