Chapter 4 : Measures Of Pressure

Example 4.1 Page No : 85

In [2]:
import math 

			
# Variables :
p = 5.;			#kg/cm**2
print ("Gauge units : ");

# Calculations and Results
print "Pressure Intensity in kg/m**2 : ",(p/10**-4)
g = 9.81;			#gravity consmath.tant
print "Pressure Intensity in N/m**2 : ",(p*g/10**-4)
print "Pressure Intensity in Pa : ",(p*g/10**-4)
print "Pressure Intensity in kPa : ",p*g/10**3/10**-4
print "Pressure Intensity in MPa : ",p*g/10**6/10**-4
print ("In terms of head : ");
w = 1000.;			#kg/m**3 for water
h = p*10**4/w;			#meter of water
print "Pressure is  : ",(h)," meter of water."
w = 13.6*1000;			#kg/m**3 for mercury
h = p*10**4/w;			#meter of mercury
print "Pressure is  : ",(h)," meter of mercury."
print ("Absolute units : ");
Patm = 760.;			#mm of mercury
Patm = 760*13.6/1000;			#m of water
Patm = Patm*1000.;			#kg/m**2
Pabs = p+Patm;			#kg/m**2
print "Absolute pressure in kg/m**2 : ",Pabs
print "Absolute pressure in kg/cm**2 : ",Pabs*10**4
print "Absolute pressure in N/m**2 : ",Pabs*10**4*g
print "Absolute pressure in Pa : ",Pabs*10**4*g
print "Absolute pressure in kPa : ",Pabs*10**5/10**3
print "Absolute pressure in MPa : ",Pabs*10**5/10**6
h1 = p*10.**4/w;			#meter of water
h2 = p*10.**4/1000;			#meter of water
h = h1+h2;			#			#meter of water
print "Absolute pressure head in terms of water in meter : ",h
w = 13.6*1000;			#kg/m**3 for mercury
h = p*10**4/w+760./1000;			#meter of mercury
print "Absolute pressure head in terms of mercury in meter : %.3f"%h

# note : rounding off error

Gauge units : 
Pressure Intensity in kg/m**2 :  50000.0
Pressure Intensity in N/m**2 :  490500.0
Pressure Intensity in Pa :  490500.0
Pressure Intensity in kPa :  490.5
Pressure Intensity in MPa :  0.4905
In terms of head : 
Pressure is  :  50.0  meter of water.
Pressure is  :  3.67647058824  meter of mercury.
Absolute units : 
Absolute pressure in kg/m**2 :  10341.0
Absolute pressure in kg/cm**2 :  103410000.0
Absolute pressure in N/m**2 :  1014452100.0
Absolute pressure in Pa :  1014452100.0
Absolute pressure in kPa :  1034100.0
Absolute pressure in MPa :  1034.1
Absolute pressure head in terms of water in meter :  53.6764705882
Absolute pressure head in terms of mercury in meter : 4.436

Example 4.2 Page No : 88

In [3]:
import math 
		
# Variables :
w = 1000.;			#kg/m**3
h = 50./1000;			#m

# Calculations and Results
p = w*h;			#kg/m**2
p = p*9.81;			#N/m**2 or Pa
print "Pressure Intensity in Pa : ",p
alfa = 30.;			#degree
h = 50;			#mm
l = h/math.sin(math.radians(alfa));			#mm
print "Reading in tube in mm : ",l

Pressure Intensity in Pa :  490.5
Reading in tube in mm :  100.0

Example 4.3 Page No : 89

In [3]:
import math 
			
# Variables :
S1 = 13.6;			#sp. gravity of mercury
S2 = 1.;			#sp. gravity of water
H1 = 5.;			#m

# Calculations and Results
H2 = S1*H1/S2;			#m
print "(i) Pressure is ",(H2)," meter of water."

S2 = 0.79;			#sp. gravity of kerpsene
H1 = 5;			#m
H2 = S1*H1/S2;			#m
print "(ii) Pressure is ",round(H2,3)," meter of kerosene."

S2 = 1.7;			#sp. gravity of fluid
H1 = 5;			#m
H2 = S1*H1/S2;			#m
print "(iii) Pressure is ",(H2)," meter of fluid."

(i) Pressure is  68.0  meter of water.
(ii) Pressure is  86.076  meter of kerosene.
(iii) Pressure is  40.0  meter of fluid.

Example 4.4 Page No : 95

In [4]:
			
# Variables :
S = 0.9;			#sp. gravity of liquid
Sm = 13.6;			#sp. gravity of mercury
S1 = Sm/S;			#sp. gravity

# Calculations
w = S*9.81;			#kN/m**3
h2 = 500./1000;			#m
h1 = 300./1000;			#m
a_BY_A = 1./80;			#ratio of area
pa = w*(h2*((S1-1)*a_BY_A+S1)-h1);			#kPa

# Results
print "Pressure in the pipe in kPa: %.3f"%pa

Pressure in the pipe in kPa: 64.838

Example 4.5 Page No : 96

In [5]:
import math 
			
# Variables :
S1 = 1.2;			#sp. gravity
S2 = 13.6;			#sp. gravity
w = 1000.;			#kg/m**3

# Calculations
h2 = 50./1000;			#m
h1 = 200./1000;			#m
pa = w*(S2*h1-S1*h2);			#kg/m**2

# Results
print "Pressure in the pipe in kg/m**2: ",pa
print "Pressure in the pipe in Pa: ",pa*9.81

Pressure in the pipe in kg/m**2:  2660.0
Pressure in the pipe in Pa:  26094.6

Example 4.6 Page No : 97

In [6]:
			
