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SELECT THE ONE FOR YOUR LAB – Oscar Zavaleta Weighing Industry

Miss these Guidelines and you may Waste Time & Money

To select the ideal microbalance consider 3 factors. First, establish the sample’s state of matter and phase transitions. Next, determine if it is a dynamic or at rest measurement. Finally, specify the largest and smallest sample sizes.

PHASE Steady state samples benefit from conventional balance: SLS. Thermogravimetric mass analysis requires TGA  instrumentation. Dynamic vapour deposition benefits from TEOM systems.

INSTRUMENTATION

SLS: Solid & Liquid Samples Common laboratory mass samples in a solid or liquid state. The design does not allow for aerosol mass determination. Instrument Video: 1’23” https://lnkd.in/gxyGhAwm

TGA: Thermogravimetric Analysis Continuous thermal mass sorption analysis over time. Results for: ab/ad/des-sorption, phase change, redox, … Animation Video: 4’33”https://lnkd.in/gxniZHNp

TEOM ™ Tapered Element Oscillating Microbalance Real time aerosol mass particles detection. Sensitive to mechanical noise and temperature change. Operation Video: 1’29” https://lnkd.in/gYBmyayH

SAMPLE SIZE Determine the maximum and minimum sample sizes. Establish the accuracy level for those samples. Calculate the maximum allowable accuracy tolerance.

CAPACITY Available in single capacity and multi-range capacity. Multi-range capacity models tend to compromise accuracy. Resolution usually maxes out at 7 orders of magnitude.

RANGES vs RESOLUTION Hundreds: 250 g – 100 g     Semi Tens:           50 g –   10 g    Micro Units:             6 g –     2 g    Ultra

REPEATABILITY It determines the highest achievable accuracy. Accuracy can only be as consistent as your repeatability. Specified as percent of capacity: a) 5% b) 100%

CALIBRATION Instrumentation accuracy depends on the mass class it is adjusted with. Internal calibration is a convenient method to calibrate on the fly. External calibration allows multi adjustment points and verification

CONSTRUCTION Basic units consist of a unified weighing chamber and display control unit. Advanced models have separate weigh modules along with detachable displays. Modular designs reduce electric noise and provide user convenience.

TRANSPORTATION Always transport a microbalance on a pallet or equivalent. Equipment may be subject to permanent damage if shipped as a box. Damage may hide under linearity or random accuracy error.

CREDITS: The equation derived from one of Mettler’s online documentation. The standard deviation image has been extensively modified. https://lnkd.in/g5-MYNmh

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