Optimizing Hazardous Area Classification with Improved

Process Inputs

Optimizing Hazardous Area Classification with Improved Process Inputs

Brief Summary of Hazardous Area Classification methodology used and influence of Process inputs.

New calculation methods used to improve Process inputs.

Case studies to illustrate advantages.

Conclusion Importance of closer cooperating with other disciplines.

SummaryHazardous Area Classification Methodology

Identify flammable products present in plant or unit and determine physical properties.

SummaryHazardous Area Classification Methodology

SummaryHazardous Area Classification Methodology

Identify flammable products present in plant or unit and determine physical properties.

Identify and classify all potential points of release. Provide operating conditions for release points.

SummaryHazardous Area Classification Methodology

SummaryHazardous Area Classification Methodology

Identify flammable products present in plant or unit and determine physical properties.

Identify and classify all potential points of release. Provide operating conditions for release points.

Determine extent and Zone classification of each release point based on product properties, classification of release point and operating conditions.

SummaryHazardous Area Classification Methodology

SummaryHazardous Area Classification Methodology

Identify flammable products present in plant or unit and determine physical properties.

Identify and classify all potential points of release. Provide operating conditions for release points.

Determine extent and Zone classification of each release point based on product properties, classification of release point and operating conditions.

Generate area classification drawing that can be used by design engineers , maintenance and plant personnel for determining electrical equipment and instrumentation requirements.

SummaryHazardous Area Classification Methodology

Influence ofProcess Inputs

The radii calculated is dependant on the molecular mass of the product, lower explosion limit, size of the release point and operating pressure.

The calculated extent or radius of the release will increase with a decreasing lower explosion limit.

The calculated extent or radius of the release will increase with a decreasing molecular mass.

Using the worst case combination of lowest molecular mass and lower explosion limit leads to over conservative radii calculated

New Process Input Calculations

The improved calculation methods uses Le Chateliers principle to calculate the lower and upper explosion limit of a mixture of components.

New Process Input Calculations

The improved calculation methods also correct the lower and upper explosion limit for atmospheric pressure and allows for the effect of inert gasses to be considered.

Actual Case Studies

Case Study 1: Determining if the gas sample is flammable

The composition of a gas sample was provided as follows:

Actual Case Studies

Case Study 1 : Determining if the gas sample is flammable

The composition of the mixture that was provided was used to calculate the lower and upper explosion limits from the new calculation method. The results obtained are as follows:

Actual Case Studies

Case Study 1 : Determining if the gas sample is flammable

The actual concentration of flammable components can be seen to be lower than the lower explosion limit of the mixture.

The lower explosion limit of the mixture will not be reached. The mixture is not considered flammable.

Previously, this gas was classified as being flammable. With the improvement in calculation methods, the classification of this gas was removed

Actual Case Studies

Case Study 1 : Determining if the gas sample is flammable

Conclusion:

1. The concentration of the flammable components in the gas is too low to reach the lower explosion limit and therefore, the gas will not be classified as flammable.

2. The improved calculation methodology will result in a less conservative and more accurate extent radius being calculated.

Actual Case Studies

Case Study 2 : Determining at what ratio of gas to air will the cylinder gas be flammable.

The following table reflects a gas stored in cylinders:

Actual Case Studies

Case Study 2 : Determining at what ratio of gas to air will the cylinder gas be flammable.

The following table indicates the lower and upper explosion limits that were calculated corrected for atmospheric pressure:

Actual Case Studies

Case Study 2 : Determining at what ratio of gas to air will the cylinder gas be flammable.

If the gas from the cylinder is released into air, it will be flammable from a composition of 10% - 30% of gas in air.

With the previous method of classification, the lower and upper explosion limits for methane (5% - 15%) would have been assumed for the lower and upper explosion limits of the mixture. Which would have resulted in a less accurate extent being calculated.

Actual Case Studies

Case Study 2 : Determining at what ratio of gas to air will the cylinder gas be flammable.

Conclusion:

1. The lower and upper explosion limits will provide a more accurate extent radius for a gas release than previous methodology.

Conclusion

The new calculation methodology will translate into a more accurate and less conservative approach to hazardous area classification with regards to lower and upper explosion limits