Instruction manual

High Throughput Diffusion Pumps
44
DRAFT 12/23/04
NHS-35 Jet Assembly
Figure 29 NHS-35 Jet Assembly
To disassemble the jet:
1. Unscrew and remove the hex nut holding the cold
cap in place. Note its orientation prior to removal
2. Remove the cold cap (or halo baffle) as described in
“Cold Cap” on page 38.
3. Unscrew the top jet cap and remove.
4. Remove the spacer and top jet orifice plug.
5. Lift the second stage and jet shield over the center
threaded jet rod.
6. Using the two eyebolts now accessible and
appropriate lifting equipment, lift the entire lower jet
assembly out of the pump body, leaving the jet rod in
place.
7. Remove the third stage jet shield.
8. Remove the securing nuts and lift the third stage and
fractionating tube off the fourth stage.
9. Remove the fourth state jet shield.
10. Remove the securing nuts and separate the fourth
stage from the jet base.
11. Clean and service as needed.
To reassemble the jet:
1. If the center jet rod was removed or loosened during
disassembly, thread the rod back into the boilerplate.
The top of the rod should be roughly 1/16" to 1/8"
below the top surface of the inlet flange (inlet plane
of the pump). Once properly located, use the nut
near the boilerplate to lock the rod in place.
2. Reverse steps 7 through 10 above to reassemble the
lower jet assembly.
3. Using the two eyebolts and the appropriate lifting
equipment, lower the lower jet assembly into the
pump body over the jet rod. The ejector should be
aligned directly across from the foreline. A locating
slot on the jet base engages a block in the pump
body to ensure the ejector is properly aligned with
the foreline.
4. Reverse steps 1 through 5 above to reassemble the
upper jet components.
Water-Cooled
Shields
Lugs to Lift
Main Jet Assembly
Cold Cap
CAUTION The jet will not seat properly and the
pump will not function unless the slot is
engaged on the locator block. Check
the engagement by attempting to rotate
the jet once in place.
NOTE The top jet orifice plug must be seated
in the tube with the machined relief
down into the tube. Ensure that the plug
is not installed upside down.
NOTE The hex nut is installed such that the
small diameter acts to center the cold
cap or halo baffle. Ensure that the hex
nut is not installed upside down.