English (GB)
15
4.1.2 Start and stop levels for dry installation
Stop levels
The stop level setting for dry-installed pumps depends on the
inlet pipe height, shape and flow velocity. Set the stop level
approx. one inlet pipe diameter above the inlet pipe. The final
stop level must be confirmed through test runs during startup.
Start levels
In pits with dry-installed pumps, set the starting level above the
pump housing in order to ensure that the cooling jacket is filled up
before the pump starts pumping. For vertical pumps, this height
may be considerable and should be set with a margin according
to fig.
.
Fig. 18
Vertical, dry installation (D)
Horizontal pumps do not normally require special considerations
for the start level if the inlet pipe is designed to prevent air
pockets from forming. See fig.
Fig. 19
Horizontal, dry installation (H)
S
is the minimum stop level. The minimum distance S above the
inlet pipe is required to avoid the formation of vortices at the inlet
pipe and thus to avoid air being sucked into the pump. Air in the
pumped liquid may cause vibrations, cavitation and loss of pump
performance.
G
is the minimum start level of a dry-installed, vertical pump if no
other actions are taken to ensure that the pump housing is filled
with pumped liquid when the pump is started.
Other possible actions:
• Use a vacuum pump to suck liquid into the pump housing; this
requires an isolating valve on the outlet side.
• Install a non-return valve in the outlet pipe after the first
startup; this will prevent the draining of the pump housing
between running periods.
4.2 Checking the direction of rotation
A label with an arrow on the pump housing indicates the correct
direction of rotation. The direction of rotation is clockwise when
seen from the drive end.
Installation types S, C and ST
Proceed as follows:
1. Lift the pump approx. 2-5 cm from the ground or base using
the lifting chain and a crane.
2. Start and run the pump for a few seconds.
3. Observe the jerk of the pump. If the pump jerks counter-
clockwise, the direction of rotation is correct.
In case the direction of rotation is wrong, interchange two phases
in the power supply cable.
Installation types D and H
Check the duty point.
TM
0
5
8
1
87
2
013
T
M
04
69
01
1
11
0
Minimum stop level
S = D
1
Minimum distance between
bottom of pit and lowest part of
inlet pipe
F = 0.5 x
D
1
Minimum start level
G = D
p
G
S
D
F
D
p
1
Reductio
n elbow
Eccentric
Only start and run an
unsubmerged pump for a few
seconds to check the direction of
rotation.
DANGER
Crushing of hands
Death or serious personal injury
- Do not touch the pump when
starting it up.
Make sure that the bottom of the
pit is clean before startup to avoid
material or objects being sucked
into the impeller.
