The safety valve for the admission of any working environment is obliged to be selected on the type so that pressure in the Wednesday protected by it did not exceed admissible. How to calculate the valve?
Instruction
1. Its flow capacity is considered one of key characteristics of operation of the control valve. She says in m3/h and depends on the speed with which liquid passes through the valve. And this speed, in turn, is regulated by temperature of the passing liquid and pipeline pressure.
2. The main size considered at valve operation is metric characteristic which in Europe is designated by the letters Kv. It is defined as the amount (m3) of any liquid at temperature of equal 20 degrees Celsius passing in one hour through full valve throat when accounting differential pressure on the valve in 1 bar (that is 1 kg/cm2). In America it is accepted to use the designation Cv. It is counted as liquid stream at temperature of 60 degrees Fahrenheit in US of gallons/min. when accounting differential pressure on the valve in 1 lb/hr. Coefficients correspond as follows: Cv = 1.16 Kv. This value is always specified in technical data sheet of the valve and is one of criteria for its choice.
3. Flow capacity is calculated by formula: where Q - liquid consumption in m³/часДельта r – is defined as p1 - p2 and designates differential pressure on the valve. The specified formula it is applied generally for liquids. Formulas for measurement of flow capacity of gases. Also the program for calculation and selection of water safety valves can be found here: http://www.pressair.ru/upl1.html. If you are not especially strong in mathematical calculations, it is better to trust in opportunities of worldwide network.
4. Reliability and safety of work of any passing system depends on the correct calculation and selection of the corresponding valve. Therefore it is necessary to choose only qualitative products of well-known companies, and for installation, replacement and repair to address experts.