Speck pumpen VZ 11 B Series, Руководство по эксплуатации

Страница: 25 / 48

OPERATING INSTRUCTIONS
25
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. 3-5
times the volume of circulation liquid indicated
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
condensation before the vacuum pump is
preferrable (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, however cavitation will
be prevented. The regulating valve has to be
locked 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 suc-
tion 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 1. For that, the temperature difference
∆
t (temperature of operating water minus
temperature of fresh water) has to be stipu-
lated. In case that the operating temperature is
too high and the vacuum is accordingly, cavita-
tion will occur.
For closed circulation cooling the flux of
circulating liquid corresponds to the flux of
fresh liquid at continuous cooling. The liquid
level has to be checked and possibly regulated
from time to time at the liquid indicator.
When the vacuum-pump is idle, the process
liquid level may not be higher than the middle
of the shaft.
Diagr.1a: Fresh water requirement VZ 110-180
Fr
es
h
w
at
er
re
qu
ire
m
en
t
C
on
tin
uo
us
c
oo
lin
g
[m
3
/h
]
Suction pressure [mbar] Fresh water requirement
open circulation cooling [m³/h]