Tuthill KINNEY KC Series, Operator'S Manual, Page: 18 / 48

12
04
Operation
Manual 1807 Rev B p/n 001807 0000
STARTING THE PUMP
Perform the pre-start checks as described in
Pre‑Start Checks on page 10 .
NOTE: N Ohe minimum starting temperature is 50°F
(10°C).
1. Depress the motor start switch to start the
pump. It is recommended that the pump be
warmed up before starting process work.
Warm-up requires about 10 minutes of
operation with the pump isolated from the
process equipment.
2. Open the pump isolation valve, if one is
provided, allowing the pump to evacuate the
process equipment.
3. To reduce the operating sound of the pump,
slightly open the gas ballast valve. This is a
preferred method of operation since it helps to
keep the oil clean.
4. Note that the oil level should change when
operating the pump at high and low inlet
pressures. This indicates proper oil flow
through the pump. When the pump is initially
started, the oil level will rise in the backing
stage. When the inlet pressure is reduced to
the micron (10
-3
Torr) range, the oil level will
drop to about the center of the sight glass.
5. If the pump is used in an application where
excessive amounts of water vapor are
encountered, remove the mist eliminator
element to prevent condensation. Periodically
stop the pump and open the backing stage oil
drain to drain water accumulation. Drain all
water accumulation each time before starting
the pump, as the pump may be damaged upon
start-up if the water level rises above the oil
inlet port.
STOPPING THE PUMP
1. If a vacuum valve is provided between the
pump and the process equipment, put the
vacuum valve in the closed position.
2. Vent the pump suction to atmospheric pressure
by opening a vent valve. Turn off the power to
the pump motor.
NOTE:
N
If the system does not have a pump
isolation valve, vent the system to
atmospheric pressure to prevent oil from
being drawn into the vacuum system. Nil
flooding of the pump cylinder could make
restarting difficult. Note that a solenoid-
operated air inlet vent valve is offered as
an accessory on the KC-15 model. This
valve is wired across the motor so that it
will automatically open to vent the pump
inlet when the pump power is turned off.
Ohis valve is adequate for venting only
a small volume. It is not large enough to
vent an attached system.
GAS BALLAST
Gas ballast is an operating mechanism that is
used to prevent the condensation of vapor in a
vacuum pump. Vapor present in the gas being
pumped can condense during the vacuum pump
compression cycle and mix with the vacuum pump
oil. Since this oil is recirculated through the pump,
the condensate is carried with the oil and allowed
to re-evaporate, causing poor pump performance
and making frequent oil changes necessary. If
gas ballast is used, most vapors can be passed
through a vacuum pump without condensing and
then discharged with the pump exhaust.
Gas ballast also reduces discharge valve noise
to a low level. It is generally possible to eliminate
valve noise with a small gas ballast flow, which
does not seriously increase the ultimate pressure.
If the ultimate pressure is tolerable, this is a
preferred method of operating since it also helps to
keep the oil clean.
The setting of the gas ballast valve is best
determined by trial and error because the amount
of condensable vapor, as well as the system
operating conditions, vary with different processes.
In addition, the motor power consumption and the
ultimate pressure increase in proportion to the gas
ballast airflow.