1. 15.0 Math Review 14.5 Using Basic Formulas

2. Converting Units Converting 6 inches of Mercury into Inches of Water Inches of Mercury are multiplied by 13.6 to get inches of water 6” of Mercury = 13.6 x 6 = 81.6 inches of water Note: 81.6” ÷ 12” = feet of water = 6.8’

3. Converting Units Convert 82 Inches of Water to Inches of Mercury Inches of water are multiplied by 0.0735 to get Inches of Mercury 82” x 0.0735 = 6.027” of Mercury

4. Converting Units LPS x 0.472 = CFMCFM x 2.12 = LPS HP x 0.746 = Kilowatts1Watt = 3.412 Btu/h Ft of H 2 O x 0.433 = psipsi x 2.31 = Ft of H 2 O [F 0 – 32] x 5/9 = C 0 [C 0 x 9/5] + 32 = F 0 h = P psia ÷ 0.433P psia = psi + 14.7 Tons of Refrigeration = HP x 4.716 Tons of Refrigeration = BTU/minute x 200 Note: HP x 4.716 = Btu/minute x 200

5. Converting Units Square inches are divided by 144 to get square feet 72 in 2 = ? Ft 2 72 ÷ 144 = 0.5 Ft 2 Note: Ft 2 x 144 = in 2

6. Using Equations 3 2 600 400 = 600 400 = 2 3 = 3 x 200 2 x 200

7. Using Equations Fan Law CFM new CFM old RPM old RPM new = CFM new CFM old = RPM new RPM old

8. Using Equations 3 2 600 400 = 600 400 x 2 3 = x x 3 2 = 600

9. Using Equations Fan Law CFM new CFM old RPM old RPM new = CFM new CFM old = RPM new RPM old x

10. Using Equations Fan Law CFM new CFM old RPM old RPM new = CFM new CFM old ? RPM new RPM old = 875 = 555 = 1100

11. Using Equations Fan Law 875 5551100 RPM new = CFM new CFM old ? RPM new RPM old = 875 = 555 = 1100

12. Using Equations Fan Law 875 5551100 RPM new = 875 555 1100 = x RPM new = 1734.23

13. Using Equations Fan Law CFM new CFM old RPM old RPM new = CFM new CFM old = RPM new RPM old x

14. Percent of Design If we measured 147 CFM of air and the design value wanted was 150 CFM: How would that be converted to % of design? Number Found ÷ Design Value x 100 = % of Design 147÷ 150 x 100 = % of Design 98%

15. Percent of Design If we measured 171 CFM of air and the design value wanted was 150 CFM: How would that be converted to % of design? Number Found ÷ Design Value x 100 = % of Design 171÷ 150 x 100 = % of Design 114%

16. Averaging Add up the numbers you have and divide that answer by the total of the numbers you have. Example for the number of people at work: Monday = 15 Tuesday = 17 Wednesday = 18 Thursday = 18 Friday = 12 15 + 17 + 18 + 18 + 12 = 80 80 ÷ 5 = 16

17. Averaging Monday $7.80 Tuesday $6.72 Wednesday $7.83 Thursday $10.57 Friday $9.56 Don’s Average Lunch Cost For The Week + $42.48

18. Averaging Monday $7.80 Tuesday $6.72 Wednesday $7.83 Thursday $10.57 Friday $9.56 Don’s Average Lunch Cost For The Week 1234512345 $42.48 42.48 ÷ 5 = Average = 8.496 or $8.50

19. Traverse Readings/Measurements abcd 1340373320394 2366333352391 3362336365331 Airflow measured in feet per minute (fpm) for 8” round duct.

20. Traverse Readings/Measurements abcd 1340373320394 2366333352391 3362336365331 1068

21. Traverse Readings/Measurements abcd 1340373320394 2366333352391 3362336365331 1068 + 1042

22. Traverse Readings/Measurements abcd 1340373320394 2366333352391 3362336365331 1068 + 1042 + 1037

23. Traverse Readings/Measurements abcd 1340373320394 2366333352391 3362336365331 1068 + 1042 + 1037 + 1116

24. Traverse Readings/Measurements abcd 1340373320394 2366333352391 3362336365331 1068 + 1042 + 1037 + 1116 = 4263 4263 ÷ 12 = 355.25 or 355 fpm