" But when along train of abuses and usurpations, pursing inviably the same object, evinces a design to reduce them under absolute despotism , it is their right, it is their duty to throw of such their goverment and provide new guards for their fucture security."

Duct Pressure တြက္နညိး ( အဲယားကြန္း ပညာ )

Calculation for Duct Static Pressure Loss တြင္သံုးထားေသာ Formula မ်ားကို ရွင္းၿပထားသည္။

Formula 1 သည္ 2001 ASHRAE Fundamentals Handbook (SI), Chapter 34, Equation No:11 အရ Air Flow ႏွင့္ Round Duct Cross Section Area ကို ေပး၍ Velocity (V) ကို တြက္ယူေသာ ASHRAE ပံုေသနည္းၿဖစ္သည္။ Air flow rate (l/s) ကို Liter per Second ၿဖင့္ေဖာ္ၿပေသာေၾကာင့္ 0.001 ႏွ့င့္ေၿမွာက္ထားသည္ကိုေတြ ့ရမည္။ သာမာန္ အထက္တန္းေက်ာင္းသံုး
Air flow rate = Round Duct Cross Section Area x Velocity ပင္ၿဖစ္သည္။
A = (3.14 x De2 )/4 သည္ Round Duct Cross Section Area ကို Round Duct၏ Diameter မွ တြက္ယူၿခင္းၿဖစ္သည္။ Rectangular duct ၿဖစ္ပါက ေအာက္ပါ Formula ကို အသံုးၿပဳ၍ Circular Equivalent diameter ၿဖစ္ေအာင္ေၿပာင္းထားၿခင္းၿဖစ္သည္။
ေအာက္ပါ Velocity မွ Velocity Pressure ကို ေၿပာင္းေသာ Formula ၿဖစ္သည္။
5.) For Absolute Roughness Factor

Ref: 2001 ASHRAE Fundamentals Handbook (SI), Chapter 34, Table No: 01




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