A pressure reducer (or pressure reducing valve , reducing valve , back pressure regulator ) is a pressure valve for installation in a hose or line system that, despite different pressures on the inlet side (inlet pressure, inlet pressure), ensures that a certain outlet pressure (outlet pressure) is not exceeded on the outlet side .
Layout and function
The two central components of a pressure reducer are the pressure sensor and the valve coupled to it . The designs can differ depending on the intended use, the medium ( gas or liquid ) and the expected pressures, but the principle remains the same: The pressure on the outlet side acts on the diaphragm on one side and on the other (in the schematic drawing the lower) the air pressure and an adjusting spring act. The membrane is mechanically coupled to the valve. The higher the pressure on the outlet side, the more the valve is closed; when the (adjustable) target outlet pressure is reached, it shuts off the flow. If this closing does not take place completely because a seal is damaged or contaminated, the outlet pressure can slowly rise to such high values that a safety valve opens and blows off.
For target output pressures from 1 bar, the pressure reducer can be built with a piston as a pressure transducer instead of a diaphragm and therefore very compact. The first stages of diving and breathing apparatus and latex balloon filling valves are all piston-controlled.
The maximum static pressure in water supply networks is 2.0 bar below the maximum system operating pressure (Maximum Design Pressure MDP). According to DVGW AB W400 Part 1, water supply networks are limited to a min. System operating pressure should be designed to be 10 bar in order to be able to adequately supply higher-lying consumers. Pressure reducers reduce the pressure for houses or apartments to at least 2 bar, with an additional 0.35 bar to be added for each additional floor. This ensures that the pressure resistance of hot water storage tanks and the adequate function of water taps are taken into account. Gas is transported in urban areas via high or medium pressure networks and, in district control systems (stations) with pressure reducers, brought to the pressure level of the low pressure networks to supply domestic and commercial consumers. Low pressure networks are z. B. operated with the pressure levels 22/23, 50 or 90 mbar. Conventional gas systems (in single or multi-family buildings) have a flow pressure between 22 and 25 mbar to supply heat generators .
When scuba diving with compressed air or another breathable gas mixture, the compressed air cylinders are filled with a pressure of 200 to 300 bar . The first stage of the regulator reduces the pressure to around 10 to 15 bar. This medium pressure is reduced once more to the ambient pressure by the second stage (with the mouthpiece). The water pressure increases by around 1 bar for every 10 m difference in altitude, so that (taking into account the atmospheric pressure of 1 bar) there is a pressure of around 3 bar at a depth of 20 m.
Pressure reducers are also used in the medical supply with oxygen or anesthetic gas (laughing gas) as well as in good balloon filling valves for helium.
When operating heaters or gas stoves with butane or propane gas bottles (e.g. in the camping area), a pressure reducer is connected to the bottle fitting , which increases the bottle pressure (vapor pressure above the liquid gas) from approx. 10 bar to the operating pressure of the device of 30 or 50 or 150 mbar. The pressure reducer also enables the use of rubber hose lines which would burst when loaded with full cylinder pressure . The use of liquid gas in recreational vehicles (mobile homes, caravans) is described in DVGW worksheet G 607.
Pressure reducing valves are used in central compressed air systems, as can usually be found in production halls , to reduce the pressure from the system pressure, usually 10 to 13 bar, to the pressure required for the workplace.
- Animations (see Pressure Animations)
- TomTank: Explain: The function of a pressure reducer - SBZ fitter. October 6, 2013, accessed on July 28, 2020 (de-sbzm).