Combustible vapors require special equipment

Striking a match in an environment that contains combustible gas is nothing short of dangerous – personal injury and property damage are likely consequences. Improperly calibrating an instrument in this hazardous environment can be almost as dangerous.

The materials and fluids used in some processes can be hazardous in the sense that they can ignite or explode. For example, hydrocarbons in mines, oil refineries, and chemical plants are flammable and are typically contained within vessels and pipes. If this were truly the case, an external flame would not ignite the hydrocarbons. However, in many locations, leaks, abnormal conditions, and fluid accumulation may allow hydrocarbons to be present such that the flame could ignite the hydrocarbons with disastrous results.

Hydrocarbons and other flammable fluids are not limited to the petroleum and chemical industries. For example, combustible fuels, such as natural gas, are used in all industries, including agriculture, food, pharmaceuticals, power generation, pulp/paper, water/wastewater, universities, retail, and in the home.

In addition, many materials and fluids used in seemingly “safe” industries are themselves flammable. Even seemingly safe water treatment systems use combustible materials such as chlorine in their processes. This means that certain areas of a water treatment plant may well be considered hazardous. Similarly, certain areas of food plants, such as reactors that hydrogenate oils, may pose hazards as well. Therefore, it is important for plants to examine their processes and identify hazardous locations so that the proper instruments are selected, installed, and maintained in accordance with practices that are appropriate for the hazard.

Equipment Requirements in Hazardous Locations
Protection requirements for hazardous locations vary according to the type of material present, frequency of the hazard, and the protection concept applied.

The intensity with which various vapors can combust is generally different. Groupings (IEC 60079-10) in order of decreasing ignition energy (with an example of a gas in the group) are:

The hazardous area classifications (IEC 60079-10) in order of decreasing frequency are:

Intrinsic Safety (IS) is the most common protection concept applied to calibrators that are used in hazardous locations. In general, the IS concept is to design the calibrator such that it limits the amount of energy available such that it cannot ignite a combustible gas mixture. Adding the applicability of IS designs to various hazards in the previous table yields:

In addition, a hot surface temperature on a device can cause ignition. Temperature classes limit the maximum surface temperature between 450˚C (T1) and 85˚C (T6).

Beamex calibrators for hazardous locations are designed and certified for Ex ia IIC T4 hazards per the ATEX Directive and are applicable to all vapor hazards where a temperature class of 135˚C in a 50˚C ambient is acceptable. As such, they can be used for the overwhelming majority of applications where a vapor hazard is present.

Calibration Solutions for Hazardous Locations
Instruments designed to measure flow, level, pressure, temperature, and other variables designed in hazardous locations are generally used to monitor and control the process. In some applications, it is practical to remove these instruments and calibrate them on the workshop with a calibration test bench. This is usually not the case, which means that many instruments are calibrated in the field. Fortunately, there are calibrators that are specifically designed to operate safely in rugged environments and hazardous locations.

The Beamex MC5-IS is a portable, intrinsically safe, multifunctional calibrator that has modules which can accommodate wide ranges and many types of pressure, RTD, thermocouple, voltage, current, pulse, and frequency measurements.

The Beamex MCS100 modular calibration system is a test bench and calibration system for workshops and laboratories that incorporates the functionality of the MC5 multifunction calibrator and can measure/generate additional parameters such as precision pressures. The ergonomic design and modular construction allow the user to select the necessary functions in a cost-effective manner.

The Beamex CMX software integrates calibration management by allowing efficient planning and scheduling of calibration work. It not only alerts you when to calibrate, but also automatically takes data, creates documentation, adheres to cGMP regulations (21 CFR 11), and tracks calibration history. This software generally makes calibration work faster and easier and is designed to integrate into management systems such as SAP/R3 and Maximo.