OPERATING INSTRUCTIONS
24
7
Operation
7.1
General
When delivering air and other inert gases
normally water is used as ring liquid. Other ring
liquids than water may also be used in order to
meet with the requirements to the kinds of
gases and separators chosen. The ring liquid
has to be free from foreign bodies, as other-
wise the casing will be worne out. Use appro-
priate filters to keep the pump free from con-
taminants.
During operating temperature, the kinematic
viscosity should be at max. 4 mm
2
/s; higher
viscosity requires higher performance of drive.
The steam pressure of the ring liquid should be
at 16 mbar during vacuum operation at work-
ing temperature; higher steam pressures
reduce the suction capacity and final vacuum
indicated in the performance tables resp.
characteristic curves. In case other ring liquids
than water will be used, the performance data
of the pump should be confirmed by us.
When delivering other liquids as well (ca.
2 times the volume of circulation liquid indi-
cated in the brochure) the supply of clean
liquid can be reduced considerably.
A condensation of steam in the vacuum pump
may cause cavitation and consequently de-
stroy parts of the pump. Therefore a conden-
sation before the vacuum pump is preferable
(injection condensor, surface condensor etc.)
In some cases the condensate arising can also
be delivered by the vacuum pump. Otherwise
a separate liquid ring pump has to be provided.
The specification should be stipulated by the
manufacturer/supplier.
The suction capacity listed (resp. the flux
volume listed) is reached by an operating
temperature of 15 °C. An operation at higher
temperatures of operating liquid will cause a
reduced suction capacity (resp. a reduced
volume flow), however, gives the possibility of
safing fresh water resp. cooling liquid at open
resp. closed circulation cooling. Such liquid
quantity should be regulated by the regulating
valve
r
F
resp.
r
B
only as high as the required
suction capacity (resp. the required volume
flow) will be reached. The regulating valve has
to be blocked at this position.
For vacuum operation with suction pressures
below 130 mbar it should also be taken care
that the operating water temperature should
not be below ca. 10 °C, as otherwise the
suction nozzle gets covered with ice.
7.2
Fresh water requirement
For continuous cooling a fresh water quantity
according to
diagram 1
is necessary.
The fresh water requirement for open circula-
tion cooling will be made up according to
diagram 1a and 1b
. For that, the temperature
difference
Δ
t
(temperature of operating water
minus temperature of fresh water) has to be
stipulated. In case that the operating tempera-
ture is too high and the vacuum is accordingly,
cavitation will occur.
For operation with other speed rates as indi-
cated, the fresh water requirement has to be
converted proportionally to the change of
speed rate.
For closed circulation cooling the flux of
circulating liquid corresponds to the flux of
fresh liquid at continuous cooling.