Lecture 17 Flat Structures

Aeration for Flat Structures Ideally - uniform air flow – "dead zones" –min. of.2 cfm design rate (this is double) –fines concentrate under filling auger... –Duct pacing and storage – less than or equal to grain depth – longest air path should be less than or equal to 1.5 times the shortest path – max. slope to grain = 10%

Aeration for Flat Structures Duct Sizing – number of bushels – airflow rate – design velocity Positive vs Negative pressure –2,500 fpm = positive – 1,500 fpm = negative

Grain Sampling and Inspection Tell Tale signs – leaking grain – bulging walls – snow melting off the roof Prevention of dead zones... – perforated flooring best – when ducts are used: probe "dead zones

Preventing spoilage – perforated floor best, but fines accumulate below the floor - good spot for insects –checking "dead zones" –ducts can have fines accumulate, however cleaning and treating is much easier. –"core" in center of bin (where grain unloads) prevents air movement- spreader –probe areas where the probing is more difficult –filling and unloading leads to stagnant grain –Stirring devices –use of a vapor barrier –sealing bottom ring to concrete

Sampling equipment needed Moisture tester Sampling probe Temperature probe Measuring tape Grain dividers Scale to weigh foreign material

Getting a good sample Divide bin into 5 equal parts use probe Sample each section

Still concerned? Fan test... Musty odor? Corrective Action – Insects - fumigate – Wet - dry – Hot - aerate Note- Value of sampler greater than value of sample