Before starting, centrifugal pump (except self-priming pump) shall fill the
water pump and water inlet pipe with water, otherwise the pump will not be able
to lift water. After the centrifugal pump is started, it is often caused by the
air in the pump not being drained and the water is not filled.
There are two
main methods for water filling before start-up: one is to install the bottom
valve to fill water, the bottom valve is a one-way valve, and installed at the
inlet of the water inlet. The disadvantage of this method is that the head loss
of the bottom valve is large, which affects the efficiency of the pump; the
other is the filling of water without the bottom valve. The biggest advantage of
this method is energy saving, which can save 10% - 15% compared with the pump
station with bottom valve. The following introduces several methods of water
filling for centrifugal pumps, which can be selected by users when running the
pumps.
■ self diversion and water filling method: for pump house with semi
submerged type (i.e. pump station with inlet pipe and pump top elevation below
the water surface of intake pool), water can be introduced into the water pump
by itself without manual water filling. The disadvantage of this pump station is
that the water absorption capacity of the pump is not fully utilized, and the
installation elevation of the pump is reduced, which not only increases the
excavation quantity of the foundation, but also inconveniences the operation and
management; but the advantages are obvious, that is, it is easy to realize the
automation of the pump station and has strong timeliness.
■ manual water
filling: for small pump stations with inlet pipe diameter less than 300mm,
bottom valve is usually set at the inlet of water inlet, and manual water
filling method is generally adopted, that is, from the special water filling
vent at the upper part of the pump shell, water is filled by water filling
funnel (or a common bottle with inverted bottle removed from the bottom of the
bottle). For small pump stations with inlet pipe diameter less than 300mm, there
is usually a bottom valve at the inlet of the inlet pipe, and water can be
filled into the pump from the outlet of the pump (pump station with short outlet
pipe). Because there is no need to buy other water filling equipment, this
method is more common in small pumping stations in rural areas.
For small
pump stations without bottom valve and check valve and short pipeline, the
method of starting at one side and filling water into the pump from the outlet
of water pipe can be adopted, so as to gradually bring out the air in the pump
and pipeline. Generally, after several minutes of continuous water filling, the
pump can pump normally.
■ vacuum water tank filling method: for small pump
stations without bottom valve, the vacuum water tank filling method can be used.
Vacuum water tank is a closed water tank welded with iron sheet, with a volume
of at least 3 times of the volume of the water inlet pipe. The water tank shall
be installed as close to the water pump as possible, and the bottom height of
the water tank shall be slightly lower than the axis of the pump. The height of
vacuum tank is generally twice the diameter of the tank.
Before the pump
starts, fill the water tank with water for sealing. After the pump is started,
the water pump enters the water from the vacuum tank. Due to the water level
drop of the water tank, a certain vacuum will be formed in the water tank. The
water in the water tank will enter the water tank through the water inlet pipe
under the action of atmospheric pressure, thus forming the water circulation and
making the pump start to operate normally.
■ water filling method of jet
pump: when the diesel engine is used to drive the pump to pump water, the
exhaust gas discharged by the diesel engine can be used to connect with the jet
device connected with the top of the pump to pump the air and fill water, thus
removing the bottom valve of the pump. When the pump is started, the valve cover
connected with the handle is closed, and the exhaust gas is ejected from the
jet, and the air in the pump is sucked out through the coupling pipe. After
filling water, open the valve cover and close the control valve. The advantages
of this method are: the full use of the power machine, and the improvement of
the efficiency of the pump station.
■ self suspension water filling method:
self suspension diversion and water filling method is realized by using the
principle of "water gas replacement" by using the unit weight difference between
water and gas. The bottom valve of the water pump can be removed by this
method.
First, a suitable amount of container is designed. The air exchange
tank is generally plastic products, but also can be thin iron sheet, with the
cost only one-half of the bottom valve. Then, the air exchange tank is arranged
at the water inlet of the water pump, forming a connecting body with the water
pump and pipeline. At the same time, a control valve for air exchange is
installed on the air exchange channel between the air exchange tank and the
water pump. When filling water, fill the air exchange tank with water in
advance, then seal it, and then open the air exchange valve. After the air
exchange is completed, close the air exchange valve and suspend a part of the
water diversion in the water inlet pipe. Repeat this method several times, the
air will be drained out, and the water inlet pipe will be filled with water. At
this time, the pump can be started for water lifting. Before the shutdown, as
long as the gate valve is closed before the shutdown, the water diversion will
not sit back. The next time you start, you don't have to refill the water. The
advantages of this method are low price of air exchange tank, easy manufacture,
low labor intensity and energy saving.
■ vacuum pump water filling method:
for large and medium pump stations with inlet pipe diameter greater than 300mm
or pump stations with high automation requirements, vacuum pumping device is a
common water filling equipment. It is made up of vacuum pump and other
equipment. Most of the vacuum pumps used in drainage and irrigation station are
water ring vacuum pumps.
