5 Function description
5.2 Functional principle
5.2 Functional principle
The pump stations of the DKC/DLC series are suitable for the parallel operation of two KRAL pumps of
the K or L series. The functional description of the pumps is contained in the associated operating in-
structions of the pumps.
This is connected with the pipe system through the suction connection
10
at the front of the station. De-
pending on the position of the reversing valve
6
, the left-hand, the right-hand or both strainers are con-
nected to the suction connection. The pumped liquid flows through the strainer from top to bottom and
thus reaches the suction connection of the attached pumps. There the pressure of the pumped liquid is
increased which finally returns to the station through the pressure connection of the pump. The
pumped liquid flows through a non-return valve in an integral duct into the lower part of the station and
via the reversing valve to the pressure connection
9
through which the fluid leaves the station again.
5.3 Reversing valve
If the lever of the reversing valve
6
is in one of the two side positions, the respectively other line of the
station is separated from the fluid circuit so that the strainer of this line can be opened and cleaned. If
the lever is in the centre position, both lines are connected to the fluid circuit. The delivery rate can thus
be increased through parallel operation of the two pumps. If only one pump is being operated, the
second pump can be cut in automatically if the delivery rate or the pressure drops at the active line. In
order to ensure a uniform distribution of the operating hours, an interval-controlled automatic switch-
over between the two pumps is also possible in this valve position. The non-return valves ensure that
the respective pump that is stopped does not begin to rotate backwards.
5.4 Expansion valve
The fluid volume in the respectively blocked line of the station could result in an impermissibly high in-
ner pressure due to heating up through thermal expansion. In order to prevent this, the cylinder of the
reversing valve contains two small spring expansion valves that vent any overpressure in the respect-
ively active line of the station.
5.5 Pressure measurement
A pressure gauge
5
is located in the centre of the station in order to monitor the delivery pressure. The
pressure gauge is always connected to the pressure side of the station and is thus independent of the
position of the reversing valve
6
. In order to monitor the pressure on the suction sides of the two
pumps, two further pressure gauges
3
are mounted. These pressure gauges show only the respective
pressure at one of the two strainers and can be used to monitor the degree of soiling of the strainers.
The pressure gauge in the blocked line shows only the inner pressure of the blocked strainer. The
stopcocks at the pressure gauges may only be opened to read the pressure values,
Operating instructions
OID 02en-GB Edition 2019-11
13
