The design knowledge of Check valve slow-closing structure

Open check valves pipeline system as a downstream upstream, close the valve, mainly used to prevent the media back, to prevent the pump and drive motor reversal and the container medium discharge; the most commonly used is the valve around the valve pin rotation of the Swing Check Valves and the valve flap along the vertical lift center the line to move the valve, but the above 2 kinds of valves are closed when the media back speed from the largest decrease to zero rapidly, resulting in water pipes and pipe internal pressure rises rapidly, resulting in water hammer damage to pipeline system, so the general check valve production diameter of 50 ~ 500 mm (1). Water hammer effect to reduce the check valve, check valve used to expand the scope, the original product design basis, an additional relief valve closed deputy, solve the problem of pipeline water hammer boost.
1, the swing check valve with improved structure
In the original swing check valve slow closing Dual Plate Check Valves is additionally arranged on the side. Vice valve installed in the main valve flap side or both sides and connected with the normal flow of medium, medium pressure when the valve is opened, the Deputy valve is opened, the medium into the main valve outlet end through the auxiliary valve hole, so that the main valve inlet end pressure, the main valve valve opening, the main valve and pressure tends to balance; upstream medium, the main valve quick closing in countercurrent medium, while the upper side valve body for the buffer cylinder, vice valve cover is screwed into the valve body upper cover a hole, the Deputy valve and piston rod empty set of a certain gap, O type rubber ring seal between the piston and the buffer cylinder the lower part of the piston and the valve flap, between the flat seal; when the vice valve main valve with closed and closed, due to side valve cover holes in the role, through the medium of small gradually into the vice valve buffer cylinder cavity, the gap between the back part of the medium vice valve and piston rod, thus vice valve piston is slowly closing the. The structure of the main valve off the equivalent of fast closing phase, the Vice-valve slowly off the equivalent of the slow closing phase, based on hydraulic and mechanical transition mechanism of pumping unit shows that the structural design can effectively prevent water hammer boost.
2, lift check valve with improved structure
Lift Wafer Check Valves also known as the end, it can maintain the required suction pump to stop the water column (2); improvement of the valve structure is additionally provided with a slow closing valve as shown in Figure 2 in the main valve between the valve flap and valve stent.
The valve body and the bottom net is arranged between a pad ring, in addition to the increase in the valve seal height; buffer piston and cylinder cushioning rubber, the valve shaft and piston rigid connection, the buffer cylinder and a smaller gap between the valve flap shaft. When the medium downstream, the pressure medium open the valve flap into the main body cavity, while promoting the buffer piston upward; when the medium back, due to open within the buffer tank is filled with media, while the buffer tank and smaller gap between the valve flap shaft, so with the buffer medium in the cylinder is gradually passed through the gap, the main valve valve valve play a role of buffering, the pipeline water hammer pressure to control (Figure 2).