Safety in the Plant
in hazardous levels of charge to be accumulated on the process, presenting a very real risk of static ignition. Employing a system with the ability to interlock with the process and can execute an automatic shutdown of the process equipment if a compromised ground connection is detected can mitigate this, until operators return to resolve the earthing connection issue.
The Earth-Rite range has interlocking capability, reducing operator dependency to have constant clear line of sight to identify when the system has gone non-permissive (LED has gone red) and perform a manual shutdown. The ground loop monitoring system ensures a positive connection resistance of 10 ohms or less, as displayed on the monitoring unit via a pulsing green LED.
drum can, on occasion, be thick enough as to avoid electrostatic charge dispersion. You must have metal-to-metal contact between the clamp tips and the surface of the vessel to be able to achieve a low resistance to earth.
To reliably penetrate built up layers of material like rust or paint, Tungsten Carbide teeth tips are powerful enough to continuously bite through coatings, rust or product deposits that a basic alligator clip or welding clamp would struggle with. Ultimately, although a clamp and cable is a suitable initial layer of protection in mitigating the risk of an electrostatic discharge, it is based on the assumption that there is a path to earth. The optimum solution is to provide
operators with a visual means of verifying a connection to equipment at risk of static charge accumulation with a resistance of 10 Ohms or less, as stated by the IEC 60079-32-1 “metallic items in good contact with earth should have a resistance to it of less than 10 Ohms”.
Visual indication and continuous ground circuit monitoring are two fundamental layers of protection that go hand in hand. Whilst Newson Gale’s Cen-Stat range of ATEX/FM approved clamps and cables provide continuity to earth, pulsing green ground status indicators provide operators with a verified visual reference point to ensure that equipment they are operating is grounded prior to, and during, the process. Monitoring proves a connection on repeated use, verifies the integrity of the grounding cable and the green light indicator enables operators to take responsibility for ensuring the equipment does not pose a static ignition risk.
“Newson Gale systems do not use arbitrary values of resistance. When our ground status indicators go green, your operators are working in compliance with NFPA, IEC, API and CENELEC industry codes of practice.”
Whilst the Bond-Rite range of systems provides visual indication of when grounding is present or lost, and continuous monitoring of the equipment’s ground resistance, it is still very much operator-dependent and susceptible to human error.
In a drum mixing application, operators may not be present throughout the duration of the process, the loss of grounding when unattended may result
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Despite the ever-present dangers, the primary mind set should be to source a grounding solution that best fits your objectives. The more layers deployed to protect against an ignition source, the more likely static will be controlled in a safe, repeatable and reliable way.
To help control these risks, Newson Gale offers a wide range of static grounding and bonding equipment which is made to provide optimum safety in explosive atmospheres and other hazardous environments.
For more information please contact:
james.grimshaw@
hoerbiger.com
www.newson-gale.co.uk
ENQUIRY NO. 32
INDUSTRIAL PROCESS REVIEW
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