CHOOSING THE BEST VALVE BAG PACKER : THE COMPLETE GUIDE

Thursday, July 21, 2016

At the turn of the 20th century, the valve bag was invented by Adelmer M. Bates, a salesman of salt. The story is that he was selling more salt than his company could deliver, and the filling method of the day seemed to limit his sales commissions. Once the bag was developed, Mr. Bates then started a venture to develop equipment to fill his new bag. Since that time, five basic machines have evolved to handle the broad range of products filled into valve bags:

• Air Packer (also called Force Flow)
• Auger Packer
• Gravity Packer
• Impeller Packer (also called Jet Flow)
• Vacuum Packer

Though many granular or pelleted products can be effectively filled into valve bags, the largest use of valve bags have centered around powdered products or mixes including powders. Because the opening of a valve bag is much smaller than that of an open mouth bag, the flow of the powdered product can be better controlled.

The earliest advantage of valve bags was that they were self-closing and reduced the labor required to fill and close (hand sew) the open mouth sacks of the day. Despite many innovations in the valve design including film lock and double trap, the self-closing feature is far from a hermetic seal. For this reason, many of the bags used in the chemical and food industry are ultrasonically sealed after filling. Other advantages of the valve bag include a more tightly filled bag and a squarer bag that will often make a better stack on the pallet (in comparison to other bag forms like open mouth and form-fill-seal).

Mr. Bates’ original valve bag was made of cloth. The vast majority of valve bags today are made of multiple plies of paper with an optional poly ply. Though valve bags can be made of polyethylene or woven polypropylene, the majority are paper.

Of the five equipment types mentioned above, four are used regularly. The gravity packer is rarely used as it works best with granular or pelleted products and these products can better be filled with open mouth or form fill-seal equipment. There is much overlap in the applications of these machines.

To assist with your choice, here are pros and cons of the remaining four machine types are discussed below:

Air Packer (Force Flow)

Air Packer (Force Flow)-2


PROS:

• Fast fill
• Good accuracy
• Versatile – works with fine powders and products with particle sizes up to 3/8”
• No moving parts in product stream
• Gentle handling of product – no mechanical shearing, minimal degradation
• Easy to clean out – drop bottom and chamber is accessible

CONS:

• Adds air to product during fill
• Risk of bursting a bag as bag is filled under pressure
• Does not handle very light products well (<10 pounds per cubic foot)
• Does not handle “sticky” products well (like bakery mixes with fat content)

Auger Packer

PROS:

• Little air is added to the product during fill
• Rarely bursts a bag as the bag is not filled under pressure
• Few adjustments – easily understood mechanical fill method
• Versatile - will handle a wide range of products – including difficult “sticky” products like bakery mixes with fat content

CONS:

• May require violent settling to tightly fill a bag
• Fluidized powders can flood past the auger even when the augeris stopped
• Typically slower than other filling methods
• Few ways to tune the machine to ideal settings for multiple products
• Subject to abrasion – wearing components in the product stream
• Can cause mechanical shearing and degradation of product

Impeller Packer (Jet Flow)

Impeller Valve Bag Filler-4

PROS:

• Fast filling of most powders
• Tightly filled bags

CONS:

• Limited product range – 200 mesh and finer particle size
• Difficult to clean (prior to a product changeover)
• Subject to abrasion – wearing components in the product stream
• Can cause mechanical shearing and degradation of product
• Adds air to product during fill
• Risk of bursting a bag as bag is filled under pressure
• Some products can cause heat in the impeller housing – product scorching is possible

Vacuum Packer

Vacuum Valve Bag Filler-5


PROS:

• Handles very light products well (< 10 pounds per cubic foot)
• Produces a tightly filled bag
• Gentle handling of product – no mechanical shearing, minimal degradation
• No moving parts in product stream
• If a bag bursts during fill, product is contained in vacuum chamber – environment remains clean

CONS:

• Difficult to fill into a bag that has a poly barrier ply
• Slow fill
• Expensive compared to other filling methods
• Can burst bags during fill

In general, Air and Auger packers are used for Food, Chemicals, Minerals, and some types of Feed. Impeller packers are used mainly for Minerals while Vacuum packers are used mainly for Chemicals. Though it is wise to consider first the machines traditionally used for your products, you may also want to consider the unique benefits of a specific machine type. Most equipment manufacturers offer testing services to help you decide what machine is best for your product and your needs.

The following is a rudimentary diagram that can be used to determine a possible machine for your product.

Tableau Choose A Packer En

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