Different types of weighing systems are essential in many industrial and commercial applications. These scales are standard equipment needed for batch counting, parts counting, dispensing, and mixing ingredients. Because of the versatility of uses, weighing systems are also exposed to different working environments. While laboratories and similar mild applications subject weight scales to ideal working conditions, other applications expose weighing systems to hazardous elements. Factors such as extreme temperature, vibration, and contaminants may affect the performance of the equipment. As such, it is essential to take into account the working environment before choosing a suitable weighing system.
Weighing systems for hazardous applications
Many industrial processes, such as those that involve weighing corrosive materials, explosive products, and flammable chemicals, expose the weighing system to dangerous conditions. In these types of applications, each piece of weighing equipment needs to meet performance and safety specifications.
One of the ways to ensure that a weighing system meets these conditions requires to ensure that it has suitable protection to prevent explosion or fire. Explosions occur when there is enough dust, vapor, and combustible gas or oxygen to ignite. A weighing scale that does not have the proper protection may produce the energy which eventually triggers the explosion. A specially designed explosion proof scale is necessary when the application exposes the scale to hazardous gas and dust.
Methods used to make weighing scales safe for hazardous working conditions
Weighing systems are composed of various parts, including cables, controls, displays, and load cells. To minimize the risk of fire or explosion, these components need protection. Some of the methods used to make weight scales safe are:
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Intrinsically safe weighing systems
In achieving intrinsic safety, any electrical energy produced by the equipment needs to be limited up to a point where it can no longer ignite or trigger an explosion.
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Using an explosion-proof enclosure
This method involves putting electrical parts inside a housing that can contain potential internal explosions. By containing the explosion within the enclosure, the equipment will not ignite any combustible gases outside the system.
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Pressurized or purged enclosure
This method involves filling the sealed equipment enclosure with inert gas, which will prevent combustible gas, vapor, or dust from entering the system.
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Sand-filling
Any potential source of combustion or ignition is surrounded with fine sand. This method will prevent temperature arcs within the scale enclosure from igniting elements in the atmosphere.
Apart from these methods, weighing systems used in hazardous working conditions need to comply with international safety standards. In the US, the National Fire Protection Agency defines the codes and standards used, while most European countries comply with ATEX regulations. Hazardous conditions and areas are also determined depending on the types of hazardous materials present.
In general, any piece of equipment containing electronics should not be used in hazardous areas, but in instances when using one is unavoidable, the methods of protection discussed above will be applied so that scales may be safely used even if the conditions are less than ideal.