# Chapter 15 : Positive-displacement Machines¶

### Example 15.2.1 page no : 490¶

In [1]:
import math
#initialisation of variables
B= 34. 			#ft
z= 6. 			#ft
g= 32.2 			#ft/sec**2
d= 6. 			#in
do= 2. 			#in
l= 6. 			#ft
l1= 0.04

#CALCULATIONS
s= math.sqrt((g*do**2*(B-6-z))/(l*d**2*(d/12)))
s1= s*60/(2*math.pi)
hf= l1*(l/(2*g*(do/12)))*(d**2*s*d/(12*do**2))**2

#RESULTS
print  ' maximum friction head= %.2f ft'%(hf)

 maximum friction head= 11.88 ft


### Example 15.3.1 pageno : 493¶

In [2]:
import math
#initialisation of variables
f= 0.01
l= 160. 			#ft
g= 32.2 			#ft/sec**2
d1= 10. 			#in
d2= 4.5 			#in
w= 62.3 			#lbf/ft**3
v= 60. 			#rev/min

#CALCULATIONS
hf= (4*f*l/(2*g*(d2/12)))*(d1**2*3*2*math.pi/(4*d2**2))**2
h1= (2*hf/3)
r= (d1**2*3/(d2**2*2))
h= (4*f*l*r**2/(2*g*(d2/12)))
W= (math.pi*d1**2*1.5*w*10*v/(4*1444))
hp= W*(h1-h)/33000.

#RESULTS
print  ' Horse power saved= %.1f h.p'%(hp)

 Horse power saved= 7.5 h.p


### Example 15.4.1 page no : 496¶

In [3]:
import math
#initialisation of variables
d= 12. