The check valve for ventilation is aimed at eliminating reverse air flow in ventilation systems if the fan turns on. When the ventilation system is turned off, it is impossible to allow outside cold air to enter the room through the exhaust duct, in addition, this allows the ventilation to be protected from the penetration of midges, dust and other things.
The check valve for ventilation can be installed vertically or horizontally depending on what tasks it faces. If it is installed in a vertical position, then it is important to consider that the air flow should have a direction from the bottom up. When installed horizontally, it is important that the flow rate is more than six meters per second, and when installed vertically, more than four.
The check valve for ventilation has the form of a blade mounted on the axles and placed in the housing. A cylindrical counterweight is attached to the axis, which allows to keep the blade in the closed position with the fan turned on, allowing it to open as smoothly as possible when the air flow begins to move. The connecting flanges of the valve are equipped with a number of standardly located openings designed for its rigid placement in the duct or pipe.
The non-return valve for ventilation, the price of which is quite affordable, can be one of two types: have a section in the form of a circle or a rectangle. The most common round version of the type of "butterfly". It is a structure on the axis of which a pair of petals is fixed, which divide the valve into two parts. Air can pass only in one direction, since the petals are specially spring loaded for this. If the flow goes back, then they close. In this case, there is one significant drawback: there is a high probability of jamming due to freezing in one of the positions.
The air non-return valve for ventilation can be used in domestic exhaust systems. Sometimes an unpleasant odor seeps into the hoods in the bathroom from neighboring apartments. In this case, an excellent way out of the situation is to install a hood with a check valve. It does not allow air from the ventilation shaft to appear in the room if the fan is in the off state. When it is turned on, there will be an outflow of air flow into the mine.
An inertial grate, which is installed externally, is often used as a check valve. Its device is focused on the ability to open the blinds in only one direction, so when the hood is turned off, it will close. It is worth noting that some operating conditions can cause even the inertial grating to stick. This factor should be considered when designing ventilation. With the right approach to this issue, you can achieve excellent results.
So, the check valve for ventilation can be made in the form of a traditional device of a fairly simple design or in the form of an inertial grating. Belonging to a certain type implies special conditions for the installation of the device.