6/16/92 Jim Deacutis

Thayer School of Engineering

1.0 Important Preface:

This MS-90 Leak Detector has been reconfigured so that the valving is completely interactively operated. Most interlock safeties have been removed, therefore one must understand what states of operation are, and are not, allowable: specifically, the valve sequencing and operating conditions of the mass spec. Use the Veeco MS-90AB Manual as an introduction to operation, but use the specification of this write-up to actually operate the instrument.

1.1 Initial State

Front Lower-Panel Power Switches:

"Roughing Pump" Large Toggle Switch: off

"Fore Pump" Circuit Breaker: off

"Diffusion Pump" Circuit Breaker: off

"Electronics" Circuit Breaker: off

Front Lower-Panel Valve Switches:

"Rough" Small Toggle Switch: off (down)

"Fore" Small Toggle Switch: off (down)

"Test" Small Toggle Switch: off (down)

Front Upper-Panel Switches:

"Filament Off" Large Toggle Switch: Ready (up)

"Test Start/Vent" Large Toggle Switch: Not Used

Manually Controlled Valves:

Front Lower Valve ("Accumulator Valve"): Open (ccw) Front Upper Valve ("Throttle Valve"): Closed (cw)

Vent Toggle Valve (Right Hand Side of Chassis): Closed

1.2 Start-Up

Plug in Portable Leak Indicator (multi-prong socket at back)

Plug in Line Power Cord (~ 8 ft long cord stored in chassis under diffusion pump)

Turn on "Fore Pump" Circuit Breaker

Turn on "Roughing Pump" Large Toggle Switch (up)

Roughing Pump should start up

Turn on Small Toggle Switch "Fore" Valve (up)

Red LED should turn on

Wait until 'gurgling' sound stops

Close Front Lower Valve (High Vacuum "Accumulator Valve") (cw)

Turn on "Diffusion Pump" Circuit Breaker

Red indicator should turn on

Wait ~ 30 minutes until Diffusion Pump at operating temperature

Slowly Open Front Lower Valve ("Accumulator Valve") (ccw)

Crack open valve only enough to hear slight gurgling of roughing pump

When no further gurgling sound evident: open fully

Turn on "Electronics" Circuit Breaker

Yellow indicator should turn on

Add Liquid Nitrogen into Cold Trap

Press "Filament ON" Button

"Filament Off" must be in "Ready" position first

Green "Filament" indicator should turn on

Check Portable Leak Indicator:

Red "Filament On" indicator should turn on

Set to appropriate scale and properly re-zero meter

Connect chamber (or part) to the Manifold Top Port via poly tubing

Turn off Small Toggle Switch "Fore" Valve (down)

Red LED should turn off

Turn on Small Toggle Switch "Rough" Valve (up)

Green LED should turn on

Turn on Small Toggle Switch "Test" Valve (up)

Yellow LED should turn on

System under test is being rough pumped

Wait at least 3 minutes and until 'gurgling' sound stops completely

Turn off Small Toggle Switch "Rough" Valve (down)

Green LED should turn off

Wait until pump has a high pitched flutter/tapping noise

Turn on Small Toggle Switch "Fore" Valve (up)

Red LED should turn on

Slowly Open Front Upper Valve ("Throttle Valve") (ccw)

Filament will extinguish if higher pressure reached

Do the Leak Check

3.0 Shut Down

Switch "Filament Off" (toggle down)

Green indicator should turn off

Turn off Small Toggle Switch "Test" Valve (down)

Yellow LED should turn off

Close Front Upper Valve ("Throttle Valve") (cw)

Turn off "Electronics" Circuit Breaker

Yellow indicator should turn off

Close Front Lower Valve ("Accumulator Valve") (cw)

Turn off "Diffusion Pump" Circuit Breaker

Red indicator should turn off

Wait ~ 45 minutes until Diffusion Pump cooled down

Turn off Small Toggle Switch "Fore" Valve (down)

Red LED should turn off

Open Vent Toggle Valve (Right Hand Side of Chassis)

Turn on Small Toggle Switch "Rough" Valve (up)

Green LED should turn on

Turn off "Roughing Pump" Large Toggle Switch (down)

Roughing Pump should stop

Turn off "Fore Pump" Circuit Breaker

Unplug in Power Cord