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5.Specification
5.1 Ultimate pressure
The 「Ultimate Pressure」described in the catalog or this manual means
obtainable minimum pressure by vacuum pumping at inlet port without conducting
gas (no load operating). Our ULVAC KIKO,Inc. applies the specified pump oil and
measures the pressure at inlet port attached the sensor of only the PIRANI gauge.
In actual vacuum system, the ultimate pressure reading will be higher than the
catalog description. This reason will be shown as follows.
① When the vacuum sensing head location is far from the pump, any water vapor
or gas, generated from any water droplet or any rust adhered to the inside
surface of the vacuum vessel or the vacuum tubing may cause high ultimate
pressure.
② Any volatile contents dissolved into the pump oil will vaporize and it may
cause higher ultimate pressure.
③ If there is any leakage or gas source in the vacuum tubing, the ultimate
pressure will be high.
5.2 Pumping speed
Pumping speed of the oil rotary pump must be changed with sort of gases. Generally,
pumping speed will be max in high-pressure range, and will be proportional to
vacuum pressure reduction. The standard pumping speed of this pump shows the
maximum speed when pumping dry air. Inlet pressure Vs pumping speed is shown
in Fig-6.
5.3 Required electricity
Driving power for motor is totaled mechanical work based on rotor friction and
air compression work. It will be maximum at 4×10
４
～2.7 ×10
４
Pa. At lower
pressure than 13.3Pa, compression work is small and almost power will be
mechanical work consumption. Fig-7 shows minimum power required operating the
pump.
