Post-Pelleting Liquid Application: A Practical Guide: Part 3
Quality Assurance & Automation
Quality control issues are of the utmost importance. The application must tie together into a robust automated system. The control system must fit into the automation objectives of the feed mill. Today many mills face the challenge of adopting HACCP and "Good Manufacturing Practices" to their day-to-day milling operations. The liquid addition system should fit into this process with routine checks and balances in place.
Some high attention detailing includes:
- Recharging of the enzyme day tanks and proper labeling of the tanks itself
- Lot number recording
- Balance the inventory of the liquid sprayed to the feed produced
- Periodic spot calibration
- Periodic finished feed sample taking proving the consistency of the application
- General maintenance of the equipment
No assumptions should be made when applying critical ingredients. Alarms should be included to alert operators of any possible malfunctions.
The control loop should include:
- Low or empty tank levels
- Low or no liquid flow
Like all systems, the automation should include the ability to expand enabling the addition of future liquids. Basic reporting will enable the feed mill to reconcile inventory and prove the application. In short, to obtain accuracy and homogeneity, the flow of liquid and feed must be in close harmony. The use of a process control system to run dependable software is the only way to achieve this goal.
Liquid application of feed additives may give a solution, in many cases, to making the ready product assortment more flexible. This will cause an extra capital investment that can be earned back by better efficiency and a larger product assortment (Copps, 1997).
Post-pelleting systems can be dependable. In principle, there is a choice between an advanced system that guarantees high accuracy and a cheaper, simpler system, which may always lack accuracy and uniformity. There is a wide range to choose from, and in most cases the best system will be a compromise between the two extremes.
The performance of any post-pelleting system should be judged on the uniformity and accuracy of liquid application, reliability, frequency of maintenance and ease of use (Chemgen, 1999). Some suppliers have underestimated this task, while others have met the demands of today's feed industry. The use of heat sensitive liquid ingredients in feed manufacturing will continue to increase as more ingredients become available in liquid forms. The challenge will be to successfully and economically adapt application of these liquids to bypass the excessive temperatures of pellet mill conditions and expanders.