EBARA A70W, Instruction Manual

Page: 16 / 69

(2)
3 Product Description
3.1 Summary
The A Series dry vacuum pump has a compact design and includes various sensors and
controls to enhance reliability and operation.
3.1.1 Pump Module
The pump is a roots-type vacuum pump that rotates a pair of non-contact, multi-stage rotors
synchronized by timing gears. High-capacity units have a Booster Pump (BP) connected in
series with the Main Pump (MP).
A compartment, isolated from the pump casing, encloses the timing gears and bearings,
which require lubrication with Perfluoro-Polyether (PFPE) oil and grease.
The pumps of this series are factory-filled with lubricating oil. Replenish or replace only with
the recommended oil grades shown in Specification Tables 3.1 and 3.2.
3.1.2 N
2
Gas
Pressurized nitrogen, supplied to the labyrinth seal section, isolates the vapor stream from
the lubricated components, enabling the pump to draw a clean vacuum without admitting
lubricant oil to the pump casing.
Additional N
2
gas, injected in various pump stages, reduces corrosion due to process gas
and retards the accumulation of reaction byproducts. For processes that do not produce
corrosion or reaction byproducts, the selector valve can stop completely the dilution N
2
flow.
Adjusting the regulation pressure to the specified value supplies the correct amount of N
2
gas for these two types of purge operation.
The pumps of this series are equipped with a dilution N
2
gas control valve. Consult EBARA
before adjusting the N
2
gas supply to the appropriate level for specific conditions of use.
(Maximum dilution N
2
flow rate: 76 Pam
3
/s.)
3.1.3 Cooling Water
Compressing gas from vacuum to atmospheric pressure generates heat. Therefore, cool
motors and casings with cooling water.
Quick-connect cooling water couplers make connection and disconnection easy.
3.1.4 Exhaust
The exhaust check valve, a standard accessory, prevents reverse flow of gas from the
exhaust back through the pump to the vacuum chamber when pump stops. A silencer
(optional) reduces exhaust noise.
3.2 Control System
A Series dry vacuum pumps have a built-in sensing unit consisting of an Earth Leakage
Breaker (ELB), an electro-magnetic switch and a control circuit or an overcurrent circuit
breaker (CB). To improve reliability and safety, sensors monitor the condition of each utility
EBARA Corporation