Differences between H76 and H77 check valves
The appearance of check valves H76 and H77 is very similar, and many people may mistake these two models, even thinking that H76 and H77 are the same type of valve, which is incorrect.
We can look at the differences between H76 and H77 from two aspects.
H77 Firstly, there is a comparison between H76 and H77 models. Based on the principles of valve model preparation, we can see:
H76: H-check valve, 7-wafer type, 6-double disc swing structure.
H77: H-check valve, 7-wafer type, 7-butterfly check structure.
From the model, it can be seen that the difference between H76 and H77 lies in their different structural forms.
Secondly, the structural lengths of the two are also different.
The H77 check valve is a short structure according to the national standard, while the H76 check valve is a length according to the American standard. For example, an H77 butterfly check valve with a diameter of DN100 has a structural length of 64mm; The length of H76 structure is 73mm.
Extension:
Swing check valve: A check valve with a disc shaped disc that rotates around a fixed axis outside the valve seat channel. A swing check valve is composed of a valve body, a valve cover, a valve disc, and a rocker; The valve channel is streamlined with low fluid resistance. High temperature and high pressure check valves can adopt a five flange pressure sealing structure, and the sealing ring is made of formed flexible graphite packing or stainless steel. The sealing ring is compressed by medium pressure to achieve sealing. The higher the medium pressure, the better the sealing performance.
Butterfly check valve: Similar in shape to a butterfly valve, its seat is tilted, and the rotating shaft of the butterfly plate is installed horizontally above the centerline of the valve channel, making the area of the lower butterfly plate of the rotating shaft larger than the upper part. When the medium stops flowing or reverses flow, the butterfly plate rotates to the seat based on its own weight and the reverse flow medium. This type of check valve has a simple structure but poor sealing performance. Butterfly check valves are usually used in situations where swing check valves cannot meet the requirements.
