need help with penetrating wall from paint mixing room.

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bullheimer

Senior Member
Location
WA
This Mixing room is attached to, and came from, a premanufactured automotive paint booth. All my owner keeps saying is that it has to be explosion proof. i am not even sure what catagory it is. i guess i need to read up. There is a continuously running 24/7 exhaust fan in the ceiling that's pretty big. I have to run power into this room for the mixer motor thru the ceiling and the fire supression guy just drills a hole and puts a standard looking grommet around his pipe and leaves. I am wondering how that is Kosher. I have to run a pipe down to the motor and then liquidtite into it, which i guess is all good. But i am wondering how a circuit card for the display board can have it's back be open and be called intrinsically safe?

Also there is a scale to weigh the paint that has a cord on it that is supposed to be run outside the room to plug into an outlet.

I have never had to wire up anything like this before. It has double metal wall panels. A control panel has a cable with a plug in connection that attaches to the inside wall. Nothing has any place to pour powder or put putty. any help as to what type of catagory of hazardous location this is, or what is normally done with these kinds of rooms would be a great help. Are there substances to put into the ends of liquid tite like duct seal, or does there have to be an explosion proof fitting going into the motor first, i'm just not up on this paint booth stuff. if it was a commercial garage, theres a 3 ft up from the floor explosion proof requirement, that i think goes away with continuous ventilation. i don't think that applies to this room tho. the motor and scale both are going to be within 3 ft of the floor anyway.
 
kwired

kwired

Electron manager
Location
NE Nebraska
bullheimer said:
This Mixing room is attached to, and came from, a premanufactured automotive paint booth. All my owner keeps saying is that it has to be explosion proof. i am not even sure what catagory it is. i guess i need to read up. There is a continuously running 24/7 exhaust fan in the ceiling that's pretty big. I have to run power into this room for the mixer motor thru the ceiling and the fire supression guy just drills a hole and puts a standard looking grommet around his pipe and leaves. I am wondering how that is Kosher. I have to run a pipe down to the motor and then liquidtite into it, which i guess is all good. But i am wondering how a circuit card for the display board can have it's back be open and be called intrinsically safe?

Also there is a scale to weigh the paint that has a cord on it that is supposed to be run outside the room to plug into an outlet.

I have never had to wire up anything like this before. It has double metal wall panels. A control panel has a cable with a plug in connection that attaches to the inside wall. Nothing has any place to pour powder or put putty. any help as to what type of catagory of hazardous location this is, or what is normally done with these kinds of rooms would be a great help. Are there substances to put into the ends of liquid tite like duct seal, or does there have to be an explosion proof fitting going into the motor first, i'm just not up on this paint booth stuff. if it was a commercial garage, theres a 3 ft up from the floor explosion proof requirement, that i think goes away with continuous ventilation. i don't think that applies to this room tho. the motor and scale both are going to be within 3 ft of the floor anyway.
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I don't know I can answer every one of your questions - some maybe just need more information to be able to answer as well.

Some general basics of "explosion proof" wiring though - we don't design such systems to prevent ignition of the hazardous gas - we design the system to contain an explosion when one occurs.

Ventilation can possibly change the classification - there may be some sensing and interlocking required to prove ventilation before you can energize something under the change in classification area though. You don't want to get involved in determining that classification though, leave that to design engineers, insurance companies, or others that may be willing to classify it - you don't need the liability if not trained to classify it, and if you are trained to do so - charge accordingly.
 
rbalex

rbalex

Moderator
Staff member
Location
Mission Viejo, CA
Occupation
Professional Electrical Engineer
bullheimer said:
close enough to mixing rooms?
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,
Well, you may need to study Section 516.3 a bit, but there are plenty of references to classifying locations adjacent to spray areas. If the mixing room is instead isolated from the spray booth or there are large quantities of flammables involved in mixing, then the classification would depend on the quantities handled and ventilation rates and you would need to refer to NFPA 30. It could depend on both Article 516 and NFPA 30.

I'm surprised the booth manufacture hasn't provided documentation. It's pretty common. Without knowing the details of the installation and processes involved, it's impossible to determine from a narrative alone.
 
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bullheimer

Senior Member
Location
WA
will do. lots of so called intrinsically safe stuff like the scale and a control module for and, the mixing motor. putting explosion proof fittings on the wall penitrations. really gotta read that article. been working about 12-13 hrs a day. last thing i want to do is either go online or read. ugh read? blah.
 
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