Is a hazardous rating required for this flowmeter?

[alo1]

I have an application where a flowmeter will be installed above a class 1 div. 2 boundry, well mostly. The bottom few inches of the meter will cross the hazardous bounry, but this part of the meter contains no exposed electronics and the electrical termination box is located more than 12" above the boundry.

Does the meter need to have a class 1 div 2 rating?

 

[rbalex]

Basically this is a case of ?you gotta draw the line somewhere.? My initial thought would be to raise the device out of the Division 2 location; otherwise, it would need to be identified as acceptable in the Classified location. BTW, how were you planning to handle boundary sealing requirements?

 

[alo1]

This is a gravity feed application and we are working with limited head so we cannot raise the flowmeter. We may be able to lower the slab it is supported on to effectively raise it though. Looks like we may have to.

Since the electronics (conductors used to generate the electromagnetic field) are essentially hermetically sealed indide the pipe, couldn't 501.15 B 2 Exeption No. 1 apply?

Exception No. 1: Metal conduit that contains no unions, couplings, boxes, or fittings, and passes completely through a Class I, Division 2 location with no fittings less than 300 mm (12 in.) beyond each boundary, shall not be required to be sealed if the termination points of the unbroken conduit are in unclassified locations.

I realize this isn't conduit, but the application is essentially the same.

The flowmeter does have an "Ex" Zone 2 rating, which I understand is not acceptable (see http://forums.mikeholt.com/showthread.php?t=103285) but how does 500.8 A apply?

500.8
Articles 500 through 504 require equipment construction and installation that ensure safe performance under conditions of proper use and maintenance.

FPN No. 1: It is important that inspection authorities and users exercise more than ordinary care with regard to installation and maintenance.

FPN No. 2: Since there is no consistent relationship between explosion properties and ignition temperature, the two are independent requirements.

FPN No. 3: Low ambient conditions require special consideration. Explosionproof or dust-ignitionproof equipment may not be suitable for use at temperatures lower than -25?C (-13?F) unless they are identified for low-temperature service. However, at low ambient temperatures, flammable concentrations of vapors may not exist in a location classified as Class I, Division 1 at normal ambient temperature.

(A) Suitability. Suitability of identified equipment shall be determined by one of the following:

(1) Equipment listing or labeling

(2) Evidence of equipment evaluation from a qualified testing laboratory or inspection agency concerned with product evaluation

(3) Evidence acceptable to the authority having jurisdiction such as a manufacturer's self-evaluation or an owner's engineering judgment.

FPN: Additional documentation for equipment may include certificates demonstrating compliance with applicable equipment standards, indicating special conditions of use, and other pertinent information.

Lowering the slab seems to be the answer by getting it out of the hazardous area altogether, but I am curious to see how the other areas of the code apply, or don't.

 

[rbalex]

It is difficult to see how 501.15(B) (2) Exception No. 1 would apply since the raceway is NOT passing completely through the classified location and the enclosure itself is, in fact, a box that is specifically prohibited by the Exception.

Section 500.8(A)(3) may possibly apply, but I doubt you could convince an AHJ; I?m pretty sure you wouldn?t convince me.

As I said, ?You gotta draw the line somewhere.? If you can lower the Division 2 envelope rather than raise the device, I would buy it assuming you could properly justify it.