Single or two seal off fittings

[BJB48]

I am working on a methanol installation for a waste water treatment plant. Installation consists of a 4000 gallon tank, methanol feed pumps, sump pump, leak detection equipment etc. The tank and metering pumps and sump pump are located on a concrete slab. All pump VFD's, leak detection, truck grounding for fill station was relocated to a separate slab that will have an bus stop type roof and walls around all for the pump panels. Engineer specified a 10' boundry for class 1 div 1 from sump pump and metering pumps. All conduits into and out of area are PVC with 6"+ of concrete encasement more than 24" below finish grade. Transistion from PVC to PVC GRC is 2' below top of concrete. We planned on seal offs 12" above top of concrete for all conduits to equipment within the Class 1 Div 1 area. The rack's for the VFD's,etc. on the remote slab are a minimum of 12'6" from the closest conduit stub up in the classified area. County electrical inspector citing 514.8 and 515.9 says seal offs are required on both ends of the conduit runs. I contend that the single seal off within the classified area meets the 10' rule from boundry and is all that is required per 501.10. Any thoughts would be greatly appreciated.
Thanks,

Bruce

 

[raider1]

First off 514.8 is for Motor fuel dispensing facilities and 515.9 is for bulk storage plants so neither section would apply to a waste water treatment plant.

The applicable section would be 501.15(A)(4) for Class 1 Division 1 Boundary seals. The question becomes where is the Class 1 Division 1 boundary?

Chris

 

[BJB48]

Class 1 Div 1 Boundry

Class 1 Div 1 Boundry

Class 1 Div. 1 boundry is 10' from storage tank, feed pump and sump pumps. All VFD's and control equipment is a minimum of 12'6" from the closest piece of equipment.
Thanks for your response.
Bruce

 

[rbalex]

First off 514.8 is for Motor fuel dispensing facilities and 515.9 is for bulk storage plants so neither section would apply to a waste water treatment plant.

The applicable section would be 501.15(A)(4) for Class 1 Division 1 Boundary seals. The question becomes where is the Class 1 Division 1 boundary?

Chris

• That 4000 gallon tank may be in the scope of Art 515. We don?t know the details.
• I?m also curious about the Division 2 boundaries. Ya gotta hav?em somewhere. [Section 500.5(B)(2)(3)]

 

[raider1]

• That 4000 gallon tank may be in the scope of Art 515. We don?t know the details.
• I?m also curious about the Division 2 boundaries. Ya gotta hav?em somewhere. [Section 500.5(B)(2)(3)]

True, the tank could fall under Article 515.

I agree that we need more details on the locations of the boundaries.

Chris

 

[BJB48]

Class 1 Div 1 Boundry

Class 1 Div 1 Boundry

Bob/Chris,
Thank you for your repsonses and believe me that I am not trying to be a smart a--, just trying to understand. I read and re-read 500.5 B 2&3 which you referenced and tried to understand why there has to be a class 1 div 2 location wherever there is a class 1 div 1 area. In this case, as I said previoulsy the specified boundry is a 10' envelope from any of the pumps or devices that are located within the methanol transfer or loading area where there could be a possibility of any escape of the methanol. All electrical equipment is located outside of this zone by the dimensions I originally gave, i.e. 12'6" minimum. There is no methanol piping or any means of release of any liquid or vapors ( this is all within the class 1 div 1 zone). If this is the case it does not meet any of the qualifications of 500.5 B (2) (3) as this entire installation is outdoors and unlimited free air (although not positive pressure).
Again,
Thanks for your input.
Bruce

 

[rbalex]

Subsection 500.5(B)(2)(3) I was citing is below.

500.5Classifications of Locations
?
500.5(B) Class I Locations. Class I locations are those in which flammable gases, flammable liquid?produced vapors, or combustible liquid?produced vapors are or may be present in the air in quantities sufficient to produce explosive or ignitible mixtures. Class I locations shall include those specified in500.5(B)(1) and (B)(2).
?
500.5(B)(2) Class I, Division 2. A Class I, Division 2location is a location
...
500.5(B)(2)(3) That is adjacent to a Class I, Division1location, and to which ignitible concentrations of flammable gases, flammable liquid?produced vapors, or combustible liquid?produced vapors above their flashpoints might occasionally be communicated unless such communication is prevented by adequate positive-pressure ventilation from a source of clean air and effective safeguards against ventilation failure are provided.
?
[Underline mine]

Basically, in an open air situation, if you have a Class I, Division 1 location you will have a Division 2 location adjacent to it. You noted yourself," ... this entire installation is outdoors and unlimited free air (although not positive pressure).?

Fundamentally, in open air, you cannot have a location that is classified hazardous under normal conditions (Division 1) next to a location that is never hazardous (unclassified). In absence of a physical barrier between Division 1 and unclassified, there must be a Division 2.