Bibby Scientific Stuart RE3011C Instructions De Service page 8

Description
3 Description
3.1 Design
The diaphragm pump consists of a pump
casing and a drive motor.
The pump casing contains the drive unit and
two pump heads.
Both pump head contains a diaphragm and
the work valves. Two pair of pump heads are
arranged opposite each other.
The pump heads are driven via an eccentric
shaft with a connecting rod.
3.2 Principle of Operation
Motor, eccentric shaft and connecting rod set the diaphragms in stroke movement. This
changes the size of the space between the diaphragms and pump head (pump chamber).
Increasing the size of the pump chamber opens the inlet valve while the outlet valve is
closed (intake process).
Decreasing the size of the pump chamber ejects the gas through the outlet valve.
The valves are actuated by the gas being pumped. A large proportion of fluid in the dia-
phragm pump minimizes the pumping efficiency.
3.3 Gas ballast
When condensable vapours are pumped, they
may be compressed above the saturated vapour
pressure and condense.
Opening the gas ballast valve (A) in the suction
line of the last pump stage allows air to flow into
the pump chamber. This prevents condensation
and flushes the pump clear.
Operation leads to increasing the ultimate pres-
sure and the operating temperature.
8
Fig. 1 Diaphragm pump RE3011C
(A)
Fig. 2 Gas ballast valve
RE3011C