To fill a bag, bagging scales need a spout that fits inside the bag. The spout is determined by the application, the size of the bag, and the material of the bag. 


There are 2 basic types of spouts for open mouth bags: non-clamp and clamp.

Non-Clamping Spouts The non-clamp spout is a simple tapered funnel where the bag is placed over the bottom of the funnel and manually held in place as the bag is being filled. It is used with net-weigh systems. Non-clamp spouts are typically found on low throughput &/or small weighment (e.g. less than a few lbs.) systems.  

Clamping Spouts The clamping spout is a tapered funnel that clamps the bag on the spout. They are either a “clam shell” style or a “center grip” style. Clamping spouts can be used on either gross weigh or net weigh systems. Clamping spouts can be either mechanically or pneumatically operated. Pneumatic spouts are activated with a whisker switch or foot switch.

  •  Clam Shell Spouts Clam shell spouts are funnels that are split down the middle and each side expands outward to hold the bag in place. Clam shell spouts are typically used with heavy poly bags because of their larger clamping area.
  • center grip spoutCenter Grip Spouts Center grip spouts are most common and have two curved “arms” that clamp the bag on the spout after it is placed on the spout. Center grip spouts are typically used with paper or poly-woven bags.


There are options that may be available with a spout.

  • dust tight spoutDust Tight The dust tight option for the center grip spout is a fabric band that fully encircles the top of the bag when clamped.
  • Dust Accumulation The dust accumulation option is a 2” port where a vacuum system is attached to evacuate dusty powder created as the bag is being filled.

 Material Selection

Spouts are available in mild steel or stainless steel. Stainless steel spouts are used with corrosive materials (such as fertilizer or salt) and with food or pharmaceutical products.

 Spout Size Determination

Spouts come in a wide variety of sizes. The size of the spout is determined by the circumference of the smallest bag being filled. To determine the circumference of the bag, lay it flat and measure its width and multiply by 2. Be sure to include any gusset. For example, a 12” wide bag with a 2” gusset will have a 28” circumference (2 x 14”). To be able to spout that bag you will need an additional 5“ clearance. Therefore your minimum spout circumference is 33” (28+5).        

For more specific recommendations, contact us at 1-608-221-8180 or [email protected].