Air vent (valve)
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The task of deaerators is to remove gases, in particular air, from a liquid-carrying system in pipelines and containers. Vent valves are among the fittings . It makes sense to install vents at the highest point of a water-bearing pipeline system, as air has a lower density than water. Colloquially, ventilators are also referred to as "sniffer pieces".
For larger versions, see degasser .
Principles
A distinction is made between mechanical and thermal ventilators.
Types
Some types of air vent are:
- Air vent (manual)
- automatic vent valve with float
- Expanded body vent (swelling body principle)
Air vent
Air vent taps are the simplest form of air vent. It only consists of a tap that is opened for ventilation and closed again when all the air has escaped.
Automatic vent valves
With float
In contrast to other ventilators, this type of vent valve consists of a component that is equipped with a float. This is pushed up by the water so that the valve closes and no water can escape. When air collects on the float, the ball sinks down and releases the valve, allowing the air to flow out. Once the air has escaped through the valve, the water pushes the float up again and closes the valve again. The disadvantage here is that these ventilators are more susceptible to wear and therefore more maintenance-intensive than other forms of ventilator. Therefore, they must always be placed in easily accessible places. Air vents are used in various areas, especially in building services. This is the ventilation of radiators and heating systems as well as boilers and the ventilation of water heaters by means of a heat exchanger . Most European countries require a permit for boiler ventilation for use in domestic water systems . The industrial application of ventilators comes e.g. B. in the context of liquid nitrogen (N 2 ), liquid argon (Ar) and liquid oxygen (O 2 ). For this application, ventilators made of gray cast iron cannot be used, because the extreme cooling of the component by the liquefied gases changes the material structure in such a way that the material can no longer be used for pressure lines. Here, ventilators are used that are made entirely of stainless steel and welded . An automatic vent made of stainless steel is completely maintenance-free .
With swelling body
The most common variant of simple auto ventilators for radiators is based on materials that swell as soon as they come into contact with water. The swelling leads to an increase in volume, which causes the seal. One of the simplest and earliest designs is likely to be a cork stopper in a piece of pipe as an enclosure. Even when the cork body is in close contact, air can still escape very easily due to the low viscosity of a gas as long as the cork is dry. Once the air has escaped, however, the cork comes into contact with the water, and the swelling causes the cork body to press against its surround or against a closure device, so that no more water can get past. In contemporary designs, swelling discs made of special cellulose are used according to the same principle, which expand by 50% when water is absorbed.
Individual evidence
- ↑ What is a sniffing piece? Retrieved September 1, 2019 .
- ↑ Data sheet ( Memento of the original from January 29, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. at weinmann-schanz.de
