Convert the following reading of pressure to kPa, assuming that the ba

1.	Convert the following reading of pressure to kPa, assuming that the barometer reads 760mm Hg.(1) 90cm Hg gauge (2) 40cm Hg vacuum (3) 1.2m H2O gauge
Answer» Given that h = 760mm of Hg for P_atm P_atm= ρgh = 13.6 × 10³× 9.81 × 760/1000 = 101396.16 N/m² = 101396.16Pa = 101.39KPa ...(i) (a) 90cm Hg gauge P_gauge= ρgh = 13.6 × 10³ × 9.81 × 90/100 = 120.07KPa ...(ii) P_abs = P_atm + P_gauge = 101.39 + 120.07 Pabs = 221.46KPa .......ANS (b) 40cm Hg vacuum P_vacc = ρgh = 13.6 × 10³ × 9.81 × 40/100 = 53.366KPa ...(iii) Pabs = Patm – Pvacc = 101.39 – 53.366 Pabs = 48.02KPa .......ANS (c)1.2m Water gauge P_gauge = ρgh = 1000 × 9.81 × 1.2 = 11.772KPa ...(iv) P_abs = P_atm + P_gauge = 101.39 + 11.772 P_abs = 113.162KPa .......ANS

Convert the following reading of pressure to kPa, assuming that the barometer reads 760mm Hg.(1) 90cm Hg gauge (2) 40cm Hg vacuum (3) 1.2m H2O gauge

Answer»

Given that h = 760mm of Hg for P_atm

P_atm= ρgh = 13.6 × 10³× 9.81 × 760/1000 = 101396.16

N/m² = 101396.16Pa = 101.39KPa ...(i)

(a) 90cm Hg gauge

P_gauge= ρgh = 13.6 × 10³ × 9.81 × 90/100 = 120.07KPa ...(ii)

P_abs = P_atm + P_gauge = 101.39 + 120.07

Pabs = 221.46KPa .......ANS

(b) 40cm Hg vacuum

P_vacc = ρgh = 13.6 × 10³ × 9.81 × 40/100 = 53.366KPa ...(iii)

Pabs = Patm – Pvacc

= 101.39 – 53.366

Pabs = 48.02KPa .......ANS

P_gauge = ρgh = 1000 × 9.81 × 1.2 = 11.772KPa ...(iv)

P_abs = P_atm + P_gauge

= 101.39 + 11.772

P_abs = 113.162KPa .......ANS

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