LRS Micro-g LaCoste FG5, Manual, Page: 57 / 149

Adjustment and Maintenance
4
4. Adjustment and Maintenance
NOTE: The FG5 has been engineered to use metric screws and dimensions
wherever possible. However, some “off-the-shelf” purchased components use
English screws and dimensions.
4.1. The Dropping Chamber
4.1.1.REPLACEMENTS AND
ADJUSTMENTS
4.1.1.1.Removing The Dropping Chamber Cover
When opening the dropping chamber, take great care not to contaminate the
inside surface of the chamber cover or any of the interior parts. Always wear
clean-room gloves when handling internal parts. If any of the parts are
contaminated, clean the part using accepted vacuum system cleaning procedures
before reassembly. When performing repairs in the field, it is sufficient to wipe
or flush the contaminated parts with alcohol. Whenever possible, vent the
chamber with dry nitrogen rather than air. This will reduce the pump down
time after the chamber is reassembled.
To vent the dropping chamber, remove the clamp and blank flange from the
vacuum valve on the service ring. Loosen the vacuum valve lock ring and
slowly open the valve by rotating the control knob, allowing the chamber to
return to atmospheric pressure. It is best to vent using dry nitrogen, but it can be
directly vented to air. In any case, try to ensure that the gas entering the
chamber is free of particulate matter.
Remove the six screws holding the top flange to the top of the dropping chamber
cover, and remove the flange. Loosen the four snubber lock nuts and back out
the screws which position the top ring of the dropping mechanism within the
4-1