Backflow protection

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Backflow protection through a lifting system

Buildings are protected against the backflow of sewage from the sewer system to which they are connected by a backflow protection device or backflow stop . According to EN 12056, protection against backflow must always be provided by sewage lifting systems . If a gradient to the channel is available, the use requirements of DIN EN 12056-4 can alternatively accordance pressure flaps or other backflow according to DIN EN 13564 in the base line of the waste water system are used a building.

All drainage lines from drainage objects in buildings (washing machines, showers, hand basins etc.) form a connected pipe system through the connection to the sewer . If the sewage accumulates in the sewer z. B. due to heavy rain or sewer blockages, it pushes back into the connected house drainage pipes. There it usually rises at most to the level of the backflow level and can flood all lower-lying areas of the house such as the basement.

To avoid this, there are various options for backflow protection for house and property drainage . Flap and piston closures can be used where gravity drainage is possible (with a free slope to the sewer) and the connected drainage points can be completely dispensed with during backflow. In the event of a back pressure, piston closures close with a closing force of 1000 Newtons (corresponds to a weight of around 100 kg). Fully electronically controlled systems ensure security around the clock, even if the power grid fails.

Wastewater lifting systems or backflow lifting systems allow unrestricted use of housework or sanitary rooms in the basement, in contrast to the backflow stops, even with backflow in the sewer. The wastewater is usually pumped into a collecting pipe that is installed under the basement ceiling or outside the building. A backflow loop that runs above the backflow level reliably prevents the basement from being flooded even in the event of a power failure.

Causes of a backwater

DIN EN 12056-4 states that, in spite of dimensioning and operation according to the recognized rules of technology , backwater cannot be reliably avoided.

A backwater occurs in particular

  • increased rainwater inflow into the sewer system due to heavy rain,
  • Accumulation due to blockages, broken pipes or sewer damage,
  • Pump failure if the drainage system is emptied via a pumping station,
  • Flooding in the receiving water (often a stream or river), which means that rainwater can no longer run off in lower-lying areas,
  • Closure or overloading of the sewer as a result of repair work,
  • increased sewage inflow, among other things as a result of sewer flushing, fire extinguishing operations or additional sewage connections.

Executions

The design of lifting systems and backflow stops depends largely on whether the sewage contains faeces or similarly coarse contaminants. The products must be explicitly approved by the manufacturer for sewage containing faeces .

The backflow protection for gray water from showers, sinks and washbasins as well as dishwashers and washing machines can be carried out less complex.

DIN EN 12056-4 permits the use of backflow stops (such as backflow flaps) under the following conditions:

  • There must be a gradient to the canal.
  • The rooms must be of subordinate use so that no significant material assets are damaged or the health of the residents is impaired in the event of a backwater.
  • The user group must be small.
  • Another toilet must be available above the backflow level.
  • In the event of a backwater, it must be possible to dispense with the use of the drainage point.

Regardless of this, some municipalities prohibit the use of backflow stops and require the installation of lifting systems .

Types of backflow stops

DIN EN 13564-1 differentiates backflow traps in:

Type 0: backflow stops for use in horizontal pipes with a single self-locking element.

Type 1: Backflow stops for use in horizontal pipes with an automatic locking element and an additional (manual) emergency lock (which can be combined with the automatic lock).

Type 2: backflow stops for use in horizontal pipes with two automatic locking elements and an emergency lock (which can be combined with one of the two automatic locks).

Type 3: Backflow stops for use in horizontal lines with an automatic closing element operated by external energy (mostly electrical or pneumatic) and an emergency seal that is implemented independently of the automatic closing.

Type 4: Backflow stops that are built into drain fittings or floor drains with an automatic locking element and an emergency lock (which can be combined with the automatic lock).

Type 5: Backflow stops that are built into drain fittings or floor drains, with two automatic locking elements and an emergency lock (which can be combined with one of the two automatic locks).

Installation

Drainage points that are located above the backflow level must not be drained via backflow stops, since water running off there would escape from the drainage points below in the event of a backflow.

This also applies to lifting systems. If the system fails, there would also be an escape from the lower-lying connections.

Standards and guidelines

  • DIN EN 12056-1 Gravity drainage systems within buildings and execution requirements
  • DIN EN 12056-4 Gravity drainage systems within buildings. Sewage lifting plants - planning and dimensioning
  • DIN EN 752 gravity drainage systems outside of buildings.
  • DIN EN 1986-100 drainage systems for properties and buildings. Additional provisions to DIN EN 752 and DIN 12056
  • DIN EN 1986-3, -30 and -33 Drainage systems for land and buildings - Rules for operation and maintenance
  • DIN EN 13564-1 backflow stops for buildings - requirements
  • DIN EN 1253-5 Drains for buildings - barriers for light liquids

Web links

Footnotes

  1. ↑ Regulations and regulations ( Memento of the original dated February 12, 2018 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. ; In: Kessel.de @1@ 2Template: Webachiv / IABot / www.kessel.de
  2. ↑ a b c d e guide - protection against backflow and water in the basement, backflow stops and lifting systems , Kessel AG, January 2011