# Variables :
S = 1.;			#sp. gravity
w = 1000.;			#kg/m**3
h2 = 50./1000;			#m
h1 = 200./1000;			#m

# Calculations
pa = w*S*(h1-h2);			#kg/m**2

# Results
print "Pressure in the pipe in kg/m**2: ",pa
print "Pressure in the pipe in Pa: ",pa*9.81

Pressure in the pipe in kg/m**2:  150.0
Pressure in the pipe in Pa:  1471.5

Example 4.7 Page No : 97

In [7]:
import math 
			
# Variables :
S1 = 0.005;			#sp. gravity
S2 = 1.;			#sp. gravity
Patm = 1.014*10**5;			#Pa
h = 50./1000;			#m
w = 1000.;			#kg/m**3

# Calculations
pa = -w*S2*h;			#kg/m**2
Pabs = pa*9.81+Patm;			#

# Results
print "Pressure intensity of gas in Pa(Vaccum): ",abs(pa*9.81)
print "Absolute pressure in the pipe in Pa: ",Pabs

Pressure intensity of gas in Pa(Vaccum):  490.5
Absolute pressure in the pipe in Pa:  100909.5

Example 4.8 Page No : 100

In [8]:
			
# Variables :
S1 = 0.9;			#sp. gravity
S2 = 13.6;			#sp. gravity
h1 = 12.5/100;			#m

# Calculations and Results
P_AB = h1*(S2-S1);			#meter of water
print "Difference in pressure head at the points A & B is ",(P_AB)," meter of water"

w = 1000;			#kg/m**3
P_diff = P_AB*w*9.81;			#Pa or Nm**2
print "In terms A pressure entirely, the difference of pressure in N/m**2 : ",P_diff

Difference in pressure head at the points A & B is  1.5875  meter of water
In terms A pressure entirely, the difference of pressure in N/m**2 :  15573.375

Example 4.9 Page No : 100

In [9]:
			
# Variables :
S1 = 1.;			#sp. gravity
S2 = 13.6;			#sp. gravity
h1 = 120./1000;			#m

# Calculations and Results
P_diff = h1*(S2-S1);			#meter of water
print "Difference in pressure head is ",(P_diff)," meter of water"
w = 1000;			#kg/m**3
P_diff = P_diff*w*9.81;			#Pa or Nm**2
print "In terms of pressure intensity, the difference of pressure in N/m**2 : ",P_diff

Difference in pressure head is  1.512  meter of water
In terms of pressure intensity, the difference of pressure in N/m**2 :  14832.72

Example 4.10 Page No : 103

In [10]:
import math 

			
# Variables :
S1 = 0.81;			#sp. gravity
S2 = 1.2;			#sp. gravity
S3 = 13.6;			#sp. gravity
h3 = 200./1000;			#m
h2 = 50./1000;			#m
h1 = 100./1000;			#m
w = 1000.;			#kg/m**3

# Calculations
pAB = ((h1*(S2-S1)+h2*(S3-S1)-h3*S1))*w;			#Kg/m**2

# Results
print "Pressure difference between the two vessel in kg/m**2: ",pAB

Pressure difference between the two vessel in kg/m**2:  516.5

Example 4.11 Page No : 104

In [11]:
import math 
		
# Variables :
S1 = 1.9;			#sp. gravity
S2 = 1.2;			#sp. gravity
S3 = 0.79;			#sp. gravity
h2 = 545./1000;			#m
h1 = 750./1000;			#m
h3 = h1-h2;			#m
w = 1000*9.81;			#N/m**3

# Calculations
pAB = (h1*S1-h2*S2-h3*S3)*w;			#N/m**2

# Results
print "Pressure difference between the two vessel in N/m**2: ",pAB

Pressure difference between the two vessel in N/m**2:  5974.7805

Example 4.12 Page No : 105

In [12]:
			
# Variables :
S1 = 0.005;			#sp. gravity
S2 = 0.79;			#sp. gravity
S3 = 13.6;			#sp. gravity
h = 30./1000;			#m
w = 1000*9.81;			#N/m**3

# Calculations
pAB = h*(S3-S2)*w;			#N/m**2

# Results
print "Pressure difference between the two vessel in N/m**2: ",pAB

Pressure difference between the two vessel in N/m**2:  3769.983

Example 4.13 Page No : 105

In [14]:
import math 

			
# Variables :
S1 = 1.25;			#sp. gravity
S2 = 1.05;			#sp. gravity
S3 = 0.79;			#sp. gravity
h = 30./1000;			#m
w = 1000.;			#kg/m**3

# Calculations
#pA = pB
h = (0.15*w*S2-S1*w*0.15)/(S3*w-w*S2);			#m
h = h*1000;			#mm

# Results
print "Reading of manometer in mm : %.f"%h

Reading of manometer in mm : 115

Example 4.14 Page No : 106

In [15]:
import math 
			
# Variables :
S1 = 1.;			#sp. gravity of water
S2 = 1.;			#sp. gravity of water
S3 = 0.9;			#sp. gravity of oil
h3 = 100./1000;			#meter
w = 9.81*1000;			#N/m**3

# Calculations
pAB = w*(h3-h3*S3);			#N/m**2

# Results
print "Difference of pressure in N/m**2 or Pa : ",pAB

Difference of pressure in N/m**2 or Pa :  98.1