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| Question | Answer |
| Volume of a room | Width ft. X Height ft. X Length ft. = ft3r power |
| Square ft. | Length ft. X Width ft. |
| CFM per ton of cooling | 400 cfm per hour |
| Define CFM | Cubic Feet per Minute |
| Find CFM for 14,400 cubic ft. room needing 5 air changes per hour | 14,400cf / 60min = 240cfm 240cfm X 5 = 1,200cfm |
| What is the cross section of 10in round metal duct | Pi X Radius to the 2 power |
| Please excuse my dear aunt sally | Parentheses, exponents, multiplication, division, addition, subtraction |
| BTUH Sensible heat equation | 1.08 x cfm x Delta-T |
| BTUH Latent heat equation | .68 x cfm x delta - grains |
| Total heat equation | 4.5 x cm x delta - enthalpy |
| how to convert Watts to BTU's | W x 3.413 |
| Resistance in series | r1+ r2 +r3 = total r |
| resistance in parallel | 1 / 1/r1 +1/r2 +1/r3 = |
| capacitors in series | 1/ 1/c1 + 1/c2 + 1/c3 |
| hp2 = | hp2 = hp1 x (cfm2/cfm)3rd power |
| static pressure 2 = | sp2 = sp1 x (cfm2/cfm1)2 |
| revolutions per minute rpm | rpm2 = rpm1 x (cfm2/cfm1)1 |
| What are the 3 fan laws | revolution per minute 2 ()1 static pressure 2()2 horse power 2()3 |
| area of a rectangle | l x w |
| area of a circle | pi x radius 2nd power |
| diameter of a circle: | circumference / pi |
| air velocity | ft/min |
| air velocity equation | ft/min = cfm / duct area . |
| volume: | cfm = Cubic Feet per minute |
| static pressure is measured in | inch w.g. |
| What does delta mean | symbol triangle = difference |
| pi = | 3.14159 |
| h.g. stands for: | inches of mercury |
| atmosphere pressure at sea level | 14.7 psi |
| 1psi = ( )w.g. | 27.7612 w.g. |
| 1psi = how many in h.g: feet of water: in of w.: | h.g.29.92 33.9ft of water w.g.406.8 |
| turn btu sensible equation into cfm equation | btu = 1.08 x cfm x delta-t cfm = btu / 1.08 x delta-t |
| latent heat also refers to | humidity in the air |
| psychrometer unit of measurement | grains |
| convert 10in by 8in sq duct from sq into sq ft. | 10x8=1802ndp 180 x (1/144) = 1.25ft2ndp |
| velocity = | cfm / grill area in inch. that has been converted to sq ft. |
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