Explosion-Proof Scales & Hazardous Area Weighing Solutions

Explosion-proof scales or hazardous area scales are engineered specifically to minimize the risk of explosion when production materials and processes create potentially explosive environments. For example, in Zone 1 classified areas where explosive gas atmosphere is likely to occur during normal operation, it is important to have equipment with fully contained electronics so that there is no risk of sparking or heat accumulation that could set off an explosion. Explosion-proof electrical equipment can contain an explosion and extinguish the flame. When looking for scales for hazardous zones, ensure you find a trusted supplier who can prove intrinsic safety of their equipment.

METTLER TOLEDO has a wide variety of intrinsically safe scale solutions for hazardous zones. From hazardous area bench scales, hazardous area floor scales, hazardous area load cells - and more. Find your perfect hazardous area scale today, and ensure safe, accurate and efficient weighing.

Intrinsically safe technology prevents explosions by ensuring that the energy transferred to a hazardous area is well below the energy required to initiate an explosion. As such, it is restricted to electrical apparatuses and circuits in which the output or consumption of energy is limited. Intrinsically safe systems enable equipment to be used without risk of igniting any flammable gas, dust or fibers that may present in hazardous areas. Our hazardous area scales are intrinsically safe.

The flameproof protection method is based on the explosion-containment concept, in which the explosion is allowed to take place, but it must remain confined in the enclosure that is designed to resist the excess pressure the internal explosion causes. A flameproof system is generally considered somewhat simpler to design than an intrinsically safe system, as it doesn’t require completely new equipment design. However, it is generally more expensive to install because of the high cost of running field wiring inside a conduit, which must be sealed between the safe and hazardous areas. It is also often physically larger and much heavier than an intrinsically safe solution. Flameproof equipment is also more difficult and time-consuming to maintain because either the area must be known to be non-hazardous or the equipment must have the energy drained before covers can be removed. Hot permits are required to perform maintenance work on these systems. Further, when covers are re-installed, extra care must be taken that fasteners are precisely torqued to specified values

For more information, download the Hazardous Area Competence Guide.

Explosion-proof equipment is designed so that should an explosion occur, then it will be contained with an adequate enclosure.  Intrinsically safe equipment is designed to limit the energy of sparks and surface temperature in order to inhibit an explosion from occurring. Our hazardous area scales are intrinsically safe.

Class I Division 1 hazardous areas are locations that are defined by the National Electrical Code (NEC) Handbook with articles 500, 501, 502, 503, 505, and 506.  Class I locations are those in which flammable gases or vapors are present in the air in quantities sufficient to produce explosive or ignitable mixtures (NEC 501).  Division 1 is a subset of Class I and is classified as an area where the explosive or flammable gases, vapors or liquids mentioned above can exist under normal, everyday operating conditions.

Zones are classified by the National Electric Code (NEC) and described in article 505.  One characteristic of Zone 2 areas is when ignitable concentrations of flammable gases or vapors are not normally present but could be present in certain cases that are clarified in the NEC standards.  Zones are also classified by ATEX 1999/92/EC Directive based on the frequency and duration of the occurrence of the explosive atmosphere.  Zone 2, according to ATEX 1992/92/EC Directive, is when an explosive atmosphere is likely to occur infrequently or for short periods of time.

For explosion-proof wiring, which is required in Div 1, conduits and gaskets are required.  They are used to isolate the circuit from hazardous gases.  In sequences, a gasket is attached to the conduit as a fixture into which you can pour sealant. This setup prevents the gases from flowing into the cable conduit and entering uncontrolled areas.