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Gravity Conveyor - Storage Solutions, Inc.

Demystifying Conveyor System Lingo…

Conveyor industry speak can be incredibly confusing for conveyor system shoppers, and if you don’t have a special dictionary to guide you in your decision making, it’s hard to figure out all of the terminologies. One of the prime examples of this specialized language is the term “BF” which refers to “between- frame”, a term used to size gravity conveyor systems including pallet flow, tote flow, gravity roller, and carton flow conveyors. While you may not understand the importance of BF immediately, it becomes clearer once we get past all the jargon and explain the purpose and importance of this calculation.

When buying gravity roller conveyors or replacement rollers only, the between-frame measurement is what is needed to accurately recommend a solution. The length of a conveyor system roller is normally described by its between-frame measurement, which is the dimension between the frame or between the rails of the conveyor. Overall width can vary depending on the frame size generally adding 3” or more to the overall width.

Defining BF for Your Conveyor System

Gravity Conveyor Systems - Storage Solutions Inc.

Generally speaking, the BF should be about 2 inches wider than the widest package on your shelf. Other factors to consider when calculating your between-frame measurements include your type of conveyor system and the positioning of the wheels. If the wheels or rollers are positioned on the top of the conveyor, the package width may exceed that of the frame, providing it is stable and not in danger of contact with other packages on the conveyor. If the conveyor has a curved area, the frame width will need to be wider to give packages room to turn as they move down the system.

Conveyor System Design Considerations & Options:

  • Typical roller size is 1.9” in diameter with options for 2.5”, 2-⅝”, 3-½” diameter and larger.  Multiple gauges are available.
  • Rollers and frames are available in galvanized steel to prevent rust and tarnishing to keep a new looking appearance. 
  • Bolt-on or welded guide rails added to the top of the frame to separate totes, boxes, and containers that are being conveyed
  • Bolt-on or welded end stops that terminate the flow at the end of the conveyor. 
  • Multi-Poly Tier supports allow for two or more levels of conveyor to be stacked and used simultaneously
  • Supports are available in adjustable and fixed heights painted and galvanized. Adjustable supports can be sized per application.
  • Ceiling hangers are available for utilizing valuable floor space when higher conveyor elevations are required. Typical support is a cross-pipe mounted to the underside of the bed section supported by threaded galvanized rods.


If you need help calculating your between-frame measurement for your conveyor system, SSI is ready to help you make sense of it all. We’ve spent years helping companies just like yours implement customized conveyor solutions beginning with your BF calculation. Contact a member of our team at 865-540-4004 to discuss your needs and what we can do for you. We proudly serve customers in Tennessee, Alabama, and throughout the Southeast.