NA
Y
AC
2
'
•
Warning
Before starting the pump, the motor must be effectively grounded and properly connected with a rated motor protection switch.
'
•
Warning
The pump is strictly prohibited to pump dusty, active toxic, corrosive, flammable and explosive gases.
!
Warning
Do not place obstacles which may affect the ventilation of the motor to avoid burn hazard and fire caused by abnormal temperature
rise.
!
Warning
The exhaust passage must be unimpeded during operation. Make sure that the gas flow from the exhaust port is not blocked
or restricted in any way.
f
Notice
•
The pump must be operated at ambient temperature between 10 - 40
'C.
'
•
Notice
Check the oil level before running. Do not operate the pump without oil or short of oil. Otherwise it will result in pump failure.
'
•
Notice
Check oil leakage of the pump to prevent slip hazard caused by spilled oil.
'
•
Notice
Running without oil lubrication or wrong rotation direction of the motor may cause pump failure.
'
•
Notice
Do not connect the intake port with an overpressure device. Make sure the size of the exhaust passage with absolute pressure
is not more than 1.35 bar (relative pressure is not more than 0.35 bar).
f
Notice
•
Handling of used oil and other parts must be in compliance with local relevant environmental laws and regulations.
f
Notice
•
To pump condensable gases, only use the pump installed with gas ballast.
f
Notice
•
While pumping a small amount of dust and condensable gases, an installation of corresponding filters is required. Otherwise
it will cause pump failure or sharp drop of performance.
3. Description
NRD series vacuum pump is a high speed, motor direct drive dual-stage oil sealed rotary vane pump. It is an basic equipment to
obtain vacuum and can be used to pump inactive gas within the scope of low vacuum and a small amount of non-condensable gas.
The pump is specially suitable for coating, refrigeration, freeze drying, sterilization, instruments analysis, leak detection equipment,
heat treatment metallurgy, etc. It can be used as a backing pump for roots pumps as well.
The pump has a reasonable structure design (Refer to Fig. 1) for long failure-free operation. It features high reliability, high flow rate,
low ultimate pressure and low noise level. The pump has no oil spray, no leak and easy to maintain.
9.
10.
11
Fig. 1 Outside view
3.1 Principle of Operation
1. Outlet
2. Junction box cover
3. Junction box
4. Intake port
5. Gas ballast
6. Exhaust port
7. Oil fill plug
8. Oil housing assy
9. Sight glass
10. Oil drain plug
11. Pump feet
12.Support
13. Motor
Pump
cylinder
Vane
Rotor
Fig. 2 Functional diagram
Refer to Fig. 2, the rotor mounted eccentrically in the pump cylinder, has two vanes which divide the pump chamber into three
changeable compartments. When the rotor rotates clockwise, gas is sucked into chamber 1 gradually, transferred by chamber 2,
and compressed and exhausted by chamber 3. The working cycle is repeated to achieve the vacuum of the system. The exhausted
gas from the first stage goes into the second stage (low-vacuum stage) through air channel, and is compressed again before
discharging into atmosphere to achieve a lower ultimate vacuum pressure .
3.2 Principle of Gas Ballast
The controllable gas (generally dry air at room temperature) is admitted into the pump chamber. It is mixed with pumped vapor during
the gas compression process .
This increases the percentage of non-condensable gas such that the partial pressure of the vapor being pumped is below its saturated
vapor pressure when the exhaust valve opens. The vapor is then discharged from the pump without liquefaction. The more vapor
contained in the pumped gas, the more dry air is required (See Fig. 7 Gas ballast valve).
3
