- by Elay Plastic
- 02 August 2026
How to Match FIBC Inlets and Outlets to Your Equipment
A practical explanation of top and bottom constructions—and the process information needed to specify them correctly.
The bag must connect to the process
FIBC inlet and outlet designs should be selected around the customer’s filling and emptying equipment. The diameter and length of a spout, the available headroom, the product flow rate and the required dust control can be more important than the generic name of the closure.
Before selecting a top or bottom, map the complete movement from the filling station through storage and transport to final discharge.
Open top and skirt top
A full open top provides wide access and can suit coarse or freely flowing products where containment during filling is not the main concern. It may be closed with a cover, flap or other agreed construction after filling.
A skirt top offers a wide inlet with additional fabric that can be gathered and tied. It can provide more closure flexibility while retaining broad access.
Filling spouts
A filling spout is designed to connect with a chute or filling head. Spout diameter and length must suit the equipment and product flow. A tie, draw cord or flap can support closure after filling.
Fine or aerated powders may need attention to dust extraction and air evacuation. Excessive filling pressure should not be treated as a bag problem alone; the complete filling system needs review.
Flat bottoms and discharge spouts
A flat or closed bottom is appropriate when the bag will be emptied by cutting, tipping or another controlled process. A discharge spout allows reusable connection to downstream equipment and can support more controlled flow.
Outlet diameter, length, closure, protective flap and product flow behaviour should be specified together. Products that bridge, cake or flood may require special consideration beyond a standard spout.
Protecting operators and product
The filling and discharge arrangement influences dust exposure, contamination risk, manual intervention and uncontrolled release. Buyers should describe how operators connect, untie and control the outlet and whether the process is enclosed.
Never stand beneath a suspended FIBC or allow personnel to enter an unsupported discharge area. Follow the approved handling procedure and the supplier’s instructions.
Dimensions needed for a reliable specification
Provide filling-head and discharge-station dimensions, connection diameters, available clearance, filling rate, required closure, discharge rate and whether the bag must be resealable. Include liner connections if a liner is required.
A dimensional drawing or completed specification form reduces misunderstandings and gives both parties a clear basis for approval.
Relevant standards and guidance
- The approved supplier specification and handling label for the selected filling and discharge design
- ISO 21898:2024 — selection and safe use of FIBCs for non-dangerous goods
Important: Final suitability depends on the packed product, process, handling environment and approved technical specification. Consult the responsible safety or dangerous-goods specialist where applicable.