Bag filling scales are available with a mechanical weighing mechanism or a digital weighing mechanism.
Mechanical Bagging Scales
Mechanical scales have a counterbalance weight system. Certified counterweights (i.e. 1, 2, or 5 lb.) are hung on the scale. A smaller weight on a slide bar (much like the old doctor’s scale) or a threaded rod is used for fine adjustment &/or taring the bag. Mechanical scales are activated by a pull lever.
Mechanical bagging scales:
- are less expensive
- are easy to set up
- require no electricity or compressed air
- typically used for free-flowing products such as grain, seed, fertilizers, or plastic pellets.
Digital Bagging Scales
Digital scales use load cells to measure the weight of the product. “A load cell is a transducer that creates an electrical signal whose magnitude is directly proportional to the force being measured”(1). Digital scales have a digital display and a PLC (programmable logic controller) that is used to control the scale’s operation (i.e. open/close feed gates, clamp/unclamp bags). In addition, multiple product weight parameters can be stored allowing for easily changing bag sizes. Digital scales are activated by a whisker switch or start button.
Digital bagging scales:
- are more expensive
- are more precise
- require electricity (may require compressed air depending on options)
- can store weight programs & transmit data
(1) Wikipedia. org-Load Cell