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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-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.
