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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.
Pirani gauge indicates 5～10 times higher pressure reading than by the McLeod gauge. This means
condensable contents (almost water vapor), included in the gas, could not be measured by the
McLeod 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-7.
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-8 shows minimum power
required operating the pump.
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