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Basics of HydroSelf flushing system in rectangulartanks, round tanks and tunnel sewers Dipl.-Ing. Joerg
Steinhardt Dipl.-Ing. Bernhard Hommer September2006

HydroSelf£
flushing system

Basics of wave flusher inrectangular tanks
round tanks andtunnel sewers

Dipl.-Ing. Jörg Steinhardt
Dipl.-Ing. Bernhard Hommer
September 2006

HydroSelf® flushing system in Singapore

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Basics of HydroSelf flushing system in rectangular tanks, round tanks and tunnel sewers Dipl.-Ing. Joerg Steinhardt Dipl.-Ing.
Bernhard Hommer September 2006

Basics of HydroSelf£ flushing system inrectangular tanks,round tanks andtunnel sewers
1. Introduction
The HydroSelf flushing system was developed by Steinhardt GmbH and put on themarket for the first time in 1985 as a novel flushing system with flushing gates. Whatwas special about the flushing gates was the hook closure, which could be locked
and unlocked exclusively via mechanical forces (water power) by means of anencased hydraulic cylinder. The electric control for larger tanks was included at alater point in time.
In Germany, in Europe and worldwide more than 1000 facilities, stormwater tanks,
reservoir channels and transport collectors have been equipped with the HydroSelf
flushing system.
The success of the HydroSelf
flushing system for tanks andchannels is based on the abrupt
opening of the flushing gate, whichcauses a flushing wave, similar to adam break. The flushing waterretained in the storage chambers by
the flushing gates flows out rapidly
and moves with enormous thrustforce over the soles of thestormwater tanks and channels to be
flushed. The result is so overwhelming, as dirt and even most stubborn deposits canbe removed and flushed away reliably with only one flush.
In order to be able to flush circular
tanks with the same positive result,the HydroSelf flushing system forround tanks was developed. The
radial flushing system operates witha mobile (flushing) container whichis connected to a central guide rod.
When the tank is filled in rainy
weather, the special closure
mechanism of the flushing container
is locked and retains the stored flush
water. After the rainfall, as soon as
the tank is empty again, the flushingprocess is initiated as the container suddenly moves upward. The flush water flows
out of the container bottom and flushes the sole of the round tank via one flushingprocess.

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Basics of HydroSelf flushing system in rectangular tanks, round tanks and tunnel sewers Dipl.-Ing. Joerg Steinhardt Dipl.-Ing.
Bernhard Hommer September 2006

2. The principle of the HydroSelf flushing system
2.1 With flushing gates in tanks and sewer tunnels
The principle of the HydroSelf flushingsystem with flushing gates is simple butvery successful. The HydroSelf flushingsystem flushes stormwater tanks andchannels highly efficiently from a low
level with the energy of the stored water.
The storage chambers are located in thearea of the structure soles at the highpoints of the sole in “flushing streets” tobe flushed within a tank or at thebeginning of flush lanes in channels. The
flush water is retained by the flushing gates until the flushing process is either
initiated automatically or by hand via unlocking the closure mechanism.

Flush water is impounded in one orseveral storage chambers and retainedby the flushing gates. (The quantity offlushing gates must be selectedaccording to the type and dimensions ofthe tank or channel.)

The sudden opening of a flushing gate
initiates the flushing process. (Severalflushing processes are initiated one
after the other, as soon as thedischarge is free again and the flushingsump empty.)

A powerful flushing wave (similar to adam break) is caused.

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Basics of HydroSelf flushing system in rectangular tanks, round tanks and tunnel sewers Dipl.-Ing. Joerg Steinhardt Dipl.-Ing.
Bernhard Hommer September 2006

The turbulent shock wave generates
enormous shear stresses andguarantees the removal of deposits
from the tank and channel soles. The
large flush water volume ensures thatthe dirt is reliably transported to thedischarge.

2.2 With a flushing container in a circular tank
The HydroSelf flushing system forcircular tanks operates with a central
flushing container, which also
constitutes the storage chamber for theretention of the flush water. The outside
wall of the container corresponds to thestorage chamber walls in facilities withflushing gates. The system of container
flushing includes the integrated central
rod, which is positioned in the centre of
the tank together with the container andto which the guide rails plus damper
and the closure mechanism areattached. Central rods which might
already exist and be necessary from thestatic point of view, e.g. of concrete inclosed stormwater tanks, can beincorporated. The surface of the tanksole in the circulating sealing area ofthe container edge must, however, be prepared in a special way and it must be
absolutely smooth and level.
Phase 1 – Dry weather
The dry weather inflow flows into thestormwater tank and then to thedischarge via the dry weather flume,
which is also used as flushing sump andis located at the outer edge.
Phase 2 - Rain
During rainfall, the tank is filled due to thethrottled discharge. This means that at
first the discharge area and then theflushing sump will fill. If the water level
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Basics of HydroSelf flushing system in rectangular tanks, round tanks and tunnel sewers Dipl.-Ing. Joerg Steinhardt Dipl.-Ing.
Bernhard Hommer September 2006

