Chapter 12:Measurement of Non-Electrical Quantities¶

Example 12.1,Page No:600¶

In [1]:
import math

#variable declaration
Gf  = 2;                                 #guage factor
a   = 100*10**6;                         #stress in N/m**2
E   = 200*10**9;                         #elasticity of steel in N/m**2

#calculation
st     = (a/float(E));                        #strain
x      = Gf*st;                              # change in guage resistance
p      = (x)*100;                            #percentage change in resistance in %

#result
print"percentage change in resistance %1.1f"%p,"%";

percentage change in resistance 0.1 %


Example 12.4,Page No:631¶

In [2]:
import math

#variable declaration
D1   = 200*10**-3;               # inlet horizontal venturimeter in m
D2   = 100*10**-3;               #throat horizontal enturimeter in m
h    = 220*10**-3;               #pressure in m
Cd   = 0.98;                     #coefficient of discharge
phg  = 13.6;                     #specific gravity of mercury
p    = 1000;                     #density of water in kg/m**3
g    = 9.81;                     #gravitational constant
pw   = 1;                        #density of water in kg/m**3
w    = 9.81;

#calculation
x    = (g)*(h)*(phg-pw)*1000;            #differential pressure  head in N/m**2
a    = 1-((D2/float(D1))**4);            #velocity approach factor
M    = 1/(float(math.sqrt(a)));           #velocity of approach
b    = math.sqrt(((2*g)/(float(w*p)))*x);
A2   = (math.pi/float(4))*((D2)**2);      #area in m**2
Q    = Cd*M*A2*(b);                       #discharge through venturimeter in m**3/s

#result
print'water flow rate %3.4f'%Q,'m**3/s';

water flow rate 0.0586 m**3/s


Example 12.5,Page No:631¶

In [3]:
import math

#variable declaration
D1    = 400*10**-3;                    #diameter at inlet in m
D2    = 200*10**-3;                    #diameter at throat in m
y     = 50*10**-3;                     #reading of differential manometer in m
Shl   = 13.6;                          #specific gravity of mercury in U-tube
Sp    = 0.7;                           #specific gravity of oil in U-tube
h     = 0.92;

#bernoulli's equation
#p1/w +z1+V1**2=p2/w +z2+V2**2
#solving we get h+(V1**2/2*g)-(V2**2/2*g)=0
# calculations

A1    =  (math.pi/float(4))*(D1**2);                   #area in m**2
A2    =  (math.pi/4)*(D2**2);                          #area in m**2
a     =  A2/float(A1);                                 #ratio of areas
#V1 = a*V2;
#h+(V1**2/2*g)*(1-(1/4))=0
V2    =  math.sqrt((2*g*h)/(float(1-((a)**2))));
Q     =  A2*V2;                                         #rate of oil flow in m**3/s

#result
print'rate of flow of oil %f'%Q,'m**3/s';

rate of flow of oil 0.137850 m**3/s


Example 12.6,Page No:633¶

In [4]:
import math

#variable declaration
Q    = 0.015;                          #rate of flow in m**3/s
D0   = 100*10**-3;                     #diameter orifice in m
D1   = 200*10**-3;                     #diameter of pipe in m
Cc   =  0.6;                           #coefficient of contraction
Cd   =  0.6;                           #coefficient  of discharge
E    = 1;                              #thermal expansion factor
g    = 9.81;                           #gravitational constant
w    = 9810;

#calculations
A0 =  ((math.pi)/float(4))*(D0**2);               #area in m**2
A1 =  ((math.pi)/float(4))*(D1**2);               #area in m**2
a  =  (Cc*A0)/(float(A1));
M  =  math.sqrt(1-((a)**2));
K  =  Cd/float(M);
x  =  ((Q/float(K*E*A0))**2);
dp = (x*w/float(2*g));                          #difference in pressure head in N/m**2

#result

difference in pressure head 4952.073 N/m**2


Example:12.7,Page No:633¶

In [5]:
import math

#variable declaration
C0  = 0.6;                    #coefficient of orifice
Cv  = 0.97;                   #coefficient of discharge
Qv  =  1.2;                   #flow rate in m**3/s

#calculations
Q0  = (C0/Cv)*Qv;             #discharge through the orifice in m**3/s

#result
print'discharge through the orifice %3.3f'%Q0,'m**3/s'

discharge through the orifice 0.742 m**3/s


Example:12.8,Page No:634¶

In [6]:
import math

#variable declaration
Shl = 13.6;                #specific gravity of mercury
Sl  = 1.025;               #specific gravity of sea water
y   = 200*10**-3;          #reading in m
g   = 9.81;                #constant

#calculation
x     = Shl/float(Sl);

velocity of submarine 25.0 km/h