Micromeritics Elzone II 5390 Operator's Manual page 259

Preventive Maintenance
Preventing Orifice Blockages
Sample materials are seldom sources of fibers or debris in sufficient amount to cause fre-
quent blockages. If blockages do occur due to sample materials, you can "scalp off"
debris by wet-sieving the prepared suspension through a clean mesh that is roughly 75%
of the orifice diameter.
At all times, there must be no substantial source of dust or debris:
• in the outer surface of the orifice tube or inner surface of the sample beaker
• on the operator's hands or clothing
• on the instrument or bench-top
• in the ambient air
A good technique is to filter the electrolyte properly through a 0.1-m microporous mem-
brane. Clean all surfaces in contact with this filtered electrolyte with detergent and then
rinse two to three times with the filtered electrolyte.
Do not use towels to dry sample beakers. Keep sample beakers covered or inverted on a
clean surface.
Stress Cracking of Orifice Jewel
The orifice jewel seal is a ceramic bonding of synthetic sapphire and glass which with-
stands virtually all chemicals. By nearly matching thermal expansion coefficients, the
bonding is strong but can, in time, develop stress cracks in the glass around the jewel,
which may cause a noise signal. Repeated cracking will require remount of the jewel in
new glass or replacement of the orifice tube.
Check the orifice jewel periodically for signs of cracking. The illustrations below show
the jewel portion of the orifice tube. The illustration on the left shows a jewel in good
condition while the one on the left shows a jewel that has begun to crack.
This is a jewel in good
condition.
539-42822-01 (Rev A) - Nov 2017
Cracking
This is the jewel of the same
orifice tube; note how it is
beginning to crack.
Elzone II 5390 Confirm
8-5