Weighing in hazardous areas
Explosion Proof, Purged, Intrinsically Safe Systems,
Intrinsically Safe Environment
Explosion Proof, Purged, and Intrinsically Safe Systems
Explosion Proof
What is an explosion-proof indicator? It’s simply a digital weight indicator enclosed in a special case. The purpose of an explosion-proof indicator is not, as the name suggests, to protect the indicator. Instead, the case prevents any explosion WITHIN the case from causing subsequent fire or explosion in the surrounding atmosphere.
For example, in a grain elevator application, combustible dusts (Class II hazardous atmosphere) may be present. A spark in a non-explosion-proof indicator could ignite an elevator-wide explosion. However, with and explosion-proof indicator, the spark (or even an explosion) is contained within the case. The hazardous atmosphere cannot be ignited, and the elevator is protected.
Purge
Purged systems are ideal for hazardous environments and use positive pressure to prevent particles, gases, and fibers from entering the controller enclosure. As an added safeguard, a differential pressure switch automatically cuts off power when the pressure falls below the acceptable level. Type X, Y, and Z purging hardware is available that meets National Fire Protection Association (NFPA) article 496 guidelines.
The three configurations are as follows:
- Type X Pressurizing:
- Reduces the classification within the protected enclosure from Division 1 to Safe.
- Type Y Pressurizing:
- Reduces the classification within the protected enclosure form Division 1 to Division 2.
- Type Z Pressurizing:
- Reduces the classification within the protected enclosure from Division 2 to Safe.
Intrinsically Safe
Intrinsically safe load cells and safety barriers take the explosion-proof principle a step further. Intrinsic safety ensures that the indicator’s electrical wiring and components are, by design, incapable of releasing enough energy to ignite flammable or combustible atmospheric mixtures in their most easily ignitable concentrations. In short, an intrinsically safe device eliminates the conditions for an explosion no matter what the circumstances.
Intrinsically safe design combined with explosion proofing provides a protection system that gives the user unbeatable safety while offering the cost-efficiency of on-site weight indication.
Creating an Intrinsically Safe Environment
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MTI carries a full line of Intrinsically Safe and Explosion Proof Indicators, Junction Boxes, and Load Cells. All meet full Factory Mutual Approval for Intrinsically Safe applications. Determination of systems classification to any hazardous environment must be ultimately made by the customer and local authorities.
If you are unsure of the design criteria involved in determining how your application applies to intrinsic safety guidelines, ask our engineers. We maintain up-to-date National Standards on all relative information and guidelines to intrinsic safety. MTI has the experience necessary to guide you through the process of meeting the stringent specifications which will satisfy your insurance underwriter. As a provider of such equipment, we leave no details unchecked. All systems go through a complete verification process prior to shipment. You're assured that the equipment you receive will meet the exact requirements that you have specified. Call one of our hazardous area application specialists for immediate answers to any of your hazardous area weighing questions.
