Equipment in Potentially Ignitable Atmospheres
Working with ignitable vapors, dusts and fibers can drive requirements for specially designated areas or zones, which then require specifically rated equipment. R&D laboratories often have some flexibility when handling such materials, but manufacturing or production type environments are almost certain to have such requirements. Two common designating terms for such areas/ratings are HAZLOC (Hazardous Locations) found mostly in North America and ATEX (Atmosphères Explosives) found mostly in Europe. The International Electrotechnical Commission (IEC) provides standards for certification (IECex) in an attempt provide globally accepted standards for improved safety in such designated areas. US, Canada and Europe use adaptations of the IECex standards, though the US and Canada also still recognize their traditional methods.
Determine What is Needed
When a customer asks Parr for equipment rated ATEX or HAZLOC, they may first be asked; “Why?”. The answer may not be as predictable as one might think. The rating requirements could be from the handling of gasses or solvents used in the Parr equipment or it could be that the equipment will be installed in an already classified area. This is why subsequent questions may be asked, such as:
- Does the area have a specific classification?
- What ignitable vapors are present in the area?
- Is the ignitable atmosphere always present?
The area classification will direct Parr engineers to suitable equipment ratings that meet the area classification. However, it’s not uncommon for requests of specifically rated equipment even when other equipment ratings are defined as suitable by local authorities. An example of this is in a Class I Div 2 classified location, a non-incendive rated sensor is acceptable by the governing body, but the user’s facility manager or Authority Having Jurisdiction may only accept intrinsically safe sensors.
When an area is not officially classified the following questions may be asked:
- What vapors are of concern?
- How often is the area expected to have ignitable concentrations of such vapors?
- Do you require any specific equipment ratings?
This information will help Parr’s staff determine what equipment can be offered and may identify any devices that are exceptionally challenging to procure based on the operational conditions, such as circulators for temperatures above 250 °C.
There are some common misconceptions and misused terms associated with hazardous locations that are worth mentioning.
The term “Explosionproof” is often generically used to represent any rated equipment used in such areas, but the term is actually a specific type of protection. Explosionproof protection, similar to Flameproof for ATEX and IECex protection methods, indicates that the equipment is designed within an enclosure that will contain an explosion if it occurs. This prevents the explosion from igniting the atmosphere around the equipment. Wiring boxes, Motors and some Sensors are commonly available with Explosionproof or Flameproof ratings.
A common misconception is that any equipment that handles ignitable vapors must be rated or it is assumed that it is already rated. This is not true as the standards mostly focus on if vapors are present in ignitable concentrations with air at atmospheric conditions. For example, mass flow controllers for hydrogen gas are often sold without hazardous location ratings. Rated versions are used for protection related to the surrounding atmosphere and not the pathways of the hydrogen gas internally.
Here to Help
Navigating HAZLOC/ATEX requirements can be daunting, though we have found that only a small amount of projects that start out with stringent HAZLOC/ATEX requirements actually end up built that way. Often, it seems, the end user will integrate other means of reducing risks such as: ventilation methods (fume hoods), gas sensors/automatic shutdowns, or specific operating procedures/risk assessments. Contact Parr’s Technical Service and Engineering teams to discuss available options for such specially rated components.