What is Iront? An air drain valve is a safety device that can drain air in a water piping system in order to prevent air problems in water piping systems.
Purpose of using air vent valva
- To protect materials and piping systems from corrosion caused by air (oxygen).
- To prevent water splashing in the faucet due to the presence of air.
- To prevent noise from entering the hot / cold water supply systems, air conditioning system and other systems.
- For smooth operation and sustainable operation of water supply and other systems / devices through air discharge during primary water transfer.
Air conditioning only for initial evacuation
At the start of pumping for deep wells, when the aerator is needed during the start-up of the system for the initial filling of the container, such as an empty tank and pipes, the initial air is expelled, the opening force during the work is pressurized. However, the initial air is drained and the system opens the valve after reaching a regular pressure. For more information, read the Sliding Valve article .
Note for selecting the air drain valve
■ The amount of discharge
■ Features of fast discharge mechanism
Air discharge valves with fast discharge mechanism appear during operation with low pressure up to 0.015 MPa. By removing a large amount of air from the piping system at low pressure, the supply of primary waterless air in the valve is ensured.
Air discharge valve with a vacuum breaker
The vacuum cleaner valve works in the same way as the air drain valve, but it has an air inlet function that works when negative pressure is created. Prevents the flow of system current or the unit in which the water is supplied by quickly removing the negative pressure.
Necessity of vacuum valves with vacuum breaker
In order to drain the air, the “air drain valve” is installed at the top of the vertical water supply system. In this case, however, if the pressure inside the piping system decreases due to a temporary water supply suspension or accident, the pressure above the vertical piping system becomes negative, which can cause a backflow (reverse siphon) phenomenon inside the building.
For this reason, the top of the vertical piping system needs a “vacuum valve with a vacuum breaker” which has both the function of inserting enough air into the pipeline to relieve negative pressure and the function of being able to drain the air under pressure. Be
- Top of vertical pipes in residential huts and buildings
- Top of vertical pipes connected to reinforce direct water supply lines
Display of the amount of incoming air
One of the possible reasons for the maximum negative pressure in water supply piping systems is high water leakage due to damage to the pipeline. Therefore, if more air enters the pipe from this water leak, no more negative pressure is created.
Air intake performance standards in the Nordic countries (founded by N. Lindblad, Swedish Water and Sewerage Association) agree on the amount of air intake
The Nagoya Water and Sewerage Authority and some other business units determine the amount of incoming air for each nominal size of vertical pipes based on the opinion of the Scandinavian countries.
Amount of air required (Nagoya City Water and Sewerage Office)
ΔP = -2.9kPa
Examples of negative pressure accidents in the vertical piping system
In an apartment with an automatic hot water function with fully automatic hot water supply, the accident occurs when the hot water from the upper floors of the bathtub comes out of the lower floors of the faucet.
Disconnection of water supply pump (water cut) is due to power outage.
Negative pressure occurred inside the vertical piping system.
Residents downstairs turned on the tap.
Reverse flow from inverted siphon.
Although there were three control valves between the bathtub faucet and the faucet to prevent backflow, the hot tub water came out of the downstairs faucet due to the failure of the operation.
* Valve review is structurally improved and reliability is increasing.
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