1.4 Safety
All of the components of the iH system are fitted inside an enclosure. Panels of the enclosure
should only be removed for access during maintenance and should at no time be removed by
the operator. Potential hazards on the iH system include electricity, hot surfaces, process
chemicals, Fomblin oil and nitrogen and water under pressure. Detailed safety information is
given in Section 3.1 (Installation), Section 6.1 (Maintenance) and BOC Edwards publication
no. P300-20-000 ‘Vacuum pump and vacuum system safety’.
1.5 The HCDP dry pump
The HCDP pump is a five-stage, positive displacement rotary pump in which pairs of
intermeshing rotors (of different profiles mounted on common shafts) are held in correct
phase relation by a pair of timing-gears. The timing-gears and the adjacent angular contact
bearings are oil lubricated.
1.6 The HCDP gas system
The HCDP pump has a gas system which is suitable for use in harsh processes, such as ion
implanters, PECVD (Plasma Enhanced Chemical Vapour Deposition), LPCVD nitride,
LPCVD TEOS and Silicides. The gas system is also suitable for use in light or medium duty
processes.
The gas system can be preset to operate in any one of the following four configurations: low
gas; medium gas; medium gas and exhaust; high gas. As supplied, the gas system is preset
for the high gas configuration. To change the gas system configuration, refer to Section 5.3.
The gas system has supply pipelines and components (such as valves), a Gas Module with a
distribution manifold, gas purge controls and sensors, and pipelines which deliver purge
nitrogen to the purge points on the HCDP pump.
The gas system provides the following purge flows to the HCDP pump:
•
Shaft-seals purge: this purge flow is on whenever the HCDP pump is on.
•
2/3-interstage purge and 3/4-interstage purge: these purge flows are either both on or both
off. The purge flows can be switched on or off by use of the Pump Display Terminal or by your
own control equipment.
•
Exhaust-purge: this purge flow is on whenever the HCDP pump is on and the gas system is
either in the high gas configuration, or in the medium gas and exhaust configuration.
•
Inlet-purge: this purge flow is only used in high gas configuration. The purge flow can be
switched on or off by use of the Pump Display Terminal or by your own control equipment.
Refer to Figure 1-2 which shows a schematic diagram of the iH gas system.
The purge flow pressure is controlled by a pressure regulator (26). A mass flow transducer
(25) measures the total flow of purge gas to the pump purge points. A check-valve (27)
prevents the flow of process gases back into your nitrogen supply pipeline.
iH Dry Pumping Systems 1-5
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