Minimum Order Quantity (MOQ): 1 pallet (typically 125–250+ bulk bags)
To specify a duffle bottom on an FIBC purchase order, do not simply write “duffle bottom.” Clearly identify the required wide-opening bottom discharge construction, closure method, opening geometry, liner configuration if applicable, product characteristics, required discharge behavior, receiving equipment, body construction, top style, Safe Working Load, safety factor, fabric, lift loops, dimensions, critical tolerances, printing, packing, and approved specification revision.
Here is a bad purchase order:
“White bulk bag with duffle bottom.”
Sounds specific.
It isn’t.
How much of the bottom opens?
How is it closed?
How does the operator release it?
What product is inside?
Is the material bulky?
Does it bridge?
How quickly should the bag empty?
Can the receiving hopper handle that flow?
Is there a liner?
What happens to the liner when the outer bottom opens?
What is the SWL?
What is the safety factor?
What body construction is required?
If those answers exist only inside somebody’s head, you do not have a controlled FIBC specification.
You have a gamble.
A duffle bottom generally refers to a wide-opening lower discharge configuration designed to allow a large portion of the bottom to open during unloading.
The bottom remains securely closed while the FIBC is:
Filled.
Handled.
Palletized.
Stored.
Transported.
Moved to the unloading station.
At the discharge point, the closure is released according to the intended process.
The wide lower opening allows product to evacuate.
Use terminology that describes the function clearly.
For example:
Bottom Construction: Duffle Bottom / Wide-Opening Discharge With Approved Closure
Then reference the controlled drawing or specification that defines the exact construction.
That is much stronger than:
Bottom: Duffle
Because the phrase only tells you one thing:
The bottom is intended to open broadly.
It does not tell you:
How broadly.
How it closes.
How it interfaces with the liner.
How operators access it.
What material is inside.
How fast product should discharge.
What equipment receives it.
How much the FIBC carries.
How the bag is filled.
How the bag is lifted.
How the bag is stored.
Those details determine whether the design actually works.
At minimum, control these areas:
| Specification | What to Define |
|---|---|
| 🔻 Bottom | Duffle bottom / wide-opening discharge |
| 📐 Opening | Required bottom-opening geometry |
| 🔒 Closure | Required closure configuration |
| 👷 Access | Intended operator access/release method |
| 📦 Product | Material being packaged |
| ⚗️ Bulk density | Actual or approved range |
| 🌊 Flowability | Product discharge behavior |
| ⚡ Discharge | Required unloading behavior |
| ⚙️ Equipment | Receiving system |
| 🔵 Top | Open, duffle, filling spout, etc. |
| 🏗️ Body | Circular, U-panel, four-panel, baffle, etc. |
| ⚖️ SWL | Required Safe Working Load |
| 🛡️ Safety factor | Required classification |
| 🧵 Fabric | Required FIBC fabric |
| 💧 Coating | Coated or uncoated |
| 🛍️ Liner | Required liner configuration |
| 🪢 Lift loops | Style and critical dimensions |
| 📐 Dimensions | Required FIBC dimensions |
| 📏 Tolerances | Critical dimensional tolerances |
| 🪵 Pallet | Filled-footprint requirements |
| 🏭 Storage | Warehouse requirements |
| 🚚 Logistics | Nationwide transportation requirements |
| 🏷️ Printing | Identification and markings |
| 📄 Revision | Approved specification revision |
The PO line itself can remain concise.
The referenced technical specification should not.
Do not leave the intended function ambiguous.
A good specification clearly communicates that the bottom is designed for broad product discharge.
For example:
Bottom Construction: Duffle Bottom / Wide-Opening Discharge With Closure
Then define the actual geometry through the approved drawing.
This is important because terminology can vary.
One supplier’s interpretation of a “duffle bottom” may not perfectly match another supplier’s.
If the opening geometry is critical, use:
A controlled drawing.
Approved construction detail.
Reference sample.
Defined dimensions.
Do not rely exclusively on terminology.
What is the operational objective?
Maximum product evacuation?
Reduced bridging?
Rapid discharge?
Accommodation of bulky pieces?
The required opening should be designed around the material and process.
Do not automatically choose the largest possible opening.
The closure has a serious job.
It needs to keep the bottom secured during:
Filling.
Handling.
