The unit is comprised of a pneumatic cylinder, load cell, LVDT (linear variable differential transformer), thermocouple and host computer. As the pneumatic cylinder is energized by a command from the host computer, the ram head moves downward and squeezes a disk shaped specimen of material. During the squeeze the load cell measures the reaction force of the material against the ram head while the LVDT keeps track of the ram position as a function of time. A thin gauge thermocouple is inserted into the radial surface of the sample to measure temperature.

When the sample is fully squeezed within a minute the experiment is complete. The data collected is then fitted to a mathematical model and the system instantly outputs parameters of the shear viscosity material function, including characteristic “power law “parameters. A unique feature of this system is that the host computer is an embedded PC. This embedded system is comprised of a number of card modules that are stacked together to achieve the desired functionality. The embedded PC does not contain any moving parts and is thus largely maintenance free. The operating system, source code, and analysis program all reside on one of the card modules. Data may either be written to one of the modules or to a PCMCIA flash card, which can be removed from the system with ease. A touch screen and Visual Basic interface are used for convenient control of the squeeze flow unit.

MP&R also has available an explosion-proof version of the squeeze flow rheometer, especially suitable for the energetics industry. The operator interface of the explosion-proof version consist of an intrinsically safe LCD display and three logic buttons for control. Historically, to test the consistency of propellants during a batch mixing process, the operator would remove a small sample of material from the batch mixer. The operator would then work the material back and forth between his or her fingers (small amplitude oscillatory shear) and determine if the batch needed more solvent or if it should be mixed longer etc. The squeeze flow rheometer solves such quality control problems by giving the operator quantitative information to work with which can also be monitored by the supervisory staff.