An eccentric tooth impeller is installed in the
cylindrical pump shell of the water ring vacuum pump. Circulating water is
injected into the pump shell. When vacuum is being pumped, the impeller rotates.
Under the action of centrifugal force, the circulating water in the pump shell
is dumped around the impeller, forming a rotating water ring on the inner wall
of the pump shell. Because the impeller is installed in the pump shell
eccentric, the space between the water ring and the tooth blade is different.
When the impeller is rotated clockwise, the air between the two blades in the
right half The pressure decreases with the increase of air volume under the
closed condition. The air in the pump and the pipeline enters the crescent
shaped suction port on the right side of the pump shell and is drawn into the
vacuum pump. The space between the left half of the impeller of the vacuum pump
is gradually reduced, so the air is compressed and the pressure increases.
Finally, the air is compressed and the pressure increases. Finally, the pressure
is increased by the air suction pipe The crescent exhaust port on the left side
of the vacuum pump shell is discharged from the vacuum pump and enters the water
and gas separation tank to separate the circulating water taken out before
reuse. The impeller is rotating constantly, and the vacuum pump constantly
inhales and exhausts, and finally fills the pump with water.
Manual pump
water filling method: as a reciprocating positive displacement pump, manual pump
is widely used in rural areas of China. Farmers can use their own manual pump as
vacuum pump to fill water for centrifugal pump, which is convenient and
economical. The most common usage is: the manual pump is installed on the
suction hole of the centrifugal pump or on the water inlet pipe near the pump to
pump for air pumping and water diversion, making it a tool for filling water
when the centrifugal pump is started, thus saving the bottom valve on the water
inlet pipe of the pump, reducing the energy loss and improving the efficiency of
the pump device.
■ self diversion and water filling method: for pump house
with semi submerged type (i.e. pump station with inlet pipe and pump top
elevation below the water surface of intake pool), water can be introduced into
the water pump by itself without manual water filling. The disadvantage of this
pump station is that the water absorption capacity of the pump is not fully
utilized, and the installation elevation of the pump is reduced, which not only
increases the excavation quantity of the foundation, but also inconveniences the
operation and management; but the advantages are obvious, that is, it is easy to
realize the automation of the pump station and has strong timeliness.
■ self
suspension water filling method: self suspension diversion and water filling
method is realized by using the principle of "water gas replacement" by using
the unit weight difference between water and gas. The bottom valve of the water
pump can be removed by this method.
First, a suitable amount of container is
designed. The air exchange tank is generally plastic products, but also can be
thin iron sheet, with the cost only one-half of the bottom valve. Then, the air
exchange tank is arranged at the water inlet of the water pump, forming a
connecting body with the water pump and pipeline. At the same time, a control
valve for air exchange is installed on the air exchange channel between the air
exchange tank and the water pump. When filling water, fill the air exchange tank
with water in advance, then seal it, and then open the air exchange valve. After
the air exchange is completed, close the air exchange valve and suspend a part
of the water diversion in the water inlet pipe. Repeat this method several
times, the air will be drained out, and the water inlet pipe will be filled with
water. At this time, the pump can be started for water lifting. Before the
shutdown, as long as the gate valve is closed before the shutdown, the water
diversion will not sit back. The next time you start, you don't have to refill
the water. The advantages of this method are low price of air exchange tank,
easy manufacture, low labor intensity and energy saving.
■ vacuum pump water
filling method: for large and medium pump stations with inlet pipe diameter
greater than 300mm or pump stations with high automation requirements, vacuum
pumping device is a common water filling equipment. It is made up of vacuum pump
and other equipment. Most of the vacuum pumps used in drainage and irrigation
station are water ring vacuum pumps. An eccentric tooth impeller is installed in
the cylindrical pump shell of the water ring vacuum pump. Circulating water is
injected into the pump shell. When vacuum is being pumped, the impeller rotates.
Under the action of centrifugal force, the circulating water in the pump shell
is dumped around the impeller, forming a rotating water ring on the inner wall
of the pump shell. Because the impeller is installed in the pump shell
eccentric, the space between the water ring and the tooth blade is
different.
When the impeller rotates clockwise, the space between the two
blades in the right half increases gradually. Under the closed condition, with
the increase of air volume, the pressure decreases, forming a vacuum. The air in
the pump and the pipeline passes through the suction pipe, and enters the
crescent shaped suction port on the right side of the pump shell to be drawn
into the vacuum pump. The space between the left half of the impeller and the
two blades of the vacuum pump impeller is gradually increasing The air is
compressed and the pressure increases accordingly. Finally, the vacuum pump is
discharged through the crescent shaped exhaust port on the left side of the pump
shell of the vacuum pump, and then enters the water and gas separation tank, so
that the circulating water taken out is separated and reused. The impeller is
rotating constantly, and the vacuum pump constantly inhales and exhausts, and
finally fills the pump with water.
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