Description; How The Nash Vacuum Pump Works - BeaconMedaes Lifeline Camel Installation, Operation And Maintenance Manual

"Camel" Liquid Ring Medical Vacuum
B.2

Description

This bulletin contains information for owners and operators of Nash MHF 50, MHF 80, and MHF 120 vacuum
pumps. This information includes a description of how to operate and maintain these vacuum pumps.
B.2.1

How the Nash vacuum pump works

The main functional assemblies of a Nash vacuum
pump are shown in Figure 1-1. A motor that is directly
coupled turns a rotor (8) in the vacuum pump to the
drive shaft (9). MHF pumps are assembled to the
electric motor shaft. The rotor (8) lies within a chamber
formed by the casing of the lobe (2).
Liquid compressant (usually water), which is called the
seal liquid, is applied to the chamber from a liquid inlet
(5, Figure 1-1) through the head (3). Figure 1-2 shows
the functional operation of the vacuum pump. The
actions illustrated therein and described below are made
possible because the axis of the lobe (2, Figure 1-2)
casting is offset from the axis of the rotor (3) and the
head.
a. Inlet liquid compressant fills the rotor sector at point
A, Figure 1-2.
b. Centrifugal force empties the sector at point B1,
forcing the liquid compressant towards the lobe (2)
casing. Low pressure at point B2, caused by the
receding of the liquid compressant from the center of
the rotor (3) chamber, draws air through the head air
inlet port (5).
c. Air is compressed by converging the liquid
compressant at point Cl. The liquid compressant is
forced back toward the center of the rotor (3) chamber
at point C2.
d. The liquid compressant and compressed air are
discharged at point D.
The motion of the liquid being rotated in the pump operates as a compressant for the air pump. In addition, the
liquid compressant acts as a seal, preventing air leakage to the atmosphere.
1. Drive Shaft
2. Lobe
3. Rotor
4. Head Discharge Port
Fig 1-2 Functional Operation of Vacuum Pump
B-3
1. Test Number
2. Lobe
3. Head
4. Air Air Inlet
5. Liquid Compressant inlet
6. Air Discharge
7. Drain Plug
8. Rotor
9. Drive Shaft (Motor or Pedestal Assembly}
Figure 1-1. Functional Assemblies of Vacuum Pump
5. Head Inlet Port
Medical Systems