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How does conveying line length affect trim removal system efficiency?

We're doing a series of blog posts about how inline cutter systems (cutter/fan systems) efficiently convey, process and remove continuous edge trim and waste filaments. Part 3 discusses inline cutters. Part 4 explores conveying lines.

Conveying lines connect the inline cutter with the material handling fan, and the material handling fan with the air-trim separator in a cutter/fan trim waste removal system.




Smaller Lines Means Lower Initial and Ongoing Costs

Shops have an opportunity to save money when using inline cutter systems for continuous trim waste removal vs. conventional venturi systems, because conveying lines carrying cut materials can be smaller.

Using the smallest possible conveying lines will reduce investment and installation costs. The minimum line size is dictated by the size and physical characteristics of the trim or filaments and the pressure drop that the fan can handle. The line pressure drop is directly proportional to the square of the conveying velocity and inversely proportional to the line size.

Cut trim or filaments are much easier to convey and cause lower pressure drop than continuous trim or filaments because they don't cause bend drag.

Using the small conveying line sizes that are practical with these cut materials results in savings beyond those associated with buying and installing the small conveying line. The airflow required to develop the recommended 5,000 feet/minute conveying velocity is inversely proportional to the square of the line size.

For example, a 6-inch line requires an air flow of approximately 982 CFM to develop 5,000 feet/minute velocity, while a 12-inch line requires 4 times this airflow, or 3,928 CFM, to develop the same 5,000 feet/minute conveying velocity.

Reduced air flows result in substantial savings on those system components with installation and operating costs based on the volume of air to be handled.


• The material separator at the discharge end of the line will be sized and priced according to the system air flow. The lower the air flow, the smaller and less costly the material-air separator will be.

• Filtering of the air discharged from the system is becoming more common to meet the increasingly stringent environmental standards for particulate emissions. Filter cost and servicing costs of the filter are directly related to the volume of air being handled. Filters for low-airflow systems cost substantially less than those for high-airflow systems.

• A considerable energy loss results when trim and the conveying air are picked up in a room in which the air is cooled, heated, filtered or otherwise conditioned, and discharged to a non-conditioned area. The lower the airflow in the trim system, the lower these losses will be. Lower energy losses lead to lower energy costs.

These savings provide a strong economic incentive to utilize the recommended small conveying lines, an inline cutter and a low-flow material handling fan.

Part 5 of our series explores how material handling fans can save you money.

Contact PAC to learn more about in-line cutter systems.


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