The Challenge: Ensuring Safety During Flammable Liquid Handling
During the storage and handling of flammable liquids, implementing robust safety solutions is critical to prevent the build-up of static electricity, which poses significant risks.
This case study illustrates how Newson Gale assisted a customer specializing in resin production, enhancing their employees' safety through effective static control.
A comprehensive HAZOP (Hazard and Operability Study) analysis revealed a crucial need to simultaneously ground and monitor multiple metal containers during processing to effectively reduce the risk of static charge accumulation.
The Solution: Earth-Rite® MULTIPOINT II for Process Safety
Newson Gale provided the Earth-Rite® MULTIPOINT II system as the leading solution for hazardous area static control. Its installation significantly improved process safety and efficiency for the customer.
Detailed Implementation in a Hazardous Environment
The HAZOP analysis of the customer's filling area, classified as a Zone 2 IIB T3 gas/vapour atmosphere, identified a specific requirement to simultaneously monitor three electrostatic protected composite hazardous area suitable Ex IBCs prior to being filled with a solvent-based resin.
Furthermore, the analysis determined that the metal funnels seated on top of these Ex IBCs were potentially isolated conductors, necessitating an independent monitoring connection. This led to the use of a total of six monitoring connections for the complete setup.
The operating environment included a non-hazardous switch room adjacent to the filling room. This switch room houses the PLC responsible for controlling the hazardous area certified pumps, which drive the flow of material from structurally earthed mixing tanks to the Ex IBCs via metal pipework.
A CompEx accredited installer strategically determined the most practical location for the installation to be the switch room. Here, the power supply unit, monitoring control unit, and marshalling junction box were positioned next to the PLC, with the latter two components terminated to a common pre-verified earth bar.
From this central point, intrinsically safe Ex ia monitoring circuits were routed via overhead cable trays to remote indicator stations, which were precisely positioned local to each filling station.
Finally, two-pole clamps and cable assemblies were specified for each of the Ex IBCs and funnels. All clamps were equipped with penetrative tungsten carbide tips, a critical feature designed to mitigate the potential for viscous product deposits to prevent a reliable ≤ 10 Ω connection from being achieved.
Key Benefits of the Earth-Rite® MULTIPOINT II Installation
- **Accessible Visual Indication**: The strategic positioning of the monitoring control unit and remote indicator stations provides easily accessible visual indication to operators both inside the potentially hazardous atmosphere and those located remotely in the switch room.
- **Minimized Interlock Control Circuit Runs**: By positioning the power supply unit local to the PLC, interlock control circuit runs were significantly minimized. The installer grouped the two channels allocated to each filling station in series and interfaced them with the PLC. The PLC was programmed to inhibit the operation of the inline transfer pump until the two channels allocated to that filling station obtained a permissive output. This 'grouping' approach prevented cross-interference between respective filling operations, highlighting the system's inherent flexibility.
- **Future-Proofing**: The inclusion of two spare channels 'future-proofs' the equipment, allowing for potential operational expansion or changes to process requirements without additional major reconfigurations.
Versatility and Further Applications
This successful implementation is just one example of the diverse hazardous area/EXLOC applications for which the Earth-Rite® MULTIPOINT II can be effectively utilized.
Should you have a potential application in mind, a Newson Gale Sales Engineer is available to discuss your specific requirements in further detail.