How the exhaust valve works

The theory behind the exhaust valve is the liquid’s buoyancy effect on the floating ball. The floating ball will naturally float upward beneath the buoyancy of the liquid as the liquid level of the exhaust valve rises until it contacts the sealing surface of the exhaust port. A steady pressure will cause the ball to close on its own. The ball will drop along with the liquid level when the valve’s liquid level decreases. At this point, the exhaust port will be used to inject a significant amount of air into the pipeline. The exhaust port automatically opens and closes due to inertia.

The floating ball stops at the bottom of the ball bowl when the pipeline is operating to let out a lot of air. As soon as the air in the pipe runs out, liquid rushes into the valve, flows through the floating ball bowl, and pushes the floating ball back, causing it to float and close. If a tiny amount of gas is concentrated in the valve to a particular extent while the pipeline is operating normally, the liquid level in the valve will decrease, the float will also decrease, and the gas will be expelled out the small hole. If the pump stops, negative pressure will be generated at any time, and the floating ball will drop at any time, and a large amount of suction will be performed to ensure the safety of the pipeline. When the buoy is exhausted, gravity causes it to pull one end of the lever down. At this point, the lever is tilted, and a gap forms at the point where the lever and the vent hole make contact. Through this gap, air is ejected from the vent hole. discharge causes the liquid level to rise, the float’s buoyancy to rise, the sealing end surface on the lever gradually presses the exhaust hole until it is entirely blocked, and at this point the exhaust valve is fully closed.

The importance of exhaust valves

When the buoy is exhausted, gravity causes it to pull one end of the lever down. At this point, the lever is tilted, and a gap forms at the point where the lever and the vent hole make contact. Through this gap, air is ejected from the vent hole. discharge causes the liquid level to rise, the float’s buoyancy to rise, the sealing end surface on the lever gradually presses the exhaust hole until it is entirely blocked, and at this point the exhaust valve is fully closed.

1. The gas generation in the water supply pipe network is mostly caused by the following five conditions. This is the source of gas in the normal operation pipe network.

(1) The pipe network is cut off in some places or entirely for some cause;

(2) repairing and emptying specific pipe sections in a hurry;

(3) The exhaust valve and pipeline are not tight enough to allow gas injection because the flow rate of one or more major users is modified too quickly to create negative pressure in the pipeline;

(4) Gas leakage that is not in flow;

(5) The gas produced by the negative pressure of operation is released in the water pump suction pipe and impeller.

2. Movement characteristics and hazard analysis of water supply pipe network air bag:

The primary method of gas storage in the pipe is slug flow, which refers to the gas existing at the top of the pipe as discontinuous many independent air pockets. This is because the water supply pipe network’s pipe diameter varies from big to tiny along the direction of the main water flow. The gas content, pipe diameter, pipe longitudinal section characteristics, and other factors determine the length of the airbag and the occupied water cross-sectional area. Theoretical studies and practical application demonstrate that the airbags migrate with the water flow along the pipe top, tend to accumulate around pipe bends, valves, and other features with varied diameters, and produce pressure oscillations.

The severity of the change in water flow velocity will have a significant impact on the pressure rise brought on by gas movement because of the high degree of unpredictability in the water flow velocity and direction in the pipe network. Relevant experiments have demonstrated that its pressure can increase up to 2Mpa, which is sufficient to break ordinary water supply pipelines. It’s also important to keep in mind that pressure variations across the board affect how many airbags are traveling at any given time in the pipe network. This worsens pressure changes in the gas-filled water flow, increasing the likelihood of pipe bursts.

Gas content, pipeline structure, and operation are all elements that affect the gas dangers in pipelines. There are two categories of hazards: explicit and concealed, and they both have the following characteristics:

The following are primarily the clear dangers

(1) Tough exhaust makes it difficult to pass water
When water and gas are interphase, the huge exhaust port of the float type exhaust valve performs virtually no function and only relies on micropore exhaust, causing major “air blockage,” where the air cannot be released, the water flow is not smooth, and the water flow channel is blocked. The cross-sectional area shrinks or even disappears, the water flow is interrupted, the system’s capacity to circulate fluid declines, the local flow velocity rises, and the water head loss rises. The water pump needs to be expanded, which will cost more in terms of power and transportation, in order to retain the original circulation volume or water head.