Storage.
Nationwide transportation.
Pallet movement.
Forklift handling.
Receiving.
Only at the intended discharge point should it be released.
Specify the closure configuration.
This gets ignored until the bags reach the plant.
Then somebody asks:
“How are we supposed to open this?”
Do not wait until then.
Determine:
Where the operator stands.
How the bottom is accessed.
What unloading equipment surrounds the bag.
What clearances exist.
How the closure is released.
Document critical requirements.
Tell the supplier what the bag is supposed to do.
For example:
Intended Discharge: Rapid full-bag discharge into approved receiving hopper.
That one sentence provides valuable context.
It explains why the wide-opening bottom exists.
Duffle bottoms are often strongest when the entire FIBC empties in one discharge cycle.
If that is the process, say so.
Do not leave the supplier guessing whether you expect partial discharge.
If partial discharge is necessary, this deserves special attention.
A wide-opening bottom is generally less naturally suited to controlled stop-and-start feeding than a conventional discharge spout.
If partial discharge matters, define it before approving the design.
If production needs carefully regulated flow, communicate that.
A duffle bottom may not be the best configuration.
Do not specify a wide opening and later complain that it releases too much product.
Call or Text us at 832.400.1394
If unloading time matters, define the operational requirement.
You may not need an exact theoretical flow rate.
But purchasing should know whether the objective is:
Rapid full discharge.
Moderate discharge.
Controlled feeding.
A specific production cycle.
That information affects the design decision.
What receives the product?
A hopper?
Bin?
Conveyor?
Mixer?
Processing vessel?
Collection area?
Other bulk-material system?
The FIBC and receiving equipment need to work together.
A wide-opening bottom can release product quickly.
Can the equipment underneath handle it?
That is the question.
Do not optimize the bag to dump faster than the plant can process.
Physical geometry matters.
How large is the hopper?
Where does the product stream need to land?
How much room exists around the bottom?
Can the duffle section fully open?
Measure the actual station.
State the product.
Do not write only:
Dry bulk material.
Identify the actual material or controlled product family.
Different products behave completely differently during wide-opening discharge.
Bulky materials are one of the major reasons to consider duffle bottom.
If the product contains larger pieces, communicate that.
It helps explain why a conventional discharge spout may be too restrictive.
Irregular pieces can:
Catch.
Interlock.
Bridge.
Jam.
That information matters when selecting the bottom.
If particle dimensions affect discharge, document the relevant range.
This can be particularly important when the duffle bottom is being selected to avoid restricted-outlet jamming.
Does the product:
Flow freely?
Bridge?
Compact?
Clump?
Interlock?
Hang up?
Become cohesive?
Flowability should be discussed before the bottom is locked.
If the existing process has bridging problems, say so.
Do not simply request a duffle bottom without explaining why.
The problem itself is valuable specification information.
Same idea.
If conventional outlets jam because of product geometry, document it.
That gives engineering and suppliers the information needed to evaluate the wide-opening design.
Bulk density affects:
Required bag volume.
Target payload.
Discharge behavior.
Product impact.
Receiving-equipment load.
Know it.
State how much product should be loaded into each FIBC.
Do not simply fill until the bag appears full.
Payload needs to remain within the approved Safe Working Load.
Use an actual SWL requirement.
Not:
Heavy duty.
Extra strong.
Industrial.
Those phrases are not technical load ratings.
Document the appropriate safety factor or intended-use requirement.
Remember:
Safety factor does not increase the approved working payload.
Never use it as permission to overload the FIBC.
Duffle bottom tells you nothing about filling.
You still need to define the top.
Common combinations may include:
Open Top / Duffle Bottom
Duffle Top / Duffle Bottom
Filling Spout Top / Duffle Bottom
Treat top and bottom as separate decisions.
A specification might state:
Top Construction: Full Open Top
Bottom Construction: Duffle Bottom / Wide-Opening Discharge With Closure
This provides broad access at both ends.
A duffle top provides broad filling access with the ability to close the upper section.
The bottom then provides broad discharge.
Specify each independently.
This can make sense when filling equipment requires a defined inlet but unloading requires broad discharge.
A PO may state:
Top Construction: Filling Spout With Approved Closure
Bottom Construction: Duffle Bottom / Wide-Opening Discharge With Approved Closure
Then define both systems.
