Oxford Instruments OpAL, System Manual

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All OIPT Systems Oxford Instruments Plasma Technology
System Manual
Rotameter Data
Issue 2: October 04 Page R 2 of 6
Printed: 5-Jun-09, 9:58
1 Rotameters
A rotameter is a manually controlled variable valve/indicating tube, used by OIPT to manually set the
flow rate
1
for various gas supplies. For example, purge flow rates for turbomolecular
2
, rotary vane
and dry pumps, glove boxes and etch gas supplies for process chamber cleaning.
Flow control
knob
Graduated
scale
Ball float
Tube type number
is marked on this
side of the tube
Fig 1: Typical rotameter
1.1 Rotameter types
The models of rotameter used for setting purge gas flows on OIPT equipment is fitted with a

The tube type (marked on the tube itself)
ws given in the following table are for 20° C, 1 atmosphere pressure, air or nitrogen
common scale, reading from 0 to 6 as flow is varied from zero to full scale. The full-scale flow
depends on:
 The ball material

The gas type

Temperature

Pressure
The full-scale flo
as. g
OIPT part Tube number Ball material Normal use Full scale flow
G/GAS/ROT/05 A125-3 Glass Turbo pump purge 53 sccm
0
G/G 5L C Rotary pump purge, PECVD 2 AS/ROT/2 A250-4 arboloy 7.5 slpm
G/GAS/ROT/40L A250-6 Stainless steel Pump exhaust purge 43.4 slpm
G/GAS/ROT/80
0
A125-7 Stainless steel etering CF4/O2 ‘clean gas’ m 850 sccm
G/GAS/ROT/90
0
A250-1 Stainless steel Rotary pump purge, etch,
PECVD
4.4 slpm
1
Flow rates are quoted in either standard cubic centimetres per minute (sccm) or standard litres per minute (slpm).
2
In most OIPT systems, turbomolecular pump purge flows are set automatically and monitored by the system software via a
flow meter: these systems do not incorporate a rotameter for the turbo pump purge.