Explosion-Proof Guidelines - Scientific Systems, LLC

Scientific Systems has been building HVAC, pressurization, and chiller units for hazardous (classified) areas since , and is the oldest and manufacturer in the industry. Because we manufacture the units, we will be here to assist with any questions you have post-installation.

MAM supply professional and honest service.

“Explosion Proof” is only a generic term. When applied to equipment it does not by itself assure that the item is safe to use in a hazardous location. Required are additional code designations as issued by agencies in the United States, Canada, Europe and other parts of the world.

For more information, please visit explosion proof control panel.

In North America and many other countries explosion-proof electrical equipment must conform with NFPA 70 National Electrical Code (NEC). Western Europe and some other countries work with CENELEC standards or accept equipment certified under either system.

An “Explosion Proof” designation under the NEC must include a “Class”, a “Group” and a “Division”. Class I refers to gases, Class II to dusts, and Class III to fibers and flyings. Groups relate to the ignitability of the material. Two Divisions are defined as outlined below.

The company is the world’s best Explosion-proof Handle supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.

One of my customer asking an explosion proof HMI + PLC panel for LPG storage tank hazardous zone. The HMI to be for both controlling (by hand touch) and monitoring. The PLC and HMI must be Siemens brand.


What is the best way to do/get that? Ask for the hazardous area location drawing and where they want to install it along with the risk assessment.

If it's not in a Zone 2, then can't be done.


If it's in a zone 2, contact someone that can design that for you to be certain of what you're doing. I think it could be done with a rated, purged enclosure, but the HMI would have to be inside the enclosure, and you view it via window. Need to check with your local experts.

The enclosure is purged for a set period before power is applied, once power is applied, it pressure drops below a minimum value, the power is removed before explosive vapor can enter.

You want to make sure what ever system you use is approved/certified by a third party. In the US, this would be FM or other authority. It's going to be expensive.


I think it would be more cost effective to have the PLC in a safe area and use Profibus PA (intrinsically safe) for field devices. The HMI would still be a challenge.