continues to rise, the closure mechanism of the flushing container will be locked. If itkeeps on raining, the tank will fill up. The flushing container will also fill, either
automatically via backwater gates or by means of an external filling installation.
Phase 3 – After the rain
After the rainfall, the tank will empty
again. The flush water will, however, beretained in the flushing container. The
stored buoyancy force generated by theinclined container walls in the lower partcannot act at the beginning, as theclosure is still locked. Only when the discharge area of the tank and the flushingsump are empty, the mechanism is unlocked and the flushing process initiated.
Phase 4 - Flushing
The control unlocked the closure. The
buoyancy force can act now and lift thecontainer wall. The flush water flows outof the container and a radial, even,powerful flushing wave cleans the entire
tank sole in the direction of the outsidewall. The flush water with the removed dirt is collected in the dry weather flume andin the flushing sump and passed on to the sewage plant via the discharge area.
3. Advantages of the HydroSelf flushing system
Advantages 1
x Specifically extended flush wave with enormous thrust force
x Also suited for longer flushing lengths with larger water quantities
x Cleaning of flushing lengths exceeding 100 m by far
x Guaranteed removal of most stubborn deposits with one flush
Advantages 2
x Storage chambers are filled automaticallyx Cleaning also with partial impoundage
x Environmentally friendly and resource saving
Advantages 3
x Simple and sturdy technology
x Low maintenance due to the application of high-quality materials
x Flushing system tried and tested in more than 1000 facilities worldwide
Advantages 4x Safety due to consultation and intensive support in the planning phasex Quick, competent and experienced service

4. Consulting the flushing system
Storm water tanks, reservoir channels and transport collectors are required, planned
and manufactured in most differing sizes, dimensions and shapes. The responsibility
for the planning usually lies with the consulting engineers. To ensure that suchbuildings can be approved, the stipulations made by cities, communities or operatingcompanies with respect to the operation must be considered and the respectively
applicable guidelines for the structural design must be complied with.
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Basics of HydroSelf flushing system in rectangular tanks, round tanks and tunnel sewers Dipl.-Ing. Joerg Steinhardt Dipl.-Ing.
Bernhard Hommer September 2006

The system drawings in the Steinhardt GmbH technical documents will provide youwith an overview on the various possibilities of how to plan a HydroSelf flushingsystem.
Tank:

Tunnel sewer:

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Basics of HydroSelf flushing system in rectangular tanks, round tanks and tunnel sewers Dipl.-Ing. Joerg Steinhardt Dipl.-Ing.
Bernhard Hommer September 2006

Round tank:

If you already have your design plans made, in many cases it is also possible toadapt the HydroSelf flushing system to the planned building. Experience has shown,however, that for the optimization of the HydroSelf flushing system, it is necessary toknow the hydraulic system of the tank or channel and its water management functionin the sewer system. The compilation below displays a selection of importantcharacteristics which should among others be included in the planning.
Tank

Large tank or small tank
Rectangular tank or circular tank
Stormwater overflow tank or stormwater retention tank
Function with the main closure or secondary closure variation
Power supply possible / not possible
Flush water supply granted

ChannelReservoir channel, transport collector
Round channel, rectangular channel, special profile
Function with the main closure or secondary closure variation
Power supply possible / not possible
Flush water supply granted

Further details with respect to construction and machine technology as well as
general hints can be found in the section “Important information for planners andoperators “ in the Technical documents relating to the HydroSelf flushing system.
Please do not hesitate to contact us for assistance in case of more complex planning
projects. Steinhardt GmbH will be happy to contribute its experience.
The most important element for flushing a tank or channel is flush water, which must
be collected and stored in the storage chambers.
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Basics of HydroSelf flushing system in rectangular tanks, round tanks and tunnel sewers Dipl.-Ing. Joerg Steinhardt Dipl.-Ing.
Bernhard Hommer September 2006

The geometrical dimensions of the tank or the channels are necessary to establish
the flush water. To this end, the required widths of the flushing gates must bedetermined. For circular tanks the size of the flushing container must be proportional
to the tank surface to be flushed.
Division (of the tank) in flushing lane
Determination of the quantity of flushing lane
Determination of the width of the flushing lane
Determination of the required flush water volume depends
Length of the flushing lane
Width of the flushing lane
Longitudinal inclination of the flushing lane
Settlements

Stand pipe DN 100

Picture of a typical storage
chamber
withstorage chamber length Lk
filling depth Tk (max. ca. 1.50 m)

Finished sole flushing lanestorage chamber width e.g.
as same as flushing lane width

The flushing sump at the end of aflushing street collects the flush water
quantity and the flushed deposits of one
flushing street. With larger facilities, thefollowing flushing process may only beinitiated if the discharge area and theflushing sump are empty again.
The content of the flushing sump [m³]should always be larger than the content
of the largest storage chamber and it
should at least feature such a dimensionthat the volume of the flush water plus
the deposits expected (e.g. ca. 30 % ofthe flush water) fit in together.

