Dr. Jae Park of Oregon State University's Seafood Laboratory in Astoria, Oregon requested that we design a fixture for testing the viscosity of surimi paste. We would like to thank Dr. Park and Dr. B.Y.Kim for providing formulas for the analysis that follow academic and industry standards and for their suggestions on how to port those formulas to the TA.XTPlus. We customised a previous capillary fixture to suit Dr. Park's requirements and the characteristics of OSU's surimi paste. We designed the rig's openings and nozzle lengths for suitability for a broad range of products and also created an Exponent project and test sequence to allow products to be tested at multiple speeds in a single stroke. We then benchmarked the fixture against standard viscosity fluids.

TA-525 Capillary Fixture Kit
The TA-525 capillary fixture kit can be used for quantifying the apparent viscosity of fluids and pastes. Our standard model capillary fixture comes with interchangeable 10 mm and 30 mm long extrusion tubes and nozzle diameters that are 2.5, 5.0 and 7.5 mm in diameter. The rig comes with an "Exponent Project" file that the user can immediately use to program the Plus or HDPlus to extrude the product at up to seven different speeds during a single downward stroke. The rig comes with an Excel spreadsheet with built-in assumptions on the fixture's dimensions and calculates the "C" or "K" value (Consistency Index) and the "n" (Flow Behavior Index) for power law fluids. The spreadsheet also plots the shear stress vs the shear rate for the range of rates that the product was tested with.

The standard rig, when mounted on a TA.XTPlus with a 50kg load cell, is good for materials of up to approximately 400,000 cp. We can customize the openings to be wider than 7.5 mm diameter for use with the TA.XTPlus when testing thicker materials. The TA-525 Capillary Fixture can be used in conjunction with SMS' TA.HDPlus to extrude materials at much higher pressures. The TA-525 Capillary Fixture Kit includes the piston, six extrusion nozzles, a plunger, an extrusion disk, shorter replacement legs for use with a client's TA-90 heavy duty platform, and a software disk with the Capillary Project files and the Capillary Calculation Template in Excel format.