E1C10 09/14/2010
13:4:38 Page 435
The idea of using a nozzle as a flow meter was first proposed in 1891 by John Ripley
Freeman (1855–1932), an inspector and engineer employed by a fire insurance firm. His work
required tedious tests to quantify pressure losses in pipes, hoses, and fittings. He noted a
consistent relationship between pressure drop and flow rate through fire nozzles at higher
flow rates.
Example 10.3
The U-tube manometer filled with manometer fluid (of specific gravity S m ) of Figure 10.11 is used
to measure the pressure drop across an obstruction meter. A fluid having specific gravity S flows
through the meter. Determine a relationship between the meter flow rate and the measured
manometer deflection, H.
Relative pressure drop
0
Throat pressure tap
Upstream
pressure tap
Pipe flanges
Δ p
(Δ p) loss
p 2
p 2
p 1
d 0
d 0
d 1
2
3
r 1
Figure 10.9 The ASME long-radius nozzle with the associated flow pressure drop along its axis.
10.5 Pressure Differential Meters 435
13:4:38 Page 435
The idea of using a nozzle as a flow meter was first proposed in 1891 by John Ripley
Freeman (1855–1932), an inspector and engineer employed by a fire insurance firm. His work
required tedious tests to quantify pressure losses in pipes, hoses, and fittings. He noted a
consistent relationship between pressure drop and flow rate through fire nozzles at higher
flow rates.
Example 10.3
The U-tube manometer filled with manometer fluid (of specific gravity S m ) of Figure 10.11 is used
to measure the pressure drop across an obstruction meter. A fluid having specific gravity S flows
through the meter. Determine a relationship between the meter flow rate and the measured
manometer deflection, H.
Relative pressure drop
0
Throat pressure tap
Upstream
pressure tap
Pipe flanges
Δ p
(Δ p) loss
p 2
p 2
p 1
d 0
d 0
d 1
2
3
r 1
Figure 10.9 The ASME long-radius nozzle with the associated flow pressure drop along its axis.
10.5 Pressure Differential Meters 435