Petrochemical refineries embedded with a chain of combustion and toxic hazards. The typical production derive products from the crude oil through series of process before the derivatives are delivered as product to the end customers. Continuous gas detection monitoring is compulsory in most cases by Occupational Health & Safety Administration (OSHA), the FM Approvals, the NFPA Fire Protection standards and some regional specific standards.
Figure 1, Production of Derivatives from the crude oil
Figure 2, Crude Oil Storage and the hazards
Crude oil storage tanks are the store the buffer feed stock for the refineries. The oil tanker unloads the crude oil through the terminal where the amount of oil unloaded and transferred has been measured. The loading and unloading process creates vibration that could trigger some minor leakages around the pipe connections. In the tropical weather, the gaskets and seals are also harden after years of services which are the source of leakage. Leakage around the crude oil storage tank and oil terminal is inevitable but it is important to monitor the potential gas cloud accumulation from the vapour of the crude oil residual. In the windy condition the gas cloud might have been disperse but it requires one fine stale day to create a perfect condition for combustion. That is also the reason why detecting gas cloud accumulation alone using LEL measurement is not sufficient and it is important to measure the present of gases in ppm. The LEL measurement will only show zero reading most of the time and in most cases the operator might doubt the gas detectors are functioning. The measurement in ppm will show reading in ppm even though there are some traces of gases present which could give an early indication of the present of combustible gases before the gas cloud accumulated. As part of the safety precaution any workers or operators entering the crude oil storage and terminal areas are required to wear personal gas detector either single combustible gas or four gases portable gas detectors detecting LEL, CO, H2S and O2.
Figure 3. A generic system architecture of a fire and gas detection system
A gas detection and monitoring system or fire and gas system should be open, scalable and easily configurable without depending heavily on the service provider. The hardware failure from one area should not be affecting the functionality of the complete system. Hardware redundancy might help to enhance the system uptime but segregation or segmentation can help to minimize the risk of complete system shut down.
Having a good range of portable gas detectors in the plant is also important for complimenting the LSS. The placement of the fix gas detectors might not be the most ideal and need to be evaluated from time to time. Semiconductor industry is quite a versatile industry where the tools placement and production layout might change due to new tooling installation. Portable gas detectors can further assist the plant operator for further assess the potential hazard due to gas leakage.