Exhaust valves are used for pipeline exhaust in independent heating systems, centralized heating systems, heating boilers, air conditioning, floor heating, and solar heating systems.

Principle
When there is gas overflow in the system, the gas will climb up the pipeline and eventually accumulate at the high point of the system. The exhaust valve is usually installed at the high point of the system. When the gas enters the exhaust valve chamber and accumulates at the upper part of the exhaust valve, as the gas inside the valve increases, the pressure rises. When the gas pressure is greater than the system pressure, the gas will cause the water level in the chamber to drop, and the float will drop along with the water level, opening the exhaust port; After the gas is exhausted, the water level rises and the float also rises. Close the exhaust port. Similarly, when negative pressure is generated in the system, the water level in the valve chamber drops and the exhaust port opens. As the external atmospheric pressure is higher than the system pressure at this time, the atmosphere will enter the system through the exhaust port to prevent the harm of negative pressure. If the valve cap on the exhaust valve body is tightened, the exhaust valve will stop discharging. Normally, the valve cap should be in the open state. The exhaust valve can also be used in conjunction with a block valve for easy maintenance of the exhaust valve.
characteristic
1. The float of the exhaust valve is made of low-density PPR and composite materials, which will not deform even after prolonged immersion in high-temperature water. It will not cause difficulties in float movement.
2. The float lever is made of hard plastic, and the connection between the lever, float, and support is made of movable connection, so it will not rust during long-term operation, which may cause the system to malfunction and result in water leakage.
3. The sealing end face of the lever is supported by a spring, which can expand and contract correspondingly with the movement of the lever, ensuring sealing without exhaust.
Installation: The exhaust valve should be installed together with the block valve during installation, so that when the exhaust valve needs to be removed for maintenance, the system can be sealed and water will not flow out. Low density PP material, which will not deform even after prolonged immersion in high-temperature water.
Operation Method
When water starts to be injected into the pipe, the plug stays in the open position for a large amount of exhaust. When the air is exhausted, water accumulates in the valve, and the floating ball is lifted. The plug is driven to the closed position to stop a large amount of exhaust. When the water in the pipe is transported normally, if a small amount of air accumulates in the valve to a considerable extent, the water level in the valve drops, and the floating ball also drops. At this time, the air is discharged through the small hole. When the pump stops, the water flow in the pipe is empty, or when negative pressure is generated in the pipe, the plug quickly opens to suck in air and ensure the safety of the pipeline.
Technical Requirements
① Main technical parameters
a. The nominal pressure of the exhaust valve is PN10.
b. The sealing test pressure is 1.1MPa.
c. The strength test pressure is 1.5 MPa.
d. The water closing pressure of the exhaust valve should be ≤ 0.02 MPa.
e. The air closing pressure of the exhaust valve should be ≥ 0.07 MPa.
f. The pressure test shall comply with the provisions of standard GB/T13927.
g. The connecting flange shall comply with the provisions of standard GB/T17241.6-98.
h. The high working pressure can reach 10 bar.
i. The high working temperature (water) is about 110 ℃.
② Performance requirements
a. The exhaust valve should have a large exhaust capacity, which can quickly restore the normal water supply capacity in a very short time when the pipeline is filled with water.
b. When negative pressure is generated inside the exhaust valve, the piston should be able to quickly open and quickly draw in a large amount of external air to ensure that the pipeline is not damaged due to negative pressure. And it can discharge the trace air accumulated in the pipeline under working pressure.
c. The exhaust valve should have a relatively high air closing pressure, and within a short period of time before the piston closes, it should have sufficient capacity to exhaust the air in the pipeline and improve water delivery efficiency.
d. The water closing pressure of the exhaust valve should not exceed 0.02 MPa, and the exhaust valve can be closed under lower water pressure to avoid a large amount of water gushing out.
e. The exhaust valve should use stainless steel floating ball (floating bucket) as the opening and closing component.
f. The exhaust valve body should be equipped with an anti impact protection inner cylinder to prevent premature damage to the floating ball (floating bucket) caused by high-speed water flow directly impacting the floating ball (floating bucket) after a large amount of exhaust.
g. For exhaust valves with DN ≥ 100, a split structure is adopted, consisting of a large number of exhaust valves and automatic exhaust valves, to meet the requirements of pipeline pressure. The automatic exhaust valve should adopt a double lever mechanism to greatly increase the buoyancy of the floating ball, and the closing water level is low, making it difficult for impurities in the water to contact the sealing surface. The exhaust port will not be blocked, and its anti blocking performance can be greatly improved. At the same time, under high pressure, due to the force application of the lever, the floating ball can descend synchronously with the water level, and the opening and closing parts will not be sucked up by high pressure like traditional valves, thus allowing normal exhaust.
h. For working conditions with high flow rate, frequent start of water pump, and DN ≥ 100 diameter, a buffer plug valve should be installed on the exhaust valve to reduce water flow impact. The buffer plug valve should be able to prevent a large amount of water spray without affecting a large amount of exhaust, so that the water delivery efficiency is not affected, and effectively prevent water hammer from occurring.