How the exhaust valve works

The idea behind the exhaust valve is the buoyancy of the liquid on the float. The float automatically floats up until it hits the sealing surface of the exhaust port when the liquid level of the exhaust valve rises due to the buoyancy of the liquid. A particular pressure will cause the ball to automatically close. When the pipeline is running, the floating ball comes to a stop at the base of the ball bowl and lets 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 the pump fails, negative pressure will start to build up, the floating ball will plummet, and a significant amount of suction will be used to maintain the pipeline’s safety. When the buoy is exhausted, gravity causes it to pull one end of the lever down. The lever is now in a slanted position. The air is expelled from the vent hole through a gap that exists between the lever and the contact part of the vent hole. The liquid level rises with the release of air, and the float floats upward due to the buoyancy of the liquid. The sealing end surface on the lever is gradually pressed against the vent hole until the entire vent hole is completely blocked.

The importance of exhaust valves

For a very long time, people have been unable to solve the core issue of frequent water leaks in the pipe network because they do not have sufficient knowledge about whether urban water distribution pipelines contain gas and whether they may result in pipe bursts. In order to better understand the water hammer of the gas-containing type of cut-off water, it is necessary for us to explain the potential causes of gas storage during normal water supply network operation as well as the theory of the pipeline’s pressure increase and pipe-bursting.

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. The hazards can be divided into two types: explicit and hidden, and their characteristics are as follows:

The obvious hazards mainly include the following aspects

(1) Tough exhaust makes it difficult to pass water When the water and gas are in phase, the large exhaust port of the float type exhaust valve performs almost no function and only relies on micropore exhaust, causing serious “air blockage,” which prevents the air from being exhausted, causes the water to flow unevenly, reduces or even eliminates the cross-sectional area of the water flow channel, blocks the flow of water, lowers the system’s circulation capacity, raises the local flow rate, and increases water head loss. 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) (2) Because of the water flow and pipe bursts caused by uneven air exhaust, the water supply system is unable to function properly.Many pipe bursts are brought on by exhaust valves, which can let out a tiny amount of air. A water supply pipeline can be destroyed by a gas explosion caused by poor exhaust, which can reach a pressure of up to 20 to 40 atmospheres and has the equivalent destructive power of 40 to 80 atmospheres of static pressure. Even the toughest ductile iron used in engineering can suffer damage. Engineers from the College of Engineering determined after analysis that it was a gas explosion. A section of water pipe in a southern city was only 860m long, with a pipe diameter of DN1200mm, and the pipe exploded as many as 6 times in one year of operation.

The damage from the gas explosion generated by the inadequate water pipe exhaust caused by the exhaust valve can only be a tiny amount of exhaust, according to the conclusion. 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 formation 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. An uneven exhaust might cause the pipeline pressure to fluctuate, the flow adjustment to be inaccurate, the pipeline automated control to be inaccurate, and the safety protection measures to be ineffective;

2. The pipeline leaking of water has increased;

3. There are more pipeline failures, and long-term continuous pressure shocks weaken pipe walls and joints, resulting in issues including shortened lifespans and higher maintenance costs;

Numerous theoretical studies and some practical implementations have demonstrated how simple it is to produce the most damaging water hammer, which is the most dangerous to the pipeline, when the pressurized water supply pipeline contains a lot of gas. Long-term use will diminish the wall’s lifespan, make it more brittle, increase water loss, and potentially cause the pipe to explode.

The pipeline exhaust issue is the main underlying cause of urban water supply pipeline leakage. The pipeline’s bottom needs to be cleaned, and an exhaust valve that can be released is the best solution. 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%. The air is continuously expelled from the water during the delivery process and collects at the high point of the pipeline to produce air pockets (AIR POCKET), which make water delivery challenging and can therefore cause a 5–15% reduction in the system’s water delivery capacity. 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 valve body of the single-lever (SIMPLE LEVER TYPE) micro-exhaust valve has an oval form. 304S.S stainless steel is used for all internal components, including the floats, levers, lever frames, and valve seats. Inside, 1/16″ exhaust hole standards are utilized. Up to PN25 operating pressure settings are appropriate for it.