Bailey Technical Catalogue - Safety Systems UK Ltd

SIZING GUIDELINES FOR AIR AND GAS DUTIESThe capacity sizing charts are for:1) Critical pressure drop sizing.2) Air.3) Temperature of 15°C.4) Units l/s.5) Standard rise at dead end setting.The following instructions will assist when the actualservice conditions differ from the above criteria.1) Critical Pressure DropThe air capacity charts are based on critical pressuredrop sizing. To achieve these flows, it is critical thatthe correct pipe sizes are used. Refer to page 70.2) Other GasesIf you wish to use the valve on other compatiblegases, the chart opposite can be used, however thecapacity will change depending on the specific gravityof the flowing gas. Divide the valve air capacity by SGto give the gas capacity(SG = specific gravity, relative to air = 1)3) Other TemperaturesIf the flowing temperature is not 15°C the chartcapacity will need to be divided by (T/288)where: T= flowing temperature °C + 273°K4) Useful Conversionsm 3 /h = l/s x 3.6CFM = l/s x 2.125) Non-Standard Rise at Dead EndFor a definition of rise at dead-end see Page 56.To calculate capacities at a different rise at dead endmultiply chart capacity by the below figures.Example:Chart air capacity = 100 l/sSG of gas = 0.8Gas capacity of valve will be100 ÷ 0.8 = 111.8 l/s (gas)Example:Chart air capacity = 100 l/sAir temperature = 50°C (T = 323°K)Actual Air capacity at temperature will be:100 ÷ 323/288 = 94.4 l/s (@ 50ºC)Example:Chart air capacity = l/sValve type Class TRequired rise at dead end 0.35 BargActual air capacity will become1000 x 0.54 = 540 l/sVALVE TYPERISE AT DEAD ENDClass T 0.35 Bar 0.7 Bar 1 Bar Note: Only the capacity shown0.54 0.77 1.0 at 1 Bar rise can be adjustedC10 5% 10% 15% 20% Note: Only the capacity shown0.25 0.5 0.75 1.0 at 20% rise can be adjustedBailey B20% (minimum 0.35 Bar)73