E1C10 09/14/2010
13:4:48 Page 463
10.3 What is the best estimate of the pipe flow rate for Problem 10.2, accounting for spatial variation and
if the systematic standard uncertainty of the instrument is 1% of the reading?
10.4 A manometer is used in a 5.1-cm water line to measure the pressure drop across a flow meter.
Mercury is used as the manometric fluid ðS ¼ 13:57Þ. If the manometer deflection is 10.16 cm Hg,
determine the pressure drop in N/m
2 .
10.5 A capacitance pressure transducer is used to measure the pressure differential across an orifice meter
located in a 25.4-cm pipe. For air flowing at 32
C, if the pressure differential is 69 kPa, find the
pressure head in cm H 2 O.
10.6 Estimate the expansion factor in measuring the flow of O 2 at 16
C through a 100-mm-i.d. pipe using
a square-edged orifice plate. The upstream pressure is 6.9 bar and the downstream pressure is 5.24
bar. The orifice diameter is 50 mm. R O 2 ¼ 260 J=kg-K.
10.7 The Reynolds number of a fluid flowing through a 5-cm-diameter, square-edged orifice plate meter
within a 15-cm pipe is 250,000. Find the discharge coefficient for flange taps.
10.8 At what flow rate of 20
C water through a 10-cm-i.d. pipe would the discharge coefficient of a
square-edged orifice plate ðb ¼ 0:4Þ become essentially independent of the Reynolds number?
10.9 Water (25
C) flows through a square-edged orifice plate ðb ¼ 0:5Þ housed within a 12-cm-i.d. pipe
at 50 L/s. Estimate the power required to overcome the orifice plate’s permanent pressure loss.
Assume flange taps.
10.10 Determine the flow rate of 38
C air through a 6-cm pipe if an ASME flow nozzle with a 3-cm throat
and throat taps are used, the pressure drop measured is 75 cm H 2 O, and the upstream pressure is
94.4 kPa abs.
10.11 A square-edged orifice ðb ¼ 0:5Þ is used to meter N 2 at 520
R through a 4-in. pipe. If the upstream
pressure is 20 psia and the downstream pressure is 15 psia, determine the flow rate through the pipe.
Flange taps are used. R N 2 ¼ 55:13 ft-lb/lbm10.12 Size a suitable orifice plate to meter the steady flow of water at 20
C flowing through a 38-cm pipe if
the nominal flow rate expected is 200 kg/s and the pressure drop must not exceed 15 cm Hg.
10.13 A cast venturi meter is to be used to meter the flow of 15
C water through a 10-cm pipe. For a
maximum differential pressure of 76 cm H 2 O and a nominal 0.5-m
3 /min flow rate, select a suitable
throat size.
10.14 For 120 ft
3 /m of 60
F water flowing through a 6-in. pipe, size a suitable orifice, venturi, and nozzle
flow meter if the maximum pressure drop cannot exceed 20 in. Hg. Estimate the permanent losses
associated with each meter. Compare the annual operating cost associated with each if the power
cost is $0.10/kW-h, a 60% efficient pump motor is used, and the meter is operated 6000 hr/year.
10.15 Estimate the flow rate of water through a 15-cm-i.d. pipe that contains an ASME long radius nozzle
ðb ¼ 0:6Þ if the pressure drop across the nozzle is 25.4 cm Hg. Water temperature is 27
C.
10.16 Locate a suitable position for a 10-cm square-edged orifice along a 2-m straight run of 20-cm i.d.
pipe if the orifice must be situated downstream but in-plane of a 90-degree elbow using ASME
codes.
10.17 An orifice ðb ¼ 0:4Þ is used as a sonic nozzle to meter a 40
C air flow in a 5-cm pipe. If upstream
pressure is 695 mm Hg abs and downstream pressure is 330 mm Hg abs, estimate the mass flow rate
through the meter. R ¼ 287 N-m/kg-K, k ¼ 1:4.
10.18 Compute the flow rate of 20
C air through a 0.5-m square-edged orifice plate that is situated in a
1.0-m-i.d. pipe. The pressure drop across the plate is 90 mm H 2 O, and upstream pressure is 2 atm.