Duffle bottom does not define body style.
Specify whether the FIBC uses:
Circular.
U-panel.
Four-panel.
Baffle.
Or another approved construction.
For example:
Body Construction: Circular
Bottom Construction: Duffle Bottom / Wide-Opening Discharge
Now there is no confusion between body and bottom.
Same rule:
Body Construction: U-Panel
Bottom Construction: Duffle Bottom / Wide-Opening Discharge
If four-panel construction is required, write it.
Do not rely on an old photograph or supplier assumption.
If filled shape and warehouse cube efficiency matter, baffles may be useful.
Specify them separately from the bottom.
Coating and bottom style solve different problems.
Coated fabric may improve fine-particle containment and resistance to moisture moving through the woven structure.
Uncoated fabric provides more breathability.
Choose based on the product.
This is where wide-opening bottoms can get interesting.
The outer FIBC opens.
What does the liner do?
If the answer is:
“We don’t know.”
The specification is incomplete.
If a liner is required, define its construction.
Loose liners can be economical.
But they can move.
Form-fit liners provide more controlled geometry.
But they may add cost.
Choose based on actual requirements.
This may be the single most important liner question.
When the outer duffle bottom opens, how does product leave the liner?
Does the liner have its own opening?
How is it released?
How does it align?
Can it collapse into the product stream?
Define the system.
A liner that moves excessively during filling or discharge may create problems.
If positioning matters, specify the approved attachment or positioning requirements.
If the liner needs its own closure, document it.
Do not assume the outer duffle closure handles the liner automatically.
If moisture can damage the product, define the actual requirement.
Consider:
Fabric.
Coating.
Liner.
Top closure.
Bottom closure.
Seams.
Storage.
Transportation.
Do not simply write:
Waterproof bag.
Define the exposure and performance needed.
A wide-opening bottom can release a substantial amount of product and displaced air.
If the material is dusty, communicate it.
Dust requirements may influence:
Receiving equipment.
Containment.
Liner.
Fabric.
Discharge procedure.
If cleanliness matters, define it.
The FIBC may need specific:
Fabric.
Liner.
Manufacturing.
Handling.
Storage.
Closure.
Discharge requirements.
Bottom style alone does not address contamination.
If the product or environment creates electrostatic concerns, communicate the application.
Do not assume the bottom construction determines electrostatic classification.
Abrasive products can place demanding conditions on the FIBC.
Especially during rapid discharge.
Communicate abrasion.
Sharp or angular materials may increase puncture or wear risk.
A large discharge opening can reduce jamming.
It does not eliminate fabric-damage concerns.
If the material enters the FIBC at elevated temperature, document it.
Do not assume a standard woven polypropylene configuration is appropriate for unusual product temperatures.
The FIBC needs to be lifted and positioned over the receiving system.
Loop configuration affects:
Handling.
Discharge positioning.
Equipment compatibility.
Operator access.
Specify it.
Call or Text us at 832.400.1394
Loop length affects overall hanging geometry.
If the bag hangs too low, the bottom may interfere with the receiving equipment.
If it hangs differently than expected, operator access may change.
Control critical dimensions.
Calculate the entire system:
Lift loops.
FIBC body.
Duffle-bottom section.
Receiving equipment.
Required clearance.
Do not design the bag and unloading station independently.
Define dimensions using a consistent convention.
Remember:
An empty flexible bag and a filled flexible bag are not geometrically identical.
If filled footprint matters, test it.
Control dimensions that actually affect the process.
Potential examples include:
Loop length.
Overall bag height.
Top opening.
Filling-spout dimensions.
Critical body dimensions.
Bottom-opening geometry.
Equipment-interface dimensions.
Do not tighten every dimension unnecessarily.
If pallet and warehouse efficiency matter, define the acceptable filled footprint.
Body construction and product behavior affect this more than the bottom style.
Document:
Required pallet compatibility.
Acceptable overhang.
Handling method.
Filled stability.
Bottom-positioning requirements.
The duffle closure needs to remain properly contained while the FIBC sits on the pallet.
Consider:
Storage duration.
Filled shape.
Stacking or racking practices.
Handling frequency.
Moisture.
Temperature.
Product protection.
Closure integrity.
