Reciprocating cryogenic liquid pump is the cryogenic liquid (such as liquid oxygen, liquid nitrogen, liquid argon) pressurized filling bottles or pipes to oxygen at low temperature equipment, with its simple structure, stable and reliable operation, safe and economical, low speed And other features by users of all ages. The suction valve and the discharge valve in the reciprocating pump are the core of the pump. Therefore, the service life of the discharge valve is one of the important factors that affect the performance of the reciprocating pump. The basic requirements of the valve are: (1) a good seal when closed, no liquid stringing. (2) The opening and closing of the valve should be coordinated with the movement of the piston, otherwise the leakage of cryogenic liquid due to the hysteresis of the valve will reduce the volumetric efficiency of the pump. (3) require the valve to work smoothly, especially when the valve is closed, there is no serious impact phenomenon, the guide should be flexible, no stuck phenomenon. (4) cryogenic liquid flow through the valve, the resistance loss should be small. (5) Simple structure, better processing technology, easy maintenance. (6) to have sufficient strength and stiffness, wear resistance is better, longer life. 1 valve movement law According to the valve plate downforce balance and fluid mechanics Bernoulli equation and fluid flow through the valve clearance (orifice) when the flow formula can be obtained valve lift hv, velocity V and acceleration a and angle Φ relationship. It can be seen that the valve speed is positive and the acceleration is negative in the range of Φ from 0 to π / 2. When the valve is rising, it is a kind of slow motion. In the range of Φ equal to π / 2 to π, the valve flap descends, the valve speed is negative, and the acceleration is also negative, indicating that the valve flap is a kind of growth movement when it falls, which will strengthen the impact on the valve seat. Due to the fact that the valve is continuously moving during operation, there is a phenomenon of Weisiteer that does not rise at the moment when the discharge stroke starts. After a lag angle, the valve starts to move and lags the piston. At the end of the discharge stroke, the valve is not closed and stays at the height of the lift hmax until the valve is closed after a lag angle. 2 valve type and structure type There are many types of discharge valve, such as flat valve, ring valve, cone valve, spherical valve, etc., but its opening and closing of the force, are relying on the valve before and after the liquid pressure difference to carry out. Now on the two typical structure for a comparison, the structure shown in Figure 2, Figure 3. With spring plate valve (Figure 2), the general selection of stainless steel stem material and the use of brass seat material, the impact of the collision between the two larger, shorter valve life, the valve stem often need to study the seat. Figure 3 spool material for the use of PTFE, the valve seat material is brass, the impact of the collision between the two smaller, longer valve life, and its simple structure, easy maintenance. Practice has proved that in the case of large flow, high pressure, the latter is better than the former, filling the bottle the higher the pressure, the greater the reverse pressure, the easier the valve seal. The latter as a wearing parts, the cost is much lower than the former. However, in the case of low flow and low pressure, the latter is ineffective. Valve hysteresis makes the valve can not be closed in time, due to low pressure conditions, the pressure difference is too small, but also no spring force to promote timely valve action, often resulting in pressure on the fight. In general, pumps with less than 150 L / h should be pre-drained, while pumps with more than 150 L / h can use the latter's simple draining valve for significant economic benefits. The two are usually designed to be designed interchangeable installation, according to the actual situation of choice. Wide range of model selection from 65 to 90 series.The most precise irrigation, the remarkable energy saving and 100% well-distributed water jet.15 years of service life for the basic unit and ten years' service life for PE pipe.Simple assembling, easy handling and safe operation.Efficient water saving, the water-saving rate can be over 75%. Hose Reel Irrigation-aquago 40mm Water Irrigation System,Orbit Sprinkler System,Above Ground Sprinkler System,Smaller Sprinkler Hose Reel Shandong H.T-BAUER Water and Agricultural Machinery & Engineering Co., Ltd. , https://www.ht-bauer.com