Back pressure
- Slovak term: Slovenský termín
- Back Pressure is the resistance against the flow of a fluid caused by the down stream pressure or resistance becoming greater than the supply pressure. (WHO et al. 2006).
- The reversing of normal flow resulting from a pressure downstream that is higher than the supply pressure in the distribution piping of a drinking-water supply system (WHOet al. 2006).
Explanation
Back Pressure is the resistance to the movement of a fluid in a piped system. It can be generated by gravity or head pressure, or the resistance force against a moving fluid by obstructions such as changes of direction in piping systems. The expansion of a liquid in a plumbing system due to a temperature rise can also generate a back pressure. (ASSE 2007).
Pressure is defined as force per unit area. It is usually more convenient to use pressure rather than force to describe the influences upon fluid behaviour. The standard unit for pressure is the Pascal, which is a Newton per square meter (World Plumbing Council Working Group 2008).
A pressure difference that can cause water to backflow into the water supply when a user's water system is at a higher pressure than the public water system (Symons et al. 2000).
Example
Back pressure can be found where a pump, pumping fluid through a pipe meets a resistance force, as this force increases there is a corresponding decrease in the capacity of the pump to function as designed, thus reducing the pump performance (World Plumbing Council Working Group 2008).
References
- National Plumbing Regulators Forum (2004) Plumbing code of Australia.
- Symons JM, Bradley LC Jr and Cleveland TC (2000) The Drinking Water Dictionary.
- WHO and the World Plumbing Council (2006) Health aspects of plumbing.
- American Society of Sanitary Engineering (ASSE) (2007) Plumbing Dictionary, Sixth
- Edition.
