Reassembling Frg-700 - Agilent Technologies FRG-700 User Manual

Technical Information
Replacing the Pirani element
If it is severely contaminated or defective.
NOTE
1 Slide a new FPM seal (13a) over the Pirani element (13) and insert it into the
corresponding groove.
2 Mount the Pirani element.

Reassembling FRG-700

1 Insert the FPM seal (11) with the support ring (12) centered into the measuring
chamber (7). The sealing surface, seal, and ceramic part must be clean.
2 Carefully insert the anode (10) incl. ignition aid (10a) into the measuring
chamber.
3 Insert the Pirani element (13) with the FPM seal (13a) slid over it into the
corresponding bore hole.
4 Carefully place the pressure piece (9) on the measuring chamber and tighten
them with the three hexagon socket screws (8) incl. lock washers (8a) uniformly
until the stop position is reached.
5 Position the ignition aid (10a) by pushing the mounting tool over the anode pin
until the mechanical stop is reached.
6 Blow the particles in the measuring chamber with dry nitrogen (be careful to
hold the measuring chamber with the flange pointing downwards).
7 Slide the polarity insert (6) into the measuring chamber until the mechanical
stop is reached.
8 Place the circlip (5) snugly fitting on the polarity insert.
Visually check that the anode pin is centered over the middle hole of the polarity
NOTE
insert (max. eccentricity = 0.5 mm).
9 If possible perform a leak test (leak rate <10
WARNING: electric arcing.
WARNING
Helium may cause electric arcing with detrimental effects on the electronics
of the product.
Before performing any tightness tests put the product out of operation and
remove the electronics unit.
38 Agilent Inverted Magnetron Pirani Gauge FRG-700 and FRG-702 User Manual
-9 mbar l/s).