Issue link: https://www.e-digitaleditions.com/i/962670
18 April 2018 Tablets & Capsules passing flowrate check and get the coating system back in operation, it's a time-consuming process that leaves the company behind schedule. Solution delivery system setup Over the years, I've been asked to troubleshoot many coating solution delivery systems and have developed a procedure for optimizing system setup and single-tube Coriolis flow meter performance. Note that, while this information primarily concerns flow meters being used with tablet coating systems, the principles are nearly identical for any process—such as spray granulation— that uses a single-tube Coriolis flow meter. A coating solution delivery system typically consists of a coating solution tank, a solution supply tube, a peristaltic pump, an automated shut-off valve, a single- tube Coriolis flow meter, a manifold, and several spray guns. It's important that the coating solution tank's discharge be located at the bottom of the tank. Since the peristaltic pump performs most of its work getting the solution from the tank to the pump, more head pressure in the tank—along with as large a supply-tube diameter and as short a distance between the tank and the pump as possible—means less work for the pump. A ball valve is typically attached to the tank discharge, and the solution mass flowrate for the pharmaceutical industry because it accounts for the constant changes your solution is subjected to as well as any environmental changes occurring during the coating process. For volumetric flowrate, a single-tube Coriolis flow meter uses the solution's temperature, pressure, viscosity, density, and percentage of solids to accurately calculate flowrate. As a result, if the flow meter is set up properly and re-zeroed after being primed with your solution, volumetric flowrate measurements are more accurate than mass flowrate measurements by approximately 0.1 percent, though this rating may vary depending on the flow meter manufacturer. The pharmaceutical companies I've worked for have often had unidentifiable long-term coating solution flowrate issues. One company even worked around these issues by consistently performing flowrate checks before each batch until one of the checks passed. If the company couldn't get a passing result, the metrology department would recalibrate the flow meter using water. Recalibrating a single-tube Coriolis flow meter with water requires that the meter be cleaned so that metrology can install dedicated calibration instruments, re-zero the meter, and perform a flowrate check. While recalibrating the flow meter will almost always result in a Pump element selection The tables below show some of the pump element sizes (inside diameter) available and the recommended flow- rates at various coating-solution solids percentages for each. Most pump elements are rated at 10,000 hours, but that rating is likely based on a bench test pumping water into a sink, which is a best-case scenario and yields results that are likely higher than you will achieve using the tubing in a real application. I recommend changing pump ele- ments after every tableting campaign, especially if you're spraying a solution with a solids percentage greater than 10 percent or a viscosity higher than that of water. 1.6-millimeters Solids percentage Recommended flowrates (mL/min) Low Optimal High 0 0.040 47 95.000 10 9.536 38 85.504 15 14.284 33 80.756 20 19.032 28 76.008 4.8-millimeters Solids percentage Recommended flowrates (mL/min) Low Optimal High 0 0.420 465 930.000 10 93.378 372 837.042 15 139.857 325 790.563 20 186.336 279 744.084 9.6-millimeters 6.4-millimeters Solids percentage Recommended flowrates (mL/min) Low Optimal High 0 0.700 750 1,500.000 10 150.630 600 1,350.070 15 225.595 525 1,275.105 20 300.560 450 1,200.140 8-millimeters Solids percentage Recommended flowrates (mL/min) Low Optimal High 0 0.900 1,000 2,000.000 10 200.810 800 1,800.090 15 300.765 700 1,700.135 20 400.720 600 1,600.180 3.2-millimeters Solids percentage Recommended flowrates (mL/min) Low Optimal High 0 0.230 250 500.000 10 50.207 200 450.023 15 75.196 175 425.035 20 100.184 150 400.046 Solids percentage Recommended flowrates (mL/min) Low Optimal High 0 1.300 1.300 2,800.000 10 281.170 281.170 2,520.130 15 421.105 421.105 2,380.195 20 561.040 561.040 2,240.260