How to avoid the real cost of non-compliance in Static Control
The overall cost of non-compliance can stretch far beyond potential “savings” achieved by ignoring the risk of electrostatic ignitions or by using non-compliant static control methods.
More often than not, static caused fires and explosions result in expensive production downtime, legal and insurance costs related to personnel injuries & fatalities and damage to company property. In numerous cases static caused fires have led to the pollution of the local environment resulting in the loss of public goodwill and the payment of heavy fines imposed by local government. Under ATEX, the European Union’s legislation which governs the safety of personnel working in hazardous atmospheres, everybody from suppliers to company directors are open to criminal prosecution if a court determines that adequate Best Practice procedures and equipment have not been used to protect workers.
Fortunately, there are three industry produced Best Practice standards that provide the background to the nature of static electricity, the processes that are susceptible to electrostatic ignitions and the preventative measures that should be put in place to eliminate static electricity as a health and safety risk.
The best practice standards are:
- Cenelec CLC/TR:60079-32-1 (2015): Explosive atmospheres – Part 32-1: Electrostatic Hazards – Guidance.
- NFPA 77 (2014): Recommended Practice on Static Electricity,(National Fire Protection Association).
- API RP 2003 Eight Edition (2015): Protection Against Ignitions Arising out of Static, Lightning, and Stray Currents, (2003), (American Petroleum Institute).
The standards are produced by committees made up of industry experts in hazardous process safety and show remarkable consistency in the precautionary measures identified for controlling the generation of static electricity.
For example, in tank truck* transfers both CLC/TR: 60079-32-1 and API standards (NFPA references API for tank truck transfers) recommend:
1. The use of interlocks to stop flow of product preventing the generation of static if the truck loses its earth connection.
2. Monitoring the bonding/earthing circuit to less than 10 ohms and providing positive indication to operators that a positive bond/ground connection is established.
3. State the first operation in road tanker transfers is to apply a full earth connection to the vehicle.
The API standard goes a step further stating the earthing clamp should not be removed until the tank truck body is sealed, i.e. removal of the earthing clamp should be the final operation in the product transfer process.
As recommended in each of the standards the most effective method of eliminating spark gaps is to ensure all conductive and semi-conductive objects are bonded and grounded with fit for purpose static control equipment. The static control equipment should be capable of making low electrical resistance contact with charged equipment, combined with maintaining secure and reliable low resistance static dissipative circuits.
A good margin of safety can be assured by ensuring that static dissipative circuits and their connections are regularly checked for resistances greater than 10 ohms. The NFPA 77 and API standards state electrical resistances higher than 10 ohms in metal circuits are indicative of a break in the continuity of the circuit, resulting in the potential and undesirable accumulation of static electricity.