Best practice (and in many cases a legal requirement) to prevent wasteful, dangerous and environmentally harmful product spills when filling tanks, vats, road tankers or other containers is that a hard wired safety system be installed to stop the filling before the safe level is exceeded.
We can provide high-level alarm systems that signal the approach of a dangerously high level in a storage tank, and take appropriate action through the control system to stop the filling operation.
This alarm can be from a level probe, or if the vessel is fitted with a level gauge, can be a high level switch in the gauge, or derived from the gauge level output.
The hard wired overspill protection is achieved by connecting the output from a separate level sensor to a safety relay system that automatically closes down any potential supply into the vessel.
The level of safety required is determined by carrying out a review of the process to obtain the safety integrity level (SIL) required. The protection system should then be designed to satify the SIL level determined by the safety review.
For information on SIL see http://www.iceweb.com.au/sis/target_sis.htm