The bag may spend weeks or months in storage before the bottom is ever opened.
The duffle closure must remain secure through the entire logistics chain.
That may include:
Forklift handling.
Loading.
Vibration.
Long-distance transportation.
Unloading.
Warehouse transfers.
Repeated movement.
Design for the journey.
If outdoor storage is expected, communicate it.
Consider:
UV.
Rain.
Humidity.
Temperature.
Storage duration.
Ground conditions.
Liner.
Fabric.
Closures.
Duffle bottom does not automatically mean weatherproof.
Document required:
Product identification.
Warnings.
Handling instructions.
Company information.
Lot information.
Traceability.
Other required markings.
Use controlled artwork when appropriate.
How should the empty bags arrive?
Folded?
Baled?
Palletized?
Liners pre-installed?
Bottoms pre-closed?
If the receiving process depends on the packing configuration, specify it.
Give the approved design an identity.
For example:
FIBC Item DB-210 — Rev. B
Now purchasing can order an exact controlled configuration.
Much better than:
“Those duffle-bottom bags we bought last year.”
Maybe operations changes the bottom opening.
Maybe engineering changes loop length.
Maybe the liner changes.
Maybe the top changes.
Maybe the receiving equipment changes.
Update the revision.
Do not let multiple configurations circulate under one item description.
This phrase causes problems.
Which shipment?
Which revision?
Which supplier?
Were there undocumented changes?
Reference the controlled item number and current revision.
Operations says:
“Make the bottom open wider next time.”
Supplier agrees.
New bags arrive.
They work beautifully.
Nobody updates the drawing.
Six months later the old design gets ordered.
Problem returns.
Document the change.
A photo can show general construction.
It cannot reliably communicate:
SWL.
Safety factor.
Bottom-opening geometry.
Closure.
Fabric.
Liner.
Critical tolerances.
Product requirements.
Use specifications.
A useful PO description could follow this structure:
FIBC — [Top Construction] / [Body Construction] / Duffle Bottom Wide-Opening Discharge With Approved Closure / [Required SWL] / [Required Safety Factor] / [Lift Loop Configuration] / [Coated or Uncoated] / [Liner Requirement] / Per Approved Specification [Revision]
Then reference the controlled drawing containing the exact construction details.
A controlled specification might include:
Top: Approved top construction
Body: Approved FIBC body construction
Bottom: Duffle Bottom / Wide-Opening Discharge
Bottom Opening: Per approved drawing
Bottom Closure: Approved configuration
Intended Discharge: Rapid full-bag discharge or approved process
Receiving Equipment: Approved equipment/interface
Product: Approved bulk material
Bulk Density: Approved value or range
Target Payload: Approved fill weight
SWL: Required Safe Working Load
Safety Factor: Required intended-use classification
Fabric: Woven polypropylene per specification
Coating: Coated or uncoated as required
Liner: Approved configuration if required
Liner Discharge: Per approved design
Lift Loops: Approved style and dimensions
FIBC Dimensions: Per drawing
Critical Tolerances: Per specification
Pallet: Approved configuration
Printing: Per controlled artwork
Packing: Per approved requirement
Revision: Current approved revision
Now you have something purchasing can actually control.
For broad access at both ends:
Top Construction: Full Open Top
Bottom Construction: Duffle Bottom / Wide-Opening Discharge With Approved Closure
Then reference the complete approved specification.
For broad filling plus top closure:
Top Construction: Duffle Top With Approved Closure
Bottom Construction: Duffle Bottom / Wide-Opening Discharge With Approved Closure
Define the top and bottom independently.
For controlled filling and broad discharge:
Top Construction: Filling Spout With Approved Closure
Bottom Construction: Duffle Bottom / Wide-Opening Discharge With Approved Closure
Then define:
Filling-spout dimensions.
Bottom-opening geometry.
Closures.
Liner.
Equipment interfaces.
Before releasing the PO, confirm:
If you cannot answer numbers thirteen through seventeen, you probably are not ready to finalize the bottom.
Common mistakes include:
Writing only “duffle bottom.”
Assuming every supplier uses the term identically.
Never defining the opening geometry.
Choosing the largest opening possible.
Ignoring closure design.
Ignoring operator access.
Ignoring receiving equipment.
Ignoring equipment capacity.
Ignoring discharge rate.
