Edwards RV12, Инструкция по эксплуатации, Страница: 11 / 64

oil
‑
sealed, sliding
‑
vane vacuum pumps. The pump has NW25 inlet (4) and outlet (7)
ports, a gas
‑
ballast control (5) and a mode selector (11). When the pump is switched off,
an inlet
‑
valve seals the inlet and prevents the suck
‑
back of air and oil into the vacuum
system.
The RV3 and RV5 pumps have a retractable lifting handle (3). The RV8 and the RV12
pumps are fitted with a lifting bracket for use with suitable lifting equipment.
An oil
‑
pump delivers pressurised oil to the vacuum pumping mechanism in the RV
pump. The oil level and condition can be inspected in the oil
‑
box through a sight
‑
glass
(8). Two oil filler
‑
plugs (6) and an oil drain
‑
plug (9) are provided on the oil
‑
box.
The pump mechanism is driven directly by a single
‑
phase or three
‑
phase electric motor
through a flexible motor
‑
coupling. The motor is totally enclosed and is cooled by the
motor cooling
‑
fan which directs air along the motor fins. The pumps are cooled by an
additional fan attached to the motor
‑
coupling.
Single
‑
phase motors are fitted with an on/off switch (12) and a thermal overload device.
When the motor is too hot, the thermal overload device switches off the pump. The
thermal overload device has an automatic reset; when the motor cools down, the device
resets and (unless suitable control equipment has been incorporated which must be
manually reset: see Connect the pump to the electrical supply on page 28 and Connect
the pump to the local electrical supply on page 30), the motor will restart.
As of the end of 2009 improved motors have been fitted to RV pumps. These motors
benefit from being fitted with an aluminium terminal box and externally accessible
voltage change
‑
over switches. The introduction of these motors has resulted in the
range of motors covering all voltage and frequency conditions being reduced from four
variants to two. All motors are interchangeable and pump performance is not affected.
The pump is mounted on a base plate on rubber feet (10). Details of suitable vibration
isolators and other accessories are provided in Service and spares on page 50.
Refer to PFPE
‑
prepared RV pumps refer to PFPE-prepared RV pumps on page 56 for
additional information if the pump is PFPE
‑
prepared.
2.4 Performance modes and controls
The pump has two controls: the mode selector (11) and the gas
‑
ballast control (5). Six
possible combinations of these controls allow for a wide choice of operating
characteristics to optimise the performance of the pump for a given application.
2.4.1 Mode selector
The mode selector has two positions, refer to How to use the pump controls on page 35
to select these positions. Throughout the rest of this manual, the following convention is
used:
▪ The High Vacuum mode is specified by the
S
symbol.
▪ The High Throughput mode is specified by the
S
symbol.
With the mode selector set to High Vacuum mode
S
, pressurised oil is fed to the low
vacuum stage only. In this mode of operation, the pump provides the best possible
ultimate vacuum.
03/2021 - ©Edwards Limited Page 11 A65201880_AA
A65201880_AA - Introduction