Specifications and Installation
1-3
Table 1-2. VHS-400 Pump Specifications
(Cont'd)
Pressure drop across coils
6 psi
Backing Pump Size Recommended
30 cfm for maximum throughput
Jet Assembly
4-stage, self-aligning, aluminum
Foreline Baffle
Stacked, self-aligning half moon
Cold Cap
Nickel-plated Copper
Water Connections
1
⁄
8
FPT
Thermal Switches
Manual reset at 300°F
Heater circuit resistance (ohms)
4400 watts
____________________
L1-L2
L2-L3
L1-L3
208V
19.6
19.6
39.2
240V
26.2
26.2
52.4
380V
65.6
65.6
131.2
480V
104.7
104.7
209.4
____________________
Clearance (for heater removal)
6 inches minimum
Materials
Body – Stainless steel
Flanges, foreline baffle – Mild steel
Jet Assembly – Aluminum
Body Cooling Coils – Copper
Quick Cooling Coil – Stainless steel
Cold cap – Nickel-plated copper
Shipping Weight
180 pounds
1-2
INSTALLATION
1-2-1 Unpacking
a
Inspect the pump to ensure that no damage has occurred during shipping. Do not discard any
evidence of rough handling; any damage should be reported to the carrier and to Varian
without delay.
b
Diffusion pumps are factory-packed to permit prolonged storage in suitably protected areas
without special precautions.
c
Remove flange covers and protective plugs from water connections. Be careful not to scratch
the O-ring seal surface on the inlet and foreline flanges.
d
Inspect the internal jet assembly. It should be concentric and firmly seated on the bottom of the
diffusion pump. Using a flashlight, check to ensure that the ejector nozzle is directly in line with
the foreline. The location of the jet is controlled by an indexing pin located on the bottom of the
pump.
e
The pump requires no initial cleaning if the required vacuum level is above 10
-6
Torr (.000133 Pa).
For pressure below 10
-6
Torr (.000133 Pa), follow the cleaning procedure in the Maintenance
section. Then charge the pump with the diffusion pump oil shipped with the pump.