(2) Because of the water flow and pipe bursts caused by uneven air exhaust, the water supply system is unable to function properly.
Due to the exhaust valve’s capacity to release a modest amount of gas, pipelines frequently rupture. The gas explosion pressure brought on by subpar exhaust can reach up to 20 to 40 atmospheres, and its destructive strength is equivalent to a static pressure of 40 to 40 atmospheres, according to pertinent theoretical estimates. Any pipeline used to supply water can be destroyed by pressure of 80 atmospheres. Even the toughest ductile iron used in engineering can suffer damage. Pipe explosions happen all the time. Examples of this include a 91 km long water pipeline in a city in Northeast China that exploded after several years of use. Up to 108 pipes exploded, and scientists from the Shenyang Institute of Construction and Engineering determined after examination that it was a gas explosion. Only 860 meters long and with a pipe diameter of 1200 millimeters, a southern city’s water pipeline experienced pipe bursts up to six times in a single year of operation. The conclusion was that exhaust gas was to blame. Only an air explosion brought on by a weak water pipe exhaust from a large amount of exhaust can cause harm to the valve. The core issue of pipe explosion is finally resolved by replacing the exhaust with a dynamic high-speed exhaust valve that can ensure a significant amount of exhaust.

3) The water flow velocity and dynamic pressure in the pipe are continually changing, the system parameters are unstable, and significant vibration and noise may arise as a result of the continuous release of dissolved air in the water and the progressive construction and expansion of air pockets.

(4) The corrosion of the metal surface will be accelerated by alternate exposure to air and water.

(5) The pipeline generates unpleasant noises.

Hidden hazards caused by poor rolling

1 Inaccurate flow regulation, inaccurate automatic control of pipelines, and failure of safety protection devices can all result from uneven exhaust;

2 There are other pipeline leaks;

3 The number of pipeline failures is rising, and long-term continuous pressure shocks wear down pipe joints and walls, leading to issues including shortened service lives and rising maintenance costs;

Numerous theoretical investigations and a few practical applications have demonstrated how simple it is to harm a pressurized water supply pipeline when it includes a lot of gas.

The water hammer bridge is the most dangerous thing. Long-term use will limit the wall’s useful life, make it more brittle, increase water loss, and potentially cause the pipe to explode. Pipe exhaust is the primary factor causing urban water supply pipe leaks, therefore addressing this issue is crucial. It is to choose an exhaust valve that can be exhausted and to store gas in the bottom exhaust pipeline. The dynamic high-speed exhaust valve now satisfies the requirements.

Boilers, air conditioners, oil and gas pipelines, water supply and drainage pipelines, and long-distance slurry transportation all require the exhaust valve, which is a crucial auxiliary part of the pipeline system. It is frequently installed at commanding heights or elbows to clear the pipeline of extra gas, increase pipeline efficiency, and lower energy usage.
Different types of exhaust valves

The amount of dissolved air in the water is typically around 2VOL%. Air is continuously expelled from the water during the delivery process and collects at the pipeline’s highest point to create an air pocket (AIR POCKET), which is used to perform the delivery. The ability of the system to transport water can decrease by roughly 5–15% as the water becomes more challenging. This micro exhaust valve’s primary purpose is to eliminate the 2VOL% dissolved air, and it can be installed in high-rise buildings, manufacturing pipelines, and small pumping stations to safeguard or enhance the system’s water delivery efficiency and conserve energy.

The oval valve body of the single-lever (SIMPLE LEVER TYPE) tiny exhaust valve is comparable. The standard exhaust hole diameter is utilized inside, and the interior components, which include the float, lever, lever frame, valve seat, etc., are all constructed of 304S.S stainless steel and are appropriate for working pressure situations up to PN25.