Part Three: UL698 - Understanding Underwriters Laboratory (UL) Certifications, Use in Hazardous Locations
At Palmer DCS, we are proud of our UL certifications. They help us demonstrate to our customers our commitment to making high quality industrial control panels (ICP) they can count on.
Most people have seen a UL mark, but they are less familiar with the wide range of different certifications available from UL. We want you to get to know our certifications, understand the requirements for attaining them, and see what that level of quality means for our customers.
Last time, we set out to clear up confusion relating to the NRBX subcategory of UL 698A. Today we want to take a closer look at a related subcategory which also causes a lot of confusion.
Like NRBX, UL 698 NNNY deals with ICPs that relate to operations in hazardous areas. Here’s what makes them different: NNNY governs ICP located within hazardous areas. As we discussed last time, NRBX is designed for ICPs that govern operations within hazardous areas but are themselves located in a non-hazardous area.
So, for part three of our in-depth look at our UL certifications, we’re going to examine UL 698 NNNY, what constitutes a hazardous area, and some of the ways panels can be designed to earn this certification.
The Advantage of UL 698 NNNY Certification
We’ve said it before, and it applies here: installing a UL certified panel is the best way to give yourself peace-of-mind. You don’t have to worry about an inspector tagging your panel, and shutting down your operations until you can make the necessary repairs. But when it comes to NNNY, there’s another, more fundamental concern that makes the certification all the more important: safety.
An error in an intrinsically safe panel can be bad, but an error in a panel used in a hazardous location can be catastrophic. Choosing a certified panel means you rest easier and can maintain consistent and safe operation.
What Constitutes a Hazardous Environment?
In our previous post, we outlined many of the different classes, divisions, and groups that factor in to categorizing a space as hazardous or non-hazardous. Since only a few of those categories apply here, we’ll only focus on those today.
Classes define which sorts of potentially dangerous substances are present in a given space. NNNY applies to ICP with a Class 1 rating. Class 1 means that flammable gas, liquid, or vapor is present in a given area.
Groups are a subcategory of Classes that set out precisely which substances tend to be present in that area. The groups that apply to Class 1 are:
- Group A: Acetylene
- Group B: Hydrogen
- Group C: Cyclopropane, ethyl ether
- Group D: Acetone, butane, propane, hexane, natural gas fuel oil
Division denotes how regularly hazardous conditions are present in a given area. Division I applies to areas where flammable or combustible concentrations exist under normal circumstances, or are likely to exist under other circumstances. Division II is for areas where those concentrations exist under abnormal circumstances, or are not likely to exist under other circumstances.
As evidenced by the narrower range of circumstances in which it can be applied, the NNNY certification is far more stringent than the NRBX. With the potential dangers involved, this is more than understandable, it’s vital.
What it Takes to Build an NNNY-Compliant ICP
There are three different methods that can be employed to ensure an ICP meets the rigid standards of NNNY certification.
Explosion-Proof Panels (NEMA Type 7 Panels) may sound like they’re designed to withstand an explosion from the outside. In fact, it’s the other way around. These panels are designed to contain any explosions, sparks, or flares that occur within the enclosure. These ICP are designed for use in locations matching the classes, groups, and divisions defined above. (Class 1, Division 1 & 2, Groups B,C and D only)
Non-Incendive Panels employ circuits and other components which are designed to be incapable of starting a fire, igniting the specified mixture of flammable gas or vapor and air. Since these are specialty components, they are each UL-listed for hazardous locations ( Class 1, Division 1 & 2, Groups A,B,C and D.)and classified as non-sparking equipment or hermetically sealed devices.
Also, the difference between “incendive” and “incendiary”? An incendiary is a device intended to start a fire, an incendive is merely capable of doing so.
- Purged and Pressurized Panels supply air (or other non-flammable gasses) to an enclosure at sufficient volume to maintain positive pressure inside the enclosure. Doing this purges the enclosure of flammable gas or vapor, combustible dust, or ignitable fibers. This allows panels to be built for hazardous locations without needing internal parts that meet non-sparking or hermetically sealed qualifications.
There are two types of purge units, each one fitting a particular situation. The type “X” purge panel is used for a Class 1, Division I Groups A, B,C and D. Type “Z” is used for Class 1, Division II Groups A,B,C and D..
There is a lot to understand about the specifics of UL certifications for enclosed ICPs relating to hazardous areas. We hope that both this guide and our previous one have given you a little more insight.
If you have questions about ICPs, UL certifications, or Palmer DCS in general, we would love to have the chance to answer them for you. Feel free to reach out to us by emailing info@palmerdcs.com.
And thanks for letting us tell you more about what we do.