BY Robert K. Haugen, Ph.D., Director of Product and Technology Development, Flow Sciences, Inc.
It is crucial in analytical environments that precise weighing takes place inside containment where potent powders being weighed do not escape into the lab. This is typically accomplished with a top-mount safety containment system such as the one shown below.
An effectively designed unit must have an exhaust fan and HEPA filter located at the top of the unit, and such a fan has an inherent vibration. If undamped, this vibration can significantly affect the accuracy and stability of the balance.
Any top-mount safety containment system must therefore accomplish two objectives which are at cross purposes: use air movement and a fan to accomplish protective containment while maintaining a vibration-free weighing zone to assure balance accuracy.
Flow Sciences incorporates a low vibration fan subassembly in its design by using a balanced fan, thicker low static pressure filters which put less strain on the motor, and a soft gasket junction between the fan subassembly and the containment unit.
The purpose of this paper is to measure the effectiveness of these three vibration isolation strategies.