What should you know about calibration in hazardous areas? A lot. This blog article will discuss calibration in hazardous areas and what you need to be aware of prior to entering a hazardous area with calibration equipment.
Hazardous Area Defined
First of all, what exactly is a hazardous area? It’s defined as a place, whether indoors or outdoors, which may contain flammable substances—gas, liquid, vapor, or even dust. This hazardous area may contain a flammable substance at all times or most of the time, but can also be only in specific instances.
Preventing an Explosion
We already touched briefly on flammable substances in hazardous areas; next up is how to prevent an explosion from happening. More often than not, when it comes to a possible explosion, it is impossible to eliminate the flammable substance itself. The more doable solution is to eliminate the source of ignition that could trigger an explosion when it comes in contact to the flammable substance. Most of the time, it’s easier remove spark or heat from the equation.
Let’s expound more here: in hazardous areas, an explosion is possible of all three conditions are met; these three conditions are the flammable substance (like fuel, for instance), air (or more specifically, oxygen), and heat (or the source of ignition). The easiest of these three conditions to eliminate, as we’ve already discussed, is the source of ignition.
Looking back at some of the first hazardous areas throughout history
The first hazardous areas were actually discovered in the early coal mines; coal dust and the methane that is absorbed in coal mines both created a hazardous area. This and the fact that lighting in the mines in those early days consisted of candles and torches led to many accidents.
So were accidents eliminated when lighting with the use of fire (candles and torches) was replaced with electricity? Good question. But sadly, the answer is, still, no. Why? Even though miners were already starting to use electrical equipment, accidents still happened because—you guessed it—sparking and heating still happened due to sparking and heating of electrical equipment. Later, design standards were eventually developed in order to guide the design process to prevent the sparking and heating of electrical equipment.
This is the first “intrinsically safe” electrical equipment, which led the way to the standards being compiled for equipment that is used in hazardous areas today.
Common Industries with Hazardous Areas
The most common industries that have to deal with hazardous areas include oil refining, paint shops, energy production, offshore and onshore gas and oil, refining, mining, and yes, even food and beverage industries.
Of course, even some seemingly safe industries may have to deal with hazardous areas. Depending on the industry, some plants may have large hazardous areas, whereas others might have only small sections that can be classified as hazardous areas.
A Look at Flammable and Combustible Liquids
Discussing hazardous areas will naturally lead to what liquids are flammable and combustible. So what are flammable and combustible liquids, anyway? They are, generally speaking, liquids that can burn—simple as that. These liquids may be solvents, cleaners, chemicals, paints, and of course gasoline and diesel fuel.
However, to be precise, flammable and combustible liquids do not burn in their entirety; rather, it is the vapors that burn. To be more precise, it is the mixture of the vapors and air that actually burns.
How Can Safe Calibration in Hazardous Areas Be Done?
First things first, “intrinsically safe” equipment should be used. Intrinsically safe equipment is designed for any situation; it will not provide enough energy to generate sparks and excessively high surface temperatures—even in the case of a faulty device, for instance. As its name suggests, the equipment is designed to, well, be intrinsically safe.
A Look at Hazardous Zones Classification
Let’s take a look at the classification of hazardous zones. This zone classification specifies how likely it is for a certain flammable substance to occur in the atmosphere in a certain area.
|Zone (gas, vapor)||Zone (dust)||Description|
|Zone 0||Zone 20||Area in which an explosive
substance in the atmosphere
is present continuously or for
long periods or frequently.
|Zone 1||Zone 21||1 Area in which an explosive
substance in the atmosphere
is likely to occur in norm
|Zone 2||Zone 22||Area in which an explosive
substance in the atmosphere is
not likely to occur in normal
operation but, if it does occur,
will persist for a short period
Using the Right (and Safe) Calibration Equipment That Is Suitable for the Corresponding Environmental Conditions
In a nutshell, when doing the calibration in hazardous areas, it is important to make sure that the equipment used for calibration is actually suitable for the environmental conditions where it will be used. For instance, the safe operating temperature wherein an equipment is used in a plant: in, say, wet and dusty conditions, the protection rating of the equipment casing needs to be considered. In addition, different protective techniques may also require different classification on the casing.