Q. Are all Airslide® fabric media's the same?

A. Many design considerations are necessary for a good quality fabric media such as materials of construction, temperature limitations, fabric media fluidization characteristics or permeability, tensile strength, etc. While each of these parameters are critical in the design of the fabric media, the most critical is the permeability of the fabric. Improper fabric permeability can cause major problems with material fluidization, consequently, material flow throughout the Airslide®. FLSmidth-Pneumatic Transport has developed a stringent specification that defines the materials & methods of construction for our Airslide® fabric media very closely. This stringent control provides our customers with a quality product that is continually monitored & reviewed accordance with specifications.

Q. What are the critical clearances that need to be considered for rotary feeders, and how best are the clearances measured?

A. Rotary feeder clearances are specified as "cold clearances" and are normally based at 70 degrees F. The "cold clearances" are also specified within a minimum and maximum tolerance. The Feeder motor should be disabled when checking clearances. There are two types of feeders to consider. The first type is a feeder with an open end rotor. Critical clearance measurement for a feeder with an open end rotor consist of both peripheral clearance and end clearance. The second type is a feeder with a closed end or shrouded rotor. Critical clearances for a feeder with a closed or shrouded rotor consist of total peripheral clearance only. Typically, end clearances for closed end or shrouded rotors are large (3/8" or larger) and are not considered critical machined clearances. Therefore, it is not necessary to measure end clearances on feeders having closed end or shrouded rotors. Peripheral clearances are normally measured using a feeler gauge. It is best to measure these clearances at three locations along the feeder blade at the feeder inlet port. and then at the 180 degree opposite blade at the feeder discharge port. Feeler gauge measurements between the blade and the feeder body should be taken and recorded at each side and in the middle of each blade. Total peripheral clearance is determined by adding the measurements taken at the inlet port and the 180 degree opposite discharge ports and seeing if they fall within the tolerances specified. It is recommended that total peripheral clearance be checked for at least every other set of blades in a rotary feeder. End clearances apply to feeders with open end rotors only and are also measured using a feeler gauge. End clearances are measured between the edge of the open end rotor and feeder headplates on each side of the feeder. Total end clearance is determined by adding the clearances measured at each end of a given blade, and then comparing those values to the specified tolerances. It is recommended that total end clearance be checked for at least every other set of blades in a rotary feeder.