How are Closed Loop Fumigation (CLF) systems installed in grain storages?
Because sealing was normally better at the base of storage units than in the roof and headspace area, CLF systems were designed to pull gas from the headspace and push gas into the base area. Although 6 inch PVC pipe was used initially on some large steel bins for the suction pipe, later designs standardized on 4-inch ID Schedule 40 PVC pipe as the suction and pressure plumbing. Initially the suction point was mid-roof or near the peak, but later steel bin and flat storage designs placed the suction pipe entry point through the vertical sidewall just below the roof eave junction. Two 90 degree elbows were used to sandwich the bin sidewall material, providing a turndown inside the bin to keep grain out of the pipe. Flexible tubing was used to connect the CLF blower inlet and outlet to the bin, making the assembly of the CLF system less critical. On steel bins and flat storage warehouses, the pressure piping was connected to all aeration fan transitions or ducts. On steel bins and concre
