Micromeritics Elzone II 5390 Operator's Manual page 370

Appendix H
Vibration and Acoustic Noise
Vibration and acoustic noise produce electrical signals much like those produced by a
microphone. This usually results from the combination of a small orifice in the sample
tube and a viscous electrolyte solution. As the size of the orifice decreases, the voltage
drop across the orifice during operation increases. The higher the voltage, the more sus-
ceptible the system is to microphonic pulses. These pulses may be due to vibrations
transmitted into the beaker of electrolyte through the hardware of the instrument, created
by the vacuum pump, cooling fan, stirrer, or transformed from air-borne acoustic waves.
In addition, as the conductivity of the electrolyte decreases, the voltage drop across the
orifice increases, again resulting in greater susceptibility to vibration and acoustic stimuli.
Other operational factors that increase the sensitivity to these vibration sources are
increased viscosity or a very slow flow of the electrolyte through the orifice.
Improved Performance
The Elzone includes several features which help to control the occurrence of stray parti-
cle counts.
Software
The Elzone software contains certain analysis parameters that can be selected to help
minimize background counts.
Optimize Settings
Generally, the current should be set as high as possible. The amplifier gain settings
should be chosen to cover the desired particle size range. If the current is set too high, the
electrolyte may heat in the orifice enough to form air or vapor bubbles, which are
detected as particles. If the gain is set too high (to compensate for too low of a current
choice), noise inherent to the electronics is amplified and also detected as particles.This
noise results from Brownian motion of the ions in the electrolyte.
H-2
Elzone II 5390 Confirm
539-42822-01 (Rev A) - Nov 2017