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Basics of HydroSelf flushing system in rectangular tanks, round tanks and tunnel sewers Dipl.-Ing. Joerg Steinhardt Dipl.-Ing.
Bernhard Hommer September 2006Storage chambers

Flushing sump (content > 1.3 x flush water)

5. The control of the HydroSelf flushing system
For the automatic operation of the HydroSelf flushing system, two different control
systems are available.
Purely mechanically acting float controls can be used in smaller facilities and if noelectricity is available nearby. When planning such a facility, it is, however, absolutely
imperative that Steinhardt GmbH is consulted as early as possible, as the structuraldesign of the tanks and reservoir channels must especially be adapted to the control
system and coordinated with it.
If the model of a float control is not possible, then the electrically controlled HydroSelf
flushing system will be used. The electric control is standard for larger facilities. But it
is also applied in smaller stormwater tanks and for flushing channels. The operatingease and the increased flexibility also allow to comply with the customer’s special
wishes (telecontrol system). Each electric control is suited for automatic operationand manual operation alike.
5.1 Float control (no power requiered)
The mechanically controlled hydraulic system of the HydroSelf flushing system
mainly consists of the flushing gate/flushing container with a special hydrauliccylinder, a main float, a control float and the connecting hydraulic lines.
Each individual flushing gate requires its
own main float. A control float can beused for a maximum of two flushinggates. Example: For 4 pcs. flushinggates, 4 pcs. main floats and 2 pcs
control floats are required.

The arrangement of the main and control
floats is determined depending on therespective project. The main float serves
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Basics of HydroSelf flushing system in rectangular tanks, round tanks and tunnel sewers Dipl.-Ing. Joerg Steinhardt Dipl.-Ing.
Bernhard Hommer September 2006

to lock and unlock the closure mechanism and must be capable of covering a lift
distance in a floating manner. Only after the top position has been reached, maywater flow into the storage chambers. The control float initiates the flushing process.
It must be located at a very low depth in the discharge area. For the initiation of theflushing process, the flushing sump must be empty.
Note: The flushing gate with the float-controlled HydroSelf flushing system is open in
the state of rest and it only locks in the event of rain when the rising water levelcauses the main float to float to the top.
5.2 The electric control
The electrically controlled hydraulic system of the HydroSelf flushing systemgenerally consists of the flushing gate/flushing container with a special hydrauliccylinder, the connecting hydraulic line, the hydraulic unit and the electric control (e.g.
in a safety cabinet).

All electric functional parts of the HydroSelf flushing system are located outside thestorm water tank. The hydraulic line leads from the hydraulic cylinders at the flushinggates or the container through the structure wall to the hydraulic unit (< 1.0 kW) in theexternal cabinet or control room. The hydraulic unit and the electric control can besupplied either wired ready-for-operation, mounted on a base plate or with aweatherproof safety cabinet for outdoor installation. Only the power supply and theelectrical connection must be carried out by the customer. It is also possible to realize
other installation options according to the customer’s request, e.g. in central control
rooms or the integration in larger cabinet installations.
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Basics of HydroSelf flushing system in rectangular tanks, round tanks and tunnel sewers Dipl.-Ing. Joerg Steinhardt Dipl.-Ing.
Bernhard Hommer September 2006

A hydraulic unit can also be used to control more than one flushing gate in larger
tanks by installing a larger number of valves.
For the automatic, water level-dependant control, a float switch is required. The
positions of the probes are established for each project individually, mainly, however,
above the discharge area. The flushing process is initiated, if the dischargearea/flushing sump is empty and the flush water can run off freely.
Note: The flushing gates are always closed (locked) in the state of rest with theelectrically controlled HydroSelf flushing system. Therefore water may enter thestorage chambers at any optional point in time (automatically or via external filling).
The hydraulic system is unpressurised in the state of rest. Electrical energy is only
required for a short time for the development of the pressure required to open theflushing gates.

The Steinhardt HydroSelf Flushing system
Success with a future
Taunusstein September 2006

Steinhardt GmbH,
Röderweg 8-1065232 Taunusstein,
Germany
Telefon +49 (0)6128 9165 0
Fax +49 (0)6128 916527
E-Mail info@steinhardt.dewww.steinhardt.de

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