Microtrac S3500, Operation And Maintenance Manual, Page: 28 / 38

22 Microtrac S3500 Particle Size Analyzer Operation and Maintenance 9/03
3.4.3 Running a Sample
Before running a sample, be sure that all hardware components are properly connected and ready to
operate. Making a measurement is an interactive process involving the user, the S3500 analyzer and the
sample delivery device. The process is coordinated by the Microtrac application software. Follow the
instructions in the Microtrac application software manual to conduct a run. The “Quick Start” section of
the software manual is recommended when becoming familiar with the S3500 analyzer system.
3.5 Collector Lens Change
The S3500 Enhanced System is capable of measuring particles as large as 2800µm. Samples containing
particles larger than 1400 µm require the use of the long collector lens. The long collector lens may be
used with samples as small as 0.02 µm, but accuracy is substantially enhanced by using the short collector
lens for these applications.
Removal
Remove the top cover of the optics module by loosening the knurled thumbscrews. Engage the lens
wrench in the face of the lens retaining nut as shown and rotate it toward the front of the S3500. If it was
over-tightened before, it may be necessary to tap lightly on the wrench to loosen the nut. Loosen the nut
only until it turns freely on the lens body.
Rotate the lens approximately 1/3 turn counter-clockwise until it stops. The three locating lobes are now
aligned with the slots in the optics housing, and the lens can be withdrawn. Use care to protect the lens
surfaces. It’s a good idea to put the lens cover(s) from the replacement lens on the lens you have removed.
Installation
Check the lens for dirt, smudges or fingerprints. Clean only when necessary using the procedure described
in section 4.2. Temporarily re-install the rear lens cover to protect the lens during installation.
The lens can be inserted only one way. One of the lobes on the lens has a depression on its edge. Hold the
lens as shown with the depression facing you and insert it through the housing wall. When inserting the
long lens, ensure that the lens body does not contact the small mirror mounted in the housing. Rotate
clockwise until it stops. Turn the lens retaining nut clockwise until it is snug – do not over-tighten.
Remove the rear lens cover. Re-install the optics module cover.