Caliber calculations are generally not required for straight-through single-seat quick-opening valves, but when it is close to the equipment behind the valve, in order to prevent the high-pressure medium from impacting the equipment when the valve is quickly opened, the caliber calculations must be performed on the straight-through single-seat quick-opening valves. Methods as below:
Before choosing a straight-through single-seat quick-opening valve, you must understand the detailed process parameters and control requirements, and make a preliminary judgment based on the process parameters and control requirements whether you can use a straight-through single-seat quick-opening valve. If you can choose a straight-through single-seat quick-opening valve, then Perform detailed calculations of flow coefficient, noise and unbalanced force according to the process parameters, and finally select the detailed configuration of the valve according to the calculation results. The calculation and selection steps of the straight-through single-seat quick-opening valve are as follows.
a) Understand the detailed process parameters and control requirements.
b) According to the process parameters and control requirements, it is preliminarily judged whether the straight-through single-seat quick-opening valve can be used. If the medium is clean and free of impurities and does not contain fibrous materials, you can choose a straight-through single-seat quick-opening valve, such as steam, water, nitrogen, hydrogen, gasoline, diesel, etc.
c) Calculate the maximum flow coefficient Kv value. Generally, it is calculated using the average weight method formula recommended by the International Electrotechnical Commission IEC. The maximum flow value qmax and the minimum pressure difference value △pmin appearing in the process control should be substituted into the formula calculation.
d) Select the appropriate valve diameter and Kv value according to the calculated Kv value. For straight-through single-seat quick opening and lubrication, generally when calculating the maximum Kv value, the opening of the valve should be less than 50%, and the smaller the opening, the better.
e) Estimate of noise. The estimation of valve noise is a more complicated problem. Nowadays, the formula researched and provided by Masorleilar1 is commonly used. This formula is more convenient to calculate and the calculation result is more accurate.
f) Calculation of unbalanced force and selection of actuator. By calculating the unbalanced force generated by the medium pressure difference on the valve core, considering the friction of each moving part of the valve, and finally selecting an appropriate amplification factor according to the process parameters and control requirements, the actuator can be selected.
g) According to the calculation results of the above steps, perform detailed valve configuration on the straight-through single-seat quick-opening valve. The main work is the selection of various parts and materials, and the selection of accessories.