Problems 463
13:4:48 Page 463
10.3 What is the best estimate of the pipe flow rate for Problem 10.2, accounting for spatial variation and
if the systematic standard uncertainty of the instrument is 1% of the reading?
10.4 A manometer is used in a 5.1-cm water line to measure the pressure drop across a flow meter.
Mercury is used as the manometric fluid ðS ¼ 13:57Þ. If the manometer deflection is 10.16 cm Hg,
determine the pressure drop in N/m
2 .
10.5 A capacitance pressure transducer is used to measure the pressure differential across an orifice meter
located in a 25.4-cm pipe. For air flowing at 32
C, if the pressure differential is 69 kPa, find the
pressure head in cm H 2 O.
10.6 Estimate the expansion factor in measuring the flow of O 2 at 16
C through a 100-mm-i.d. pipe using
a square-edged orifice plate. The upstream pressure is 6.9 bar and the downstream pressure is 5.24
bar. The orifice diameter is 50 mm. R O 2 ¼ 260 J=kg-K.
10.7 The Reynolds number of a fluid flowing through a 5-cm-diameter, square-edged orifice plate meter
within a 15-cm pipe is 250,000. Find the discharge coefficient for flange taps.
10.8 At what flow rate of 20
C water through a 10-cm-i.d. pipe would the discharge coefficient of a
square-edged orifice plate ðb ¼ 0:4Þ become essentially independent of the Reynolds number?
10.9 Water (25
C) flows through a square-edged orifice plate ðb ¼ 0:5Þ housed within a 12-cm-i.d. pipe
at 50 L/s. Estimate the power required to overcome the orifice plate’s permanent pressure loss.
Assume flange taps.
10.10 Determine the flow rate of 38
C air through a 6-cm pipe if an ASME flow nozzle with a 3-cm throat
and throat taps are used, the pressure drop measured is 75 cm H 2 O, and the upstream pressure is
94.4 kPa abs.
10.11 A square-edged orifice ðb ¼ 0:5Þ is used to meter N 2 at 520
R through a 4-in. pipe. If the upstream
pressure is 20 psia and the downstream pressure is 15 psia, determine the flow rate through the pipe.
Flange taps are used. R N 2 ¼ 55:13 ft-lb/lbm10.12 Size a suitable orifice plate to meter the steady flow of water at 20
C flowing through a 38-cm pipe if
the nominal flow rate expected is 200 kg/s and the pressure drop must not exceed 15 cm Hg.
10.13 A cast venturi meter is to be used to meter the flow of 15
C water through a 10-cm pipe. For a
maximum differential pressure of 76 cm H 2 O and a nominal 0.5-m
3 /min flow rate, select a suitable
throat size.
10.14 For 120 ft
3 /m of 60
F water flowing through a 6-in. pipe, size a suitable orifice, venturi, and nozzle
flow meter if the maximum pressure drop cannot exceed 20 in. Hg. Estimate the permanent losses
associated with each meter. Compare the annual operating cost associated with each if the power
cost is $0.10/kW-h, a 60% efficient pump motor is used, and the meter is operated 6000 hr/year.
10.15 Estimate the flow rate of water through a 15-cm-i.d. pipe that contains an ASME long radius nozzle
ðb ¼ 0:6Þ if the pressure drop across the nozzle is 25.4 cm Hg. Water temperature is 27
C.
10.16 Locate a suitable position for a 10-cm square-edged orifice along a 2-m straight run of 20-cm i.d.
pipe if the orifice must be situated downstream but in-plane of a 90-degree elbow using ASME
codes.
10.17 An orifice ðb ¼ 0:4Þ is used as a sonic nozzle to meter a 40
C air flow in a 5-cm pipe. If upstream
pressure is 695 mm Hg abs and downstream pressure is 330 mm Hg abs, estimate the mass flow rate
through the meter. R ¼ 287 N-m/kg-K, k ¼ 1:4.
10.18 Compute the flow rate of 20
C air through a 0.5-m square-edged orifice plate that is situated in a
1.0-m-i.d. pipe. The pressure drop across the plate is 90 mm H 2 O, and upstream pressure is 2 atm.
Problems 463