Loss-in-weight feeders require periodic refill from an external device such as a screw conveyor, bin activator, pneumatic conveyor, slide gate valve, or rotary valve.
A loss-in-weight feeder consists of three components: a scale with a dedicated controller to weigh material; a feed mechanism (screw, vibrating tray, etc.) with a variable-speed drive to introduce material into the process; and an integral weigh hopper for material storage.
As the name suggests weight feeder, the unit measures a loss in weight over a certain period of time and adjusts the feed mechanism output accordingly.
A typical accuracy statement for a loss-in-weight feeder specifies repeatability as a percentage of the sample-size at a given statistical confidence level.Compared to the feeding time, the refill time needs to be as short as possible to maximize the percentage of time the feeder is under gravimetric control.
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