How to Properly Measure and Size a Multi-Wall Pasted Valve Bag

A Pasted Valve Stepped End (“PVSE”) multi-wall paper bag, is a common industrial packaging style designed to package a wide variety of dry flowable products. Valve bags are packed on equipment that deposits material into the bag via horizontal filling spout. When the bag is discharged from the packing equipment, forces generated by the product inside the bag allow the valve opening to self-seal.

Measuring a Valve Bag

Bag Size: 

A: Face Width is always listed first. 

B: Finished Length is always listed second.

C: Top Width is always listed third. If the Top Width and Bottom Width are the same, this will be the last dimension in the specification.

D: Bottom Width may be listed fourth. This is less common. 

Valve Size: 

Valve size will be equal to or less than the Top or Bottom Width. If the valve size is less than the Top or Bottom Width, the valve is considered to be “Reduced”.

Sizing a Valve Bag

Step 1:

Establish desired product weight to be packaged in pounds or kilograms

Step 2:

Determine bulk density of product. If loose and packed densities are known, the bag should be sized for the loose bulk density. 

Step 3:

Divide desired product weight by bulk density to determine bag volume required. 

For example: Customer desires 50lbs of material to be packed in the bag and the bulk density of the material is 35lbs/cubic foot.

Bag Volume = 50/35 = 1.43 cubic feet

Step 4:

Based on the desired volume, identify appropriate bag size “starting” point (see chart). If the required volume lies between two figures, select the larger number. 

Step 5:

Convert bag size based on desired/required dimensions 

Size Conversion Formula:

• 1 inch of bag width = 2 inches bag length
• 1 inch of bag top width (thickness) = 2 inches bag length
• 1Width: 2Length: 1Thickness

Examples:

• 18” x 23” x 5” can convert to 17” x 25” x 5” (reduce width, increase length)
• 18” x 23” x 5” can convert to 19” x 23” x 4” (increase width, reduce thickness)
• 20” x 24” x 6” can convert to 18” x 26” x 7” (reduce width, increase length, increase thickness)

Step 6:

ALWAYS VERIFY ESTIMATED BAG SIZE BY FILLING SAMPLE BAGS

Need help measuring and sizing your multi-wall paper bags? 

Contact our experienced team for all your technical bag questions. Whether you need an in-stock bag for immediate shipment or a custom designed solution, Southern Packaging is here to assist. Give us a call or email today!