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KUNKLE VALVE SIZING GUIDE
See below for Kunkle Safety and Relief Valve sizing and selection guides for use in Steam, Air and Gas, and Liquids. Expand each section below for a detailed look at gas flow conversions and formulas, air and gas temperature correction factors, physical properties, and steam super heat correction.
Sizing and Selection
- Sizing and selection for Steam
- To obtain lb/h for sizing, divide BTU (max. firing rate) by 1000.
- To obtain kg/h for sizing, divide KW by 0.6461.
- Sizing and selection for Liquid
- Liquid valves must be sized closely to actual flow; oversizing causes "chatter," and under-sizing causes high pressure.
- Liquid relief valves are normally capacity rated at 25% overpressure. Refer to the capacity correction tables to f10% overpressure. ASME Section I and VIII and XIII-UV Liquid Valves are rated at 10% overpressure.
- Sizing and selection for Air/Gas
- Valves for cold or cryogenic temperatures (below -20F (-29) must be made from bronze, brass, or stainless steel to avoid the brittleness found in other materials at these temperatures. Many valves are offered with cryogenic materials as an option/extra.
If flow is expressed in actual volume, such as CFM (cubic feet per minute) or ACFM (actual CFM) as is often done for compressors, where the flow is described as displacement or swept volume, the flow may be converted to SCFM as follows (or from flow expressed in m3/h to Nm3/h).
Conversions from one volumetric flow rate to another or to weight flow (and vice versa) may only be done when the volumetric flow is expressed in the standard conditions shown above. If flows are expressed at temperature or pressure bases that differ from those listed, above, they must first be converted to the standard base.
Conversion Formulas
Degrees Fahrenheit (°F)Degrees Celsius (°C)F + 459.67 = R (Rankine)(F - 32) x 0.556 = C (Celsius)C + 273.15 = K (Kelvin)(C x 1.8) + 32 = F (Fahrenheit)
- Temperature °FTemperature °CTemperature Correction0-181.06210-121.05120-71.04130-11.0304041.02050101.00960161.00070210.99180270.98190320.972100380.964120490.947140600.931160710.916180820.902200930.8882201040.8742401160.8622601270.8492801380.8383001490.8283201600.8173401710.8063601820.7963801930.7874002040.7784202160.7694402270.7604602380.7524802490.7445002600.7375502880.7186003160.7016503430.6857003710.6697503990.656
*For temperatures other than 60°F (15.6°C) at valve inlet, multiply SCFM by Tc.
Gas or VaporM
Molecular Weightk
Specific Heat RatioC
Gas ConstantAir28.971.40356Ammonia, Anhydrous17.031.31348Butane-n (Normal Butane)58.121.09326Carbon Dioxide44.011.29346Carbon Monoxide28.011.40356Dowtherm A165.001.05321Dowtherm E147.001.00315Ethane30.071.19336Ethylene (Ethene)28.051.24341Helium4.001.67378Hydrogen2.021.41357Methane16.041.31348Natural Gas (specific gravity = 0.60)17.401.27344Nitrogen28.011.40356Octane114.231.05321Oxygen32.001.40356Propane44.101.13330Steam18.021.31348
For capacitates of super-heated steam, multiply saturated steam capacity by correction factor below.
Steam Super Heat Correction Factor, K5 | Steam Temperature between 340°F [171°C] to 540°F [282°C]
Set Pressure Saturated Steam Temp Steam Temperature in °F [°C] psig [barg] °F [°C] 340 [171] 360 [182] 380 [193] 400 [204] 420 [216] 440 [227] 460 [238] 480 [249] 500 [260] 520 [271] 540 [282] 15 [1.0] 250 [121.1] 0.99 0.99 0.98 0.98 0.97 0.96 0.95 0.94 0.93 0.92 0.91 20 [1.4] 259 [126.1] 0.99 0.99 0.98 0.98 0.97 0.96 0.95 0.94 0.93 0.92 0.91 40 [2.8] 287 [141.7] 1.00 0.99 0.99 0.98 0.97 0.96 0.95 0.94 0.93 0.92 0.91 60 [4.1] 308 [153.4] 1.00 0.99 0.98 0.98 0.97 0.96 0.95 0.94 0.93 0.92 0.91 80 [5.5] 324 [162.2] 1.00 1.00 0.99 0.99 0.98 0.97 0.96 0.94 0.93 0.92 0.91 100 [6.9] 338 [170.9] 