Issue link: https://www.e-digitaleditions.com/i/962670
Tablets & Capsules April 2018 19 supply tube is attached to the ball valve. I recommend using braided hose for the supply tube to limit the pulsing effect created by the peristaltic pump. The other end of the supply tube attaches to a barbed fitting on the end of the peristaltic pump element. Most peristaltic pump elements use special tubing designed to handle millions of compression cycles from the pump's rollers during operation. Unlike most tubing, peristaltic pump elements are designed to quickly regain their shape after each pass of the roller. The peristaltic action of the rollers against the pump elements is what moves the coating solution through the supply tube, but it also causes additional frequencies to pass through the solution to the flow meter. If these frequencies are irregular and inconsistent, they can impact the flow meter's measurements or even cause the meter's zero point to drift. To minimize these additional frequencies, I recommend using a double peristaltic pump. Instead of having a single tube element passing through the pump, a double peristaltic pump has a double tube element. A barbed Y fitting splits the single supply tube coming from the tank into two separate tube elements that pass through the pump. The double tube peristaltic pump has a specially designed cover that fits over the rollers to create an engineered offset that prevents the pump from cycling both tubes simultaneously. This offset minimizes the frequency fluctuations generated by the pump and keeps the flow meter readings more consistent. At the exit of the peristaltic pump, another barbed Y fitting merges the pump's two tube elements back into a single supply tube. I recommend Watson-Marlow double peristaltic pumps, which are widely used, and double Gore Sta-Pure tubing elements. (Note that using Sta-Pure tubing elements with a Watson-Marlow 505L pump head requires that you use a different spring setup, called a 505-LG.) It's important to have a preventative maintenance plan in place to keep your pump in top condition. You should regularly check the pump head and rollers for play, which can impact flowrate accuracy. With the unit locked out, you shouldn't be able to rotate the pump head in either direction. Check each individual roller for play and free movement. The rollers should spin freely but shouldn't have play in any direction (up, down, left, right, in, and out). Any play will impact your flowrate, and continuing to run a pump that has play in it will ultimately damage the pump's gearbox. The pump continually adjusts its speed to maintain the desired flowrate based on feedback from the flow meter. Usually, these speed adjustments are so minimal that they're hard to detect by looking at the pump. However, if there is any play in the pump, these minor adjustments can create inconsistencies in the vibration frequencies read by the flow meter and cause the meter's zero point to drift. From the peristaltic pump, the coating solution supply hose first goes to an automated shut-off valve that opens and closes as the spray system is turned on and off and then continues on to the flow meter. Dr. Schleuniger ® Pharmatron is a brand of Our new generation of tablet hardness and disintegration testers allow you to save time & money by maximizing the efficiency of your quality control process. Innovative technology paired with proven mechanics makes operation simple, reduces processing time, and provides precision results you can rely on. www.pharmatron.com Quality matters. How efficient is your quality control?