subject: Choosing The Kind Of Devices For Backflow Prevention [print this page] What happens when contaminants or foreign objects enter into your potable household water system? The result will be unsafe drinking water coming out of every faucet in your home. This occurrence is backflow. In your water system, there are two directions for water. From the source is clean water that will flow and come out of your faucet. The other is the used and unclean water from your drains that are to be eliminated. When backflow happens, a portion of the unclean water goes back to the water source. Thus the water flowing from therein will have contaminants.
One reason for the backflow is too much pressure in one point of the system. A negative pressure in the water line will also cause backflow. For either of these cases, backflow prevention is the solution. This will keep the drinking water free from contaminants.
There are different kinds of backflow preventers. Despite their differences, all these equipments function in the same manner which is to prevent dirty water flowing back to the water source. The choice of the kind of device can be dependent on the situation of your water system.
Here are 6 of the common backflow preventer devices.
Atmospheric vacuum breaker
This elbow-shaped device is bent at right angle. Installed inside this device is a valve that prevents the backflow.
Air gap
This is the most common backflow preventer used in majority of houses. An air gap exists between the sink and the head of the faucet. The faucet is made to flow at night during winter season to prevent the water from freezing. Frozen water can cause the pipes to burst. Furthermore, the flow of water will release the pressure which eventually prevents the backflow of water.
Hydrostatic loop
This backflow preventer device consist of several pipes that are vertically assembled. The installed loop prevents the backflow.
Double check valve
This device makes use of assembled gate or valve gate at each of the two ends. This allows for testing and isolation and the valve on the end will reverse the normal flow. This is its use as a backflow preventer.
RPZD
This is the device for homes that have low pressure. This has a chamber in between the separate check valves. This is where pressure is monitored and it is here where the water pressure is retained at the right level. This device keeps the water supply from contamination.
Chemigation valve
This is a device that is more applicable under agricultural setting. The function is to prevent the toxic chemicals like fertilizer and pesticide from contaminating the water. It has a flapper in its check valve and the function is to ensure that the water flows in only one direction. It is equipped with an injection part that will set the downward flow of chemicals.
The use of these devices will depend on the individual situation in a house, except of course for the chemigation valve which is definitely better used in agricultural areas.
