Back flow preventer, cross connection are the weird words for those who are living in India… but these are the main part of water distribution system. Let us see briefly about back flow preventer and cross connection and its importance.
A direct/straight connection of a piping which supplies the potable/drinking water from the main line to branch lines might have the risk of contaminated water return (back flow) from branch line to the main line and it may lead health risks. Since main lines are connected to various branches and contamination in one branch line should not enter into other branch lines.
Backflow is a terminology in plumbing for an unwanted/contaminated/foul water flow of water in the reverse direction
Backflow can occur during conditions of back pressure or back siphon age
The reversal of normal flow in a system due to an increase in downstream pressure that is above the supply pressure.
Normal pressure system
Increase in downstream pressure changes flow
The reversal of normal flow in a piping system caused by a negative pressure or vacuum in the supply piping
Backflow preventer Selection needs to be based on whether the hazard on backflow will be high or low
Types of backflow preventers
1) Pressure Vacuum Breaker
2) Double Check Valve Assembly
3) Reduced Pressure Principle Assembly
Pressure Vacuum Breaker (PVB)
A pressure vacuum breaker is similar to an atmospheric vacuum breaker, except that the PVB contains a spring-loaded poppet. It only protects against back siphon age.
Double Check Valve Assembly (DC)
It contains two check valves connected in series. one check valve will still work even if the another one is jammed wide. then the closure of one valve reduces the pressure differential across the other, allowing a more reliable seal and avoiding even minor leakages. It’s also a valve used in air brake systems on heavy trucks.
Reduced Pressure Principle Assembly (RP)
The device contains two separate check valves, connected in series, with a pressure monitoring chamber. The chamber is maintained at a pressure that is lower than the water supply pressure, but high enough to be useful downstream. 4 test cocks are installed to allow a supervisor to verify proper operation of the valve with a differential pressure meter. Two gate valves are provided for maintenance
Currently, we are facing water crisis in our country. It is interesting to note that in Dubai ,US, and UK governments are supplying water to each house/flats by a centralized water distribution system. They evolved some protocol’s and systems, based on average water usage of a single person. Based on this system they provide water to every house. So water wastages are completely avoided.
To save water Hong Kong using Sea water for sanitation, Indians need to develop, improve in efficient water management Another important subject for India is to do rain water harvesting in a war like situation as we are late and need to consider this scarcity of water is a final call. We need to plan and develop a design and that should be submitted to the AHJ(Authority Having Jurisdiction ).
Some one may think, this should be implemented by our government. a lot of practical difficulties, obstacles are there. Yes agreed. But we are the plumbing professionals can able to solve all those issues. It’s our job to eliminate these myths.
Being Plumbing professionals, consultants, contractors we are dedicated to evolving new methods for water savings and hygiene water distribution without backflow of contaminated water.
“Be the Change that you wish to see in the world”