Syringe Force Tester
The Syringe Force Tester can be used to evaluate empty or pre-filled syringes in a wide range of sizes. Fixtures can be adapted for syringes with or without needles attached including staked needles. The fixtures are designed to safely collect the expelled contents of the tested syringes.
The instrument is robust in design, easily cleaned, encased in stainless steel and is suitable for, development or quality laboratories or in sterile suites adjacent to aseptic filling lines.
The syringe forces are measured by applying strain (compression) at a fixed rate to the plunger within the syringe barrel and collecting strain (distance) versus stress (force) data. Numerous data points are collected graphically displayed as a stress: strain curve. The graph shows force in Newtons or pounds of force on the y axis and distance in centimeters or inches on the x axis. The peak is identified and recorded as the break loose force. Subsequent data points are isolated to identify and accurately calculate the glide force using a proprietary data analysis algorithm.
The force readings are completely objective; no subjective evaluation by the operator is needed to determine the peak or where to measure the glide force.
The syringe to be tested is placed in a fixture that is specific to the syringe dimensions and configuration. The fixture secures the syringe and centers it over the force transducer. An appropriate sized rod is secured into the press arm and centered on the syringe. The press arm and rod are jogged down into position over the syringe plunger. The syringe is ready for testing.
The operator then touches the run icon on the PLC screen. The data collection, analysis, and reporting process proceeds automatically under control of the PLC. After initialization, including reading the current force reading to zero the applied force measurement, the press arm and rod start downward movement, at a controlled speed, contacting the syringe plunger.
A force reading is taken approximately every 0.001 inches (0.00254 cm) of travel at the default speed of 100cm per minute.* This continues until the force increases as the plunger bottoms out. At this point the press arm and rod return to a position that allows easy removal of the tested syringe.
The data points are automatically plotted and analyzed. The graph is displayed on the PLC screen. The operator has the option of printing the screen data or exporting the force results and sample identification to a separate computer spreadsheet via a USB connection. Using another mode all the raw data points can be exported via USB to a spreadsheet or data base. Templates can be designed in these systems to recreate the graphs and calculations. This application may be useful for validation and research purposes.
The set-up and operation of the instrument is simple. Once set-up each individual test can be completed in less than a minute, including the placement and removal of the syringe from the fixture. Within the system is a calibration mode. In this mode force, position, and speed are continuously displayed on the PLC screen. This allows the calibration technician to perform calibration functions and compare readings to a separate traceable calibrated force gauge.
Validation can be accomplished by comparing on screen results with those downloaded to a spreadsheet and performing appropriate evaluations of the data for the syringe system being tested. No test data or results are stored in the unit. To comply with cGMPs and 21CFR part 11 data should be downloaded into compliant database systems.
The force profile and break loose and glide force results provide useful information in evaluating syringe system design and functionality. The Syringe Force Tester can be used to evaluate syringe system components and the effects of variation and interference fit as well as the effects of different coatings, methods and levels of siliconization, needle gauge, and formulation viscosity.
It can provide data for system development, incoming quality control, and monitoring process variability.
