Daikin REYQ96MTJU, Инструкция по проектированию, установке и испытаниям, Страница: 42 / 236

Installation Si39-406
36 General Information
1. Vacuum pump performance
The 2 most import things for determining vacuum pump performance are as follows:
(1) Exhaust velocity
(2) Degree of vacuum
(1) Exhaust velocity
Exhaust volume is usually expressed as l/min or m³/h. The larger the number, the faster vacuum
id achieved.
Generally speaking, the faster the exhaust velocity, the larger and heavier the vacuum pump
itself is.
Commercially available vacuum pumps (exhaust velocity of 20 - 30 l/min) usually take an
extremely long time to achieve vacuum. (We recommend a vacuum pump of approx. 60 - 100 l/
min.)
(2) Degree of vacuum
Ultimate vacuum varies largely according to use of the vacuum pump. Vacuum pumps used for
vacuum forming cannot be used for vacuum drying. (A vacuum pump with a high degree of
vacuum is required.)
When selecting a vacuum, you should select one which is capable of achieving 0.2 Torr of
ultimate vacuum.
Degree of vacuum is expressed in Torr, micron, mmHg, and Pascal (Pa). The units correlate as
follows:
2. Vacuum pump maintenance
Because of their nature, most vacuum pumps contain large amounts of oil which lubricates
bearings, etc., and functions to enhance airtightness of pistons. When using a vacuum pump to
discharge air from refrigerant piping, moisture in the air tends to get mixed in with the oil. You must
therefore change oil periodically and make sure the proper oil level is maintained. (Perform periodic
inspections in accordance with the operating instructions.)
Unit Standard atmospheric pressure Perfect vacuum
Gauge Pressure kg/cm
2
0 –1.033
Absolute Pressure kg/cm
2
abs 1.033 0
Torr Torr 760 0
Micron Micron 760000 0
∗
mmHg mmHg 0 760
Pa hPa 1013.33 0
psi psi 0 –14.7
Degree of vacuum must be within the range expressed by
0 Torr
0 Pa
760 mmHg
–14.7 psi
Perfect vacuum
5 Torr
667 Pa
755 mmHg
–14.6 psi
Vacuum target value
760 Torr
1013.33 hPa
0 mmHg
0 psi
Standard atmospheric pressure
(V0992)