If the domestic valve design level, production level compared with foreign advanced countries have a certain gap is real, but if there is very big difference, do not necessarily match the actual. So, why the regulating valve using effect and time far less than the introduction of products? As long as the compared to China's control valve selection table and abroad calculating selection table, it is not difficult to find, we are too simple. Such as the Instrument Society of America standard format list 49 serial number, our country forms less than 20 serial number, a lot of content are not included, inevitable improper selection, not comprehensive, resulting in" be congenitally deficient"; then the regulating valve standardization level is too high, a change should be prepared, but not" an antidote against the disease", be different treat. Valve leakage only as an example, users more strongly. It not only relates to the structure of the selected. Unbalanced force is also involved in computing. Who careful consideration? Not. Since there is no necessity, cause close to death, not open, leakage, sealing reliability ( can be started, not how long does not use problem ). To solve it, you must be careful consideration, it includes:
( 1) according to the valve closing pressure difference, a calculated imbalance force, to determine the valve structure and actuator size, to ensure the closed need sufficient output power.
( 2 ) to determine the best direction for sealing.
( 3) valve structure considering, for large differential pressure, large diameter valve ( the valve such as DN100, P = 20MPa, its unbalanced thrust high up to Ft = 0.25 PI x 102 x 20 = 15.7t ), the structure of the meticulous consideration is very important, including the force balance and resistance to cavitation, erosion considerations.
( 4) don't clean medium, scaling stuttered medium anti-blockage performance considerations, blocked, jammed, how can it sealed?
( 5) the strong corrosive medium, throttling the corrosion resistance, and must be reliable, a lot of valve operation soon leaked will exceed the standard, the reason is in the throttle is corrosion.
( 6) the seal type considered.
A. Hard seal and soft seal;
B. You need wear-resistant alloy welding, improve the reliability of;
C. Soft seal and soft seal material.
( 7) leakage levels, test method, test pressure, inspection methods. Thus, the rough consideration, must get rough the use of effects: most of the general products, therefore, some ill-considered and special occasions, certain with a bad valve. To sum up, the regulating valve application main problem is: calculation, selection is not comprehensive, resulting in" be congenitally deficient"; the manufacturer of the product is single, cannot meet the needs of. The solution is: first grasp the quality to the first clearance ( also production plants do not pay much attention to the close ) clearance contract, review of the selected valve can effectively meet the working conditions and requirements, overcome" be congenitally deficient";
This was followed by the production of factory production of various products, especially the special products, variant products to adapt to the special occasion demands. To accomplish this at 2 o'clock, regardless of whether the selection of personnel and manufacturers must be proficient in the application of regulating valve.
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