The days of dealing with the drudgery of manual volume measurement is finally a thing of the past!  AGR’s new SPT2™ automated testing system not only provides reliable and robust burst pressure testing, but it also delivers the means to perform accurate and repeatable volume measurement of glass container production on the factory floor.

Volume measurement plays an important role in the production of glass bottles.  Not only is it an important quality check and a verification of regulatory compliance, but it is key indicator of the status of the production process.    Accurate and timely volume measurements on a continuous basis through the entire production run can play an important role in the early detection and correction of process-related issues, helping to ensure consistent, high quality product and an efficient production process.

AGR’s new SPT2 provides brimful volume, fill point at a defined volume and volume at a defined fill point all in a single, automated test cycle on the factory floor.  The automation delivers real productivity gains when compared to current manual methods performed in the laboratory.  For example, the SPT2 performs a volume measurement of a typical beer bottle in 30 seconds from start to finish.  This includes handling the bottle, measurement, data capture and documentation.  Compared to an average of 2+ minutes for volume measurement in the laboratory using the gravimetric method, the SPT2 provides a 4x increase in productivity and throughput, all without the constraints associated with traditional laboratory testing.  In addition, with a few extra seconds, further savings can be gained when bottles are pressure tested immediately following volume measurement.  If the system is integrated with an automated sampling system, additional efficiencies can be realized.  Furthermore, with automatic sampling, volume measurement can be staged throughout the day to occur between pressure testing jobs to maximize testing and take advantage of the efficiency of the system.

How it works

The volume measurement system incorporated in the SPT2 utilizes positive-displacement technology.   In simple terms, the positive-displacement approach employed by the SPT2 works as follows; a known volume of fluid is transferred from a temperature compensated, calibrated piston and cylinder into the test container.  At the same time, the fill level is dynamically monitored as the container is filled to overflow.

More specifically, the SPT2 incorporates a calibrated cylinder at the center of the volume station.  During the volume measurement process, a piston pushes water from the calibrated cylinder into the bottle.  A defined volume of water, relative to the container size and specifications, is dispensed into the container.  The SPT2 measures the dispensed volume by tracking piston motion with a high resolution encoder.  As the container fills, the level of the water meniscus is measured by a high resolution displacement sensor.

The positive-displacement method offers a number of advantages.  Most significant is the accuracy. This filling technique, in tandem with a high-precision fill-height sensor makes it possible to deliver defined volume and fill measurements at any point within the process, to an accuracy of + 0.5 ml. This this is equivalent to a single drop of water!  Other advantages include little or no effect on measurement precision due to water quality, container shape or rate of fill, regardless of the size and volume of the container.  Furthermore, the volume measurement system on the SPT2 is self-contained, requires no delicate scales and is not affected by water density, flow rate, vibrations or issues that commonly plague other methods.

Non- round containers

Non-round containers present their own unique challenges when it comes to capacity.  Non-round volume can vary dramatically as a result of subtle changes in the process. Heavy corners, sunken or bulged panels are some of the issues that can dramatically affect capacity and result in fill point and overflow volumes that are out of specification.  With non-round containers, especially spirit bottles, managing capacity is critical.  The SPT2 universal gripping system is able to handle a wide range of non-round shapes and sizes.  Measurements are performed in the same manner as round bottles at the same levels of accuracy.

Pressure testing

In addition to high precision volume measurement, Agr’s SPT2 also provides burst pressure testing. The pressure testing component of the SPT2, offers a solution to overworked testing laboratories and a need to maintain a continuous regimen of pressure testing 24/7. The SPT2 features an advanced, controlled-velocity pressure generation system that can pressurize containers up to 1000 psi (1 minute equivalent) while providing extremely accurate and controlled pressurization throughout the testing process.  The system is designed specifically to meet industry testing requirements per ASTM C-147 and ISO 7458. The SPT2 incorporates a number of advanced features designed to simplify testing and improve plant efficiency.  Some of the features include a high throughput rate of 270+ bottles per hour (when volume is not measured), a universal gripping system that can accommodate a range of bottle finishes up to 38mm and dynamic adjustment for bottles of varying diameter and height without job change. Jobs can be setup to perform proof or full burst tests, combined volume and pressure tests or just volume.  Since the SPT2 can perform in-process job changes, it is possible to test bottles from different manufacturing lines, or hand-feed a set of bottles as required, with testing protocols unique to that specific bottle type, without the need to stop and reconfigure the system, maximizing testing efficiency.

Whether set up for pressure only or pressure and volume testing, the SPT2 can be configured as a stand-alone testing station, integrated into a sampling line in conjunction with a plant-wide process management system or combined with Agr’s OmniLab^® automated measurement system.  When combined with the OmniLab^® system, pressure and volume as well as dimension, weight and thickness can be measured in a single hands-free operation with data correlated into one comprehensive report.