Biomedical Engineering Reference
In-Depth Information
Table 2.6 Types of flow sensors
Sensory type
Advantages
Disadvantages
Orifice
Low cost
Extensive industrial practice
High pressure loss
Plugging with slurries
Venture
Lower pressure loss than orifice
Slurries do not plug
High cost
Line under 15 cm
Flow nozzle
Good for slurry service
Intermediate pressure loss
Higher cost than orifice plate
Limited pipe sizes
Elbow meter
Low pressure loss
Very poor accuracy
Turbine
Wide range ability
Good accuracy
High cost
Strainer needed
Especially for slurries
Positive displacement
High range ability
Good accuracy
High pressure drop
Damaged by flow surge or solids
Table 2.7
(a) Mass flow rate, (b) Volume flow rate
a
a
g/s
kg/h
Tonne/d
lb/s
lb/h
Ton/d
2.205 9 10
-3
g/scq
1
3.6
0.08640
7.937
0.08503
6.124 9 10
-4
kg/h
0.2778
1
0.02400
2.205
0.02362
Tone/d
11.57
41.67
1
0.02551
91.86
0.9842
lb/s
453.6
1633
39.19
1
3600
38.57
2.788 9 10
-4
lb/h
0.1260
0.4536
0.01089
1
0.01071
Ton/d
11.76
42.34
1.016
0.02593
93.33
1
b
b
m
3
/s
ft
3
/s
ft
3
/h
l/h
ml/s
Gal/h
2.778 9 10
-7
9.810 9 10
-6
l/h
1
0.2778
0.2200
0.035316
3.6 9 10
6
10
-6
3.532 9 10
-5
Ml/s
1
0.7979
0.12714
m
3
/s
10
6
7.919 9 10
5
1.271 9 10
5
3.6
1
35.31
1.263 9 10
-6
4.460 9 10
-5
Gal/h
4.546
1.263
1
0.16056
ft
3
/s
1.019 9 10
5
2.832 9 10
4
2.242 9 10
4
0.02832
1
3600
ft
3
/h
7.865 9 10
-6
2.778 9 10
-4
28.316
7.8653
6.2282
1
a
SI unit g/s, Metric units kg/h, tonne/d, Imperial units lb/s, lb/h, ton/d
b
SI unit m
3
/s, Metric units l/h, ml/s, Imperial units gal/h, ft
3
/s, ft
3
/h
2.4.4 Level Sensor
In industry, usually vast quantities of liquids such as water, solvents, chemicals,
etc., are used in a number of industrial processes. Liquid level measurements are
made to ascertain the quality of liquid held in a container or vessel. The liquid
level affects both pressure and rate of flow in and out of the container and therefore
its measurement and/or control becomes quite important in a variety of processes
encountered in modern manufacturing plants. Level sensing is very much related
to
flow
sensing.
The
common
application
for
level
sensing
is
tank
level
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