1.00 1.00 0.99 0.98 0.97 0.96 0.95 0.94 0.93 0.92 120 [8.2] 350 [177.0] 1.00 1.00 0.99 0.98 0.97 0.96 0.95 0.94 0.93 0.92 140 [9.6] 361 [182.6] 1.00 1.00 0.99 0.98 0.96 0.95 0.94 0.93 0.92 160 [11.0] 371 [188.6] 1.00 0.99 0.98 0.97 0.95 0.94 0.93 0.92 180 [12.8] 380 [193.0] 1.00 0.99 0.98 0.97 0.96 0.95 0.93 0.92 200 [13.7] 388 [198.0] 1.00 0.99 0.99 0.97 0.96 0.95 0.93 0.92 220 [15.1] 395 [201.0] 1.00 1.00 0.99 0.98 0.96 0.95 0.94 0.93 240 [16.5] 403 [205.7] 1.00 0.99 0.98 0.97 0.95 0.94 0.93 260 [17.9] 409 [209.4] 1.00 0.99 0.98 0.97 0.96 0.94 0.93 280 [19.2] 416 [213.3] 1.00 1.00 0.99 0.97 0.96 0.95 0.93 300 [20.6] 422 [217.0] 1.00 0.99 0.98 0.96 0.95 0.93 350 [24.1] 436 [224.3] 1.00 1.00 0.99 0.97 0.96 0.94 400 [27.5] 448 [231.0] 1.00 0.99 0.98 0.96 0.95 450 [31.0] 460 [238.0] 1.00 0.99 0.97 0.96 500 [34.4] 470 [243.0] 1.00 0.99 0.98 0.96 550 [37.9] 480 [249.0] 1.00 0.99 0.97 600 [41.3] 489 [258.0] 1.00 0.99 0.98 650 [44.8] 497 [263.3] 1.00 0.99 700 [48.2] 506 [267.7] 1.00 0.99 750 [51.7] 513 [271.3] 1.00 1.00 800 [55.2] 520 [275.0] 1.00 850 [58.6] 527 [249.0] 1.00 900 [62.1] 533 [278.4] 1.00 950 [65.5] 540 [282.2] 1000 [69.0] 546 [285.6]
Steam Super Heat Correction Factor, K5 | Steam Temperature between 560°F [293°C] to 760°F [404°C]
Set Pressure Saturated Steam Temp Steam Temperature in °F [°C] psig [barg] °F [°C] 560 [293] 580 [304] 600 [316] 620 [327] 640 [338] 660 [349] 680 [360] 700 [371] 720 [382] 740 [393] 760 [404] 15 [1.0] 250 [121.1] 0.90 0.89 0.88 0.87 0.86 0.86 0.85 0.84 0.83 0.83 0.82 20 [1.4] 259 [126.1] 0.90 0.89 0.88 0.87 0.86 0.86 0.85 0.84 0.83 0.83 0.82 40 [2.8] 287 [141.7] 0.90 0.89 0.88 0.87 0.87 0.86 0.85 0.84 0.84 0.83 0.82 60 [4.1] 308 [153.4] 0.90 0.89 0.88 0.87 0.87 0.86 0.85 0.84 0.84 0.83 0.82 80 [5.5] 324 [162.2] 0.90 0.89 0.89 0.88 0.87 0.86 0.85 0.84 0.84 0.83 0.82 100 [6.9] 338 [170.9] 0.91 0.90 0.89 0.88 0.87 0.86 0.85 0.85 0.84 0.83 0.82 120 [8.2] 350 [177.0] 0.91 0.90 0.89 0.88 0.87 0.86 0.85 0.85 0.84 0.83 0.82 140 [9.6] 361 [182.6] 0.91 0.90 0.89 0.88 0.87 0.86 0.85 0.85 0.84 0.83 0.82 160 [11.0] 371 [188.6] 0.91 0.90 0.89 0.88 0.87 0.86 0.86 0.85 0.84 0.83 0.82 180 [12.8] 380 [193.0] 0.91 0.90 0.89 0.88 0.87 0.86 0.86 0.85 0.84 0.83 0.82 200 [13.7] 388 [198.0] 0.91 0.90 0.89 0.88 0.87 0.86 0.86 0.85 0.84 0.83 0.83 220 [15.1] 395 [201.0] 0.92 0.91 0.90 0.89 0.88 0.87 0.86 0.85 0.84 0.84 0.83 240 [16.5] 403 [205.7] 0.92 0.91 0.90 0.89 0.88 0.87 0.86 0.85 0.84 0.84 0.83 260 [17.9] 409 [209.4] 0.92 0.91 0.90 0.89 0.88 0.87 0.86 0.85 0.85 0.84 0.83 280 [19.2] 416 [213.3] 0.92 0.91 0.90 0.89 0.88 0.87 0.86 0.85 0.85 0.84 0.83 300 [20.6] 422 [217.0] 0.92 0.91 0.90 0.89 0.88 0.87 0.86 0.86 0.85 0.84 0.83 350 [24.1] 436 [224.3] 0.93 0.92 0.91 0.90 0.89 0.88 0.87 0.86 0.85 0.84 0.83 400 [27.5] 448 [231.0] 0.93 0.92 0.91 0.90 0.89 0.88 0.87 0.86 0.85 0.84 0.84 450 [31.0] 460 [238.0] 0.94 0.93 0.92 0.91 0.89 0.88 0.87 0.86 0.86 0.85 0.84 500 [34.4] 470 [243.0] 0.94 0.93 0.92 0.91 0.90 0.89 0.88 0.87 0.86 0.85 0.84 550 [37.9] 480 [249.0] 0.95 0.94 0.92 0.91 0.90 0.89 0.88 0.87 0.86 0.85 0.84 600 [41.3] 489 [258.0] 0.96 0.94 0.93 0.92 0.90 0.89 0.88 0.87 0.86 0.85 0.84 650 [44.8] 497 [263.3] 0.97 0.95 0.94 0.92 0.91 0.90 0.89 0.87 0.86 0.86 0.85 700 [48.2] 506 [267.7] 0.97 0.96 0.94 0.93 0.91 0.90 0.89 0.88 0.87 0.86 0.85 750 [51.7] 513 [271.3] 0.98 0.96 0.95 0.93 0.92 0.90 0.89 0.88 0.87 0.86 0.85 800 [55.2] 520 [275.0] 0.99 0.97 0.95 0.94 0.92 0.91 0.90 0.88 0.87 0.86 0.85 850 [58.6] 527 [249.0] 0.99 0.98 0.96 0.94 0.93 0.92 0.90 0.89 0.88 0.87 0.86 900 [62.1] 533 [278.4] 1.00 0.99 0.97 0.95 0.93 0.92 0.90 0.89 0.88 0.87 0.86 950 [65.5] 540 [282.2] 1.00 0.99 0.97 0.95 0.94 0.92 0.91 0.89 0.88 0.87 0.86 1000 [69.0] 546 [285.6] 1.00 0.99 0.98 0.96 0.94 0.93 0.91 0.90 0.89 0.87 0.86