Insufficient Product Yield - Pharmaceutical Technology

Latest Issue

Latest Issue
PharmTech Europe

Insufficient Product Yield

Equipment and Processing Report

Untitled Document

This issue marks the introduction of Equipment & Processing Report’s new “Troubleshooting” column. When a process does not produce the expected results, or when a piece of equipment behaves strangely, even experienced personnel sometimes may be at a loss to understand the reason why. This column will be a forum to discuss production problems. Readers will submit anonymous questions, which equipment vendors and industry professionals will attempt to answer. In this way, the column may help promote greater understanding of the industry's products and processes.

Q: Our dry-powdered product is not meeting a critical final-quality specification related to the particle-size distribution. We use a volumetric dry-material feeder and jet mill to create the finished product. When we charge the feeder hopper with a batch of material, the resulting particle-size distribution changes from the beginning of the run to the end of the run. Maybe the load in the mill (i.e., the feed rate through the system) drops off because the material is sensitive to head load and we have no feedback control on the material feed rate. Why doesn’t our particle-size distribution stay consistent throughout the run? How can we meet our final-quality specification?

A: Try performing additional testing in the laboratory using a gravimetric feeder, which has a scale that is monitored by a controller. The controller uses the data from the scale to calculate a feed rate and provide a feedback control loop to maintain a set feed rate.

It is indeed likely that your material’s flow properties are sensitive to head load, and without the feedback control loop, the feed rate drops off as the feed hopper empties. The control loop in the gravimetric feeder should be able to increase the speed of the auger. This increased auger speed could compensate for the change in material flow that results from the change in head load. Also, the increased auger speed could help maintain the feed rate for more than 95% of the hopper capacity. Using a gravimetric feeder that provides a feedback control loop could increase your product quality and yield.

—Chad Lorensen, business-development manager at Schenck AccuRate (Whitewater, WI)


If you have a problem with your equipment or process, an industry expert may have the solution. Please send your question to Erik Greb, editor of Equipment and Processing Report, and we may be able to provide an answer in a future issue. All questions will remain anonymous.


blog comments powered by Disqus
LCGC E-mail Newsletters

Subscribe: Click to learn more about the newsletter
| Weekly
| Monthly
| Weekly

Which of the following business challenge poses the greatest threat to your company?
Building a sustainable pipeline of products
Attracting a skilled workforce
Obtaining/maintaining adequate financing
Regulatory compliance
Building a sustainable pipeline of products
Attracting a skilled workforce
Obtaining/maintaining adequate financing
Regulatory compliance
View Results
Eric Langer Outsourcing Outlook Eric LangerBiopharma Outsourcing Activities Update
Cynthia Challener, PhD Ingredients Insider Cynthia Challener, PhDAppropriate Process Design Critical for Commercial Manufacture of Highly Potent APIs
Jill Wechsler Regulatory Watch Jill Wechsler FDA and Manufacturers Seek a More Secure Drug Supply Chain
Sean Milmo European Regulatory WatchSean MilmoQuality by Design?Bridging the Gap between Concept and Implementation
Report: Pfizer Makes $101 Billion Offer to AstraZeneca
Medicare Payment Data Raises Questions About Drug Costs
FDA Wants You!
A New Strategy to Tackle Antibiotic Resistance
Drug-Diagnostic Development Stymied by Payer Concerns
Source: Equipment and Processing Report,
Click here