Ignoring bulk density.
Ignoring product impact.
Ignoring partial discharge.
Ignoring metering requirements.
Ignoring product flowability.
Assuming a large opening fixes every bridging problem.
Ignoring liners.
Ignoring liner discharge.
Ignoring lift-loop length.
Ignoring overall hanging height.
Ignoring filled footprint.
Ignoring nationwide transportation.
Ordering from a photograph.
Using “same as last time.”
And failing to control revisions.
Ask:
Does the current product bridge?
Does it jam conventional outlets?
How long does unloading take?
Do operators intervene?
Does the entire FIBC empty at once?
Is partial discharge required?
Is flow too fast or too slow?
How much residual product remains?
Does the liner cause problems?
How much cleanup is required?
Operations can tell you what actually happens.
Ask:
What receiving equipment is used?
How much product can it accept?
What vertical clearance exists?
What bottom-opening geometry works?
What loop dimensions matter?
What operator-access requirements exist?
Which tolerances are actually critical?
What happens if the product releases rapidly?
Those answers belong in the controlled specification.
Ask:
Does the filled FIBC fit the pallet?
Does it bulge excessively?
Does the bottom remain secure?
Are the loops accessible?
Does the closure create handling problems?
Does the bag remain stable?
Do storage conditions affect the product?
Warehouse performance matters too.
An empty sample proves very little about discharge.
Fill it.
Use the real product.
Use the intended payload.
Move it.
Store it.
Palletize it.
Position it over the actual receiving system.
Then open the bottom.
Watch.
Does product evacuate cleanly?
Does it bridge?
Does it surge?
Does it overwhelm the hopper?
Does the liner interfere?
Does dust increase?
Does product spill?
How much remains?
That is a real test.
Approve the system.
Not the appearance.
Verify:
Filling.
Target payload.
Filled shape.
Handling.
Pallet fit.
Closure security.
Storage.
Liner behavior.
Lift-loop compatibility.
Hanging height.
Operator access.
Receiving-equipment compatibility.
Discharge rate.
Product evacuation.
Dust.
Spillage.
Residual product.
Only then lock the specification.
Detailed enough that nobody needs to guess about anything that can materially affect performance.
The PO description can be short.
The referenced drawing and specification should carry the technical detail.
That is the cleanest way to purchase custom FIBCs repeatedly.
A controlled specification can improve:
Quote comparison.
Purchasing.
Receiving.
Quality control.
Operator training.
Inventory management.
Discharge consistency.
Supplier communication.
Repeat orders.
Troubleshooting.
The entire organization works from one approved design.
Compare equivalent bags.
Same product.
Same payload.
Same SWL.
Same safety factor.
Same top.
Same body.
Same bottom-opening geometry.
Same closure.
Same fabric.
Same coating.
Same liner.
Same liner discharge.
Same loops.
Same dimensions.
Same printing.
Same packing.
Then compare price.
If those things differ, you are not comparing the same FIBC.
Start with the function:
Bottom Construction: Duffle Bottom / Wide-Opening Discharge With Approved Closure
Then work backward from the unloading process.
What product is inside?
Is it bulky?
Irregular?
Free flowing?
Cohesive?
Does it bridge?
Does it jam conventional outlets?
What is the bulk density?
What is the target payload?
Does the entire FIBC empty at once?
How quickly should it empty?
Does production require metering?
Does production require partial discharge?
What equipment receives the product?
Can that equipment handle the flow?
How large does the bottom actually need to open?
How is the closure accessed?
What does the liner do when the bottom opens?
Then specify the rest.
Top.
Body.
SWL.
Safety factor.
Fabric.
Coating.
Liner.
Lift loops.
Dimensions.
Critical tolerances.
Pallet requirements.
Warehouse requirements.
Nationwide transportation.
Printing.
Packing.
Revision.
And then do the part that matters most.
Test it.
Fill the actual FIBC with the actual product.
Take it to the intended payload.
Handle it.
Store it.
Move it.
Put it over the actual receiving system.
Release the actual bottom.
Watch the actual product.
If the material evacuates cleanly, the receiving equipment keeps up, the liner behaves, the closure works, operators can access it, residual product is acceptable, and the process is faster and cleaner than the alternative—
you have a specification.
Until then, you have a theory.
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