Function of ventilation check valve in toilet

The integrated ceiling was installed in the bathroom at home, and the master of home testing said that there was no need to install a check valve, saying that the check valve would ring in windy weather after installation. But if you don't pretend, will there be mosquitoes flying in or something? Understand the working principle of bathroom ventilation check valve with Bian Xiao.

The working principle of check valve is briefly described as follows.

Check valve refers to the valve that automatically opens and closes the disc depending on the flow of the medium itself to prevent the medium from flowing backwards, also known as check valve, one-way valve, reverse flow valve and back pressure valve. Check valve is an automatic valve, its main function is to prevent the medium from flowing backwards, prevent the pump and driving motor from reversing, and release the medium in the container.

Check valves can also be used in pipes supplying water to auxiliary systems, in which the pressure may rise above the system pressure. Check valves can be mainly divided into swing check valves (rotating according to the center of gravity) and lifting check valves (moving along the axis). The function of this valve is to only allow the medium to flow in one direction and prevent the medium from flowing in the other direction. Usually, this valve works automatically. Under the action of unidirectional fluid pressure, the disc opens. When the fluid flows in the opposite direction, the fluid pressure and the self-overlapping disc of the disc act on the valve seat, thus cutting off the flow.

Among them, check valves belong to this type of valves, including swing check valves and lifting check valves. Swing check valve has a hinge mechanism, and a disc like a door is freely supported on the inclined seat surface. In order to ensure that the disc can reach the proper position of the valve seat surface every time, the disc is designed in the hinge mechanism, so that the disc has enough swing space to make the disc truly and comprehensively contact with the valve seat. According to the performance requirements, the disc can be completely made of metal or inlaid with leather, rubber or synthetic materials.

When the swing check valve is fully opened, the fluid pressure is almost unimpeded, so the pressure drop through the valve is relatively small. The disc of the lifting check valve is located on the sealing surface of the upper valve seat of the valve body. This valve is similar to a globe valve except that the disc can be lifted freely. The fluid pressure makes the disc lift from the sealing surface of the valve seat, and the medium backflow makes the disc fall back to the valve seat, cutting off the flow.

Depending on the service conditions, the disc can be all-metal structure, or it can be in the form of embedding rubber pads or rubber rings on the disc frame. Like the globe valve, the passage of fluid through the lift check valve is very narrow, so the pressure drop through the lift check valve is greater than that of the swing check valve, and the flow rate of the swing check valve is rarely limited.

According to the structure and installation mode of check valve, it can be divided into two types:

1 swing check valve: the disc of swing check valve is disc-shaped and rotates around the axis of the seat passage. Because the flow channel in the valve is streamlined, the flow resistance is smaller than that of the lift check valve. It is suitable for large-caliber occasions with low flow and constant flow, but it is not suitable for pulsating flow, and its sealing performance is not as good as that of lifting check valves. Swing check valves are divided into three types: single disc, double disc and multiple disc. These three types are mainly divided according to the valve caliber, in order to prevent the medium from cutting off or flowing back and weaken the hydraulic impact.

Lift check valve: a check valve whose disc slides along the vertical center line of the valve body. Lift check valves can only be installed on horizontal pipelines, and the disc can be a ball on a high-pressure small-caliber check valve. The body shape of the lifting check valve is the same as that of the globe valve (generally available), so its fluid resistance coefficient is large. Its structure is similar to the cut-off valve, and the valve body and disc are the same as the cut-off valve. The upper part of the valve disc and the lower part of the valve cover are provided with guide sleeves, which can freely rise and fall in the guide sleeves of the valve lamp. When the medium flows downstream, the valve disc is opened by the thrust of the medium, and when the medium stops flowing, the valve disc falls vertically on the valve seat to prevent the medium from flowing backwards. The direction of medium inlet and outlet channel of straight-through lifting check valve is perpendicular to the direction of valve seat channel; Vertical lifting check valve, the direction of medium inlet and outlet channel is the same as that of valve seat channel, and the flow resistance is smaller than that of straight-through type.

Disc check valve: a check valve in which the disc rotates around the pin in the valve seat. Disc check valve is simple in structure and can only be installed on horizontal pipeline, so its sealing performance is poor.

4 pipeline check valve: a valve with a disc sliding along the center line of the valve body. Pipeline check valve is a new type of valve with small volume, light weight and good processing technology, and it is one of the development directions of check valves. But the fluid resistance coefficient is slightly larger than that of swing check valve.

5 compression check valve: this valve is used to cut off boiler feed water and steam, and has the comprehensive functions of lifting check valve, globe valve or angle valve.

In addition, there are some check valves that are not suitable for pump outlet installation, such as bottom valve, spring type and Y type check valves.

Finally, it is worth mentioning that no matter how well the bathroom is ventilated, we should pay attention to what to do if the bathroom is not well ventilated. Bian Xiao believes that in order to effectively prevent accidents caused by poor ventilation in the bathroom, it is necessary to have a little knowledge of bathroom safety and install ventilators, so that any potential safety hazards in the bathroom can be dealt with in time. Therefore, tragic accidents can be avoided.