TECHNOLOGY AND ECONOMY IN OUTFLOW SYSTEMS

Technology Considerations

A The Toilet

Created in England, in the late 19th century, under the name of water closet, the toilet, as well as in-building facilities for water and sewage, constituted a remarkable technological breakthrough that allowed people to move from the countryside and concentrate in urban centers. Nowadays, a toilets is an anatomical shaped container, with a water well intended to receive the waste of human physiology, and an internal device able to flush it with a stream of water.
Hydrodynamic energy used in the process is provided by a flushing device, which supplies the toilet with water in a volume and speed suited, not only to remove the waste deposited in the toilet, but also to lead it through the sewer pipe in a horizontal direction, until it reaches the fall pipe of the building.

Water, a Limited Natural Resource

Older toilets required large volumes of water, being responsible for the high use of water in households. In 1997, following the example of what had been done in developed countries, the Ministry of the Interior, through the Brazilian Program of Quality and Productivity in the Habitat (PBQP-H), established guidelines to reduce the water use in toilets. Maximum volumes of water, for cleaning toilets, were established, to be adopted gradually by the year 2002. According to this government determination, by the year 1999, toilets, in Brazil, should use no more than 12 liters of water per discharge. Starting in 2000, the maximum volume allowed per discharge was 9 liters. In 2002, this was reduced to 6 liters, the volume adopted by the European Union
and the United States.

Anticipating the new regulations deadlines, all toilet manufacturers took the initiative to launch toilets with reduced discharges designed to work with only 6 liters of water. In order to establish and monitor the volume of water consumption toilets must be provided with a cistern, which by its own nature can only release the volume of water in its reservoir.
In practice, it is impossible to control the discharge volume released by fluxible valves, thus, the use of this type of device is doomed to disappear.

An Integrated System

The toilet is, in fact, only one of the components
of an integrated system consisting of:
toilet
cistern
sewer pipe

For this system to work effectively, with low discharge volumes as established by present standards there needs to be a perfect harmony between the
three components.
The operation of the system takes place in three different stages.
The first phase, which should consume no more than 40% of the volume of water in the tank, is designed to break the inertia of liquids and solids stationed in the toilet bowl,
and toss them in the sewer system.
In the second phase, another 40% of the volume of the discharge acts as a water plunger, consisting of clean water that keeps the initial flow of effluents in motion, inside the horizontal segment of the sewer pipe, until they reach the fall pipe of the building.
The remaining 20%, at the end of the discharge, are intended to refill the toilet
and recover the water system closure, preventing the seepage of gases and odors
in the bathroom.

The satisfactory performance of a low consumption toilet, therefore, depends on its ability to remove all solid waste with 40% of the initial discharge, with, at least, 2.5 liters of clean water left to carry the waste to the system output pipe.
Whereas, volume, density and the nature of solids deposited in toilets, as well as the horizontal sewer pipe distances, vary from case to case, it is necessary that the hydrodynamic energy applied in the process be compatible with the type of toilet, and energetic enough to meet extreme situations.

The Intelligence to Put The Right Things In The Right Place

The smarter way to create an efficient discharge for a toilet is to install the cistern inside the wall of the bathroom. The installation of in-wall cisterns provides many benefits for both the contractor and the client.

A- It enables the installation of the cistern in the highest position, ensuring a better flow and velocity of the discharge for smooth operation with siphoning or drag toilets;
B- It allows the installation of the toilet closer to the wall, with consequent gain of useful space, enabling the construction of comfortable bathrooms, even those of small dimensions;
C- Are fully compatible with toilets with horizontal outputs, as well as, suspended toilets used in rational bathrooms where the horizontal segment of the sewer pipe is installed inside the drywall walls and above floor level;
D- Can be installed inside of both, masonry walls, and conventional drywall walls.

 

Types of Toilets

Toilets can be configured to operate
by siphoning or drag.

By Siphoning
Conventional toilets
that work by siphoning discharge sewage downwards.

By Drag
Toilets with horizontal output by drag. This type of basin is used in rational bathrooms, where the sewer pipe is installed inside drywall walls above floor level. The operating system by drag can direct the flow both horizontally
or downwards. Horizontal output toilets can be supported on the floor or suspended, that is, fixed on the bathroom wall.

Low Water Use Toilets

Toilets With Siphon Action
In toilets with siphon action, the discharge water is introduced inside the well through a distribution collar on the upper part of the vessel. Guided by the slope of the bowl walls, the water flow converges to the bottom.

Hydrodynamic energy resulting from volume and discharge flow sets in motion the mass consisting of liquids and solids, placed inside the bowl, transferring it to the siphon located inside the bowl.
The siphon action sucks the rest of the contents of the bowl into the sewer pipe located below the floor slab.
To allow the siphon action to work with reduced volumes of water it is necessary, not only to decrease the size of the bowl’s well, but also to reduce the diameter of the siphon.
Reducing the diameter of the siphon, capacity to pass solid waste of greater volume is reduced, with the consequent increase in the risk of clogging.
Siphon toilets, with low water consumption, coupled to a reduced flow tank (1.4 l/sec), work very close to adequate limits, leaving, with annoying frequency, residues after the discharge, making it necessary to flush the toilet twice to complete cleaning.
For this type of toilet to work properly, it is necessary to use a cistern installed in the highest position, capable of delivering at least a flow of 1.7 l/sec.



Drag Toilets

In this kind of toilet, the effluent stream is expelled from the well of the bowl directly to the sewer pipe, through a large diameter duct that allows clear passage of liquid and solid mass effluents, independent of their nature, volume or density.
The transfer of effluents from the bowl to the sewer pipe is made exclusively by hydrodynamic energy generated by the discharge of water in the process.
For this type of bowl to work effectively, it is necessary to generate a speed of 1.7 to 2.2 liters per second for the water discharge. The higher the flow rate, the greater the ability to remove solids from the well of the toilet, the better the flow of sewage in the horizontal leg to the fall pipe, and the better system performance as a whole.
Consequently, drag toilets, of low consumption (6 liters), must, be associated with cisterns installed in an elevated position, able to provide high flow discharges (1.7 to 2.2 l/sec).

1.4 l/sec (insufficient flow)
1.7 to 2.2 l/sec (adequate flow)