B344-21-880 Issue N
Page 38 © Edwards Limited 2007. All rights reserved.
Edwards and the Edwards logo are trademarks of Edwards Limited.
Maintenance
5.5.3 Remove the high-vacuum isolation-valve (P-model pumps)
1. Open the valve pneumatically and then disconnect the pneumatic pipelines from the Diffstak.
2. Remove the socket-head screws which secure the valve-plate to the shaft and detach the valve-plate.
3. Remove the valve-shaft:
z On Diffstak 63/150P and 100/300P pumps: Detach the red safety cover from the pneumatic actuator and
remove the three screws which retain the actuator to the boss on the valve-body. Carefully withdraw the
valve-shaft (complete with actuator) from the valve-body (see Figure 22).
z On Diffstak 160/700P pumps: Detach the red safety cover. Remove the two screws which retain the switch
mounting bracket to the valve-body and detach the bracket. Unscrew the grub screw (M3) in the link arm and
remove the pin in the cylinder. Disconnect the pneumatic cylinder. Withdraw the valve-shaft from the body
(see Figure 23).
z On Diffstak 250/2000P pumps: Detach the red safety cover. Remove the two screws which retain the switch
mounting bracket and remove the circlip from the cylinder pivot-pin. Withdraw the valve-shaft from the
body complete with the pneumatic cylinder and linkage (see Figure 24).
5.5.4 Dismantle the pump
1. On Diffstak 63/150 pumps, slacken the single screw which retains the baffle-cap strap; on other pumps, slacken
the two screws which retain the baffle-cap strap. Rotate the strap to release it.
2. Withdraw the baffle-cap from the Diffstak; use the grips provided to ease the baffle-cap through the bore of the
valve-body.
3. Remove the interior jet assembly:
z On Diffstak 63/150, 100/300 and 160/700 pumps: Remove the spring from the first-stage jet-cap then insert
the extractor tool in the threaded hole in the boss (grip the boss on the Diffstak 160/700 jet-cap) and lift out
the complete interior jet assembly from the body.
z On Diffstak 250/2000 pumps: Unscrew the top-jet cap then remove the second and third-stage sections
separately.
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