Reassembling Frg-702 - Agilent Technologies FRG700KF25 Operating Instructions Manual

6.3.3 Reassembling FRG-702

Inverted Magnetron Pirani Gauge FRG-700 FRG-702
( figure  24)










Insert the Pirani element (13) with the screw fitting (13a) and copper seal
(13b) slid over it into the corresponding conic bore hole (7) of the measuring
chamber.
Tighten the screw fitting (13a) with your fingers while slightly pushing the
Pirani element against the mechanical stop. Then tighten the screw fitting
by one turn with the open-end wrench.
Insert a new metal seal (11) incl. the centering ring (12) centered into the
measuring chamber (7).
Carefully insert the anode (10) with the ignition aid (10a) and extension
piece (9a) slid onto it into the measuring chamber.
Carefully place the pressure piece (9) on the measuring chamber.
Insert the four hexagon socket screws (8) incl. lock washers (8a) and
tighten them uniformly until the mechanical stop is reached.
Carefully slide the insulator (9b) onto the pressure piece (9) and lock it with
the hexagon socket set screw (9c).
Position the ignition aid (10a) by pushing the mounting tool over the anode
pin until the mechanical stop is reached.
Blow the particles in the measuring chamber with dry nitrogen (be careful to
hold the measuring chamber with the flange pointing downwards).
Slide the polarity insert (6) into the measuring chamber until the mechanical
stop is reached.
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 insert (max. eccentricity = 0.5 mm).
If possible perform a leak test (leak rate <10
retighten the screw fitting (13a).
WARNING
WARNING: electric arcing
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.
Mount the magnet unit (4) and lock it with the hexagon head screw (3).
Carefully mount the electronics unit (2). (Make sure the pin of the Pirani ele-
ment is properly plugged into the corresponding hole of the electronics unit.)
Push the electronics unit up to the mechanical stop and lock it with the
hexagon socket set screw (1).
Adjust the gauge (  18).
26
-9
mbar l/s). If necessary slightly