Recent legislation brought about by combustible dust explosion tragedies has sounded an alarm for many manufacturers. Hearing the message, a confectionary products manufacturer, located near Pittsburgh, Pennsylvania, undertook a $2 million dollar plant upgrade to proactively address combustible dust safety issues. Making candy requires a large amount of sugar and starch (which are highly combustible) to be conveyed and introduced along the production process resulting in a number of potential dust issues.
Initially, the company contracted a process safety services company to perform a plant hazard analysis. Those findings were then given to a consulting engineer to develop a detailed plan for explosion protection. The plan included venting, isolation, suppression and structural reinforcement to meet the Kst value for starch and sugar. The explosion severity testing results indicated Pmax 7.5 to 8.5 bar and Kst 119-163.
Chemical Suppression Systems
IEP Technologies, formerly Fenwal Protection Systems of Ashland, MA (represented by SysTech Design Inc.) was selected to engineer and supply the necessary explosion protection equipment.
The explosion suppression systems, as supplied by IEP, were comprised of dynamic pressure sensors, charged piston fired suppression bottles and monitoring controls. Existing Fenwal hardware was reconfigured.
Three (3) existing dust collectors were retrofitted with sodium bicarbonate suppression systems retrofitted to them, with one (1) collector requiring a passive isolation valve. In addition, six (6) existing receivers and four (4) starch bins were structurally reinforced and fitted with chemical suppression and isolation bottles. The isolation bottles installed were PistonFire II Suppressors and HRD Spherical Dry Chemical Extinguishers.
Handling potentially explosive dusts requires a vigilant/proactive approach; hats off to the owner of this company for recognizing the need to upgrade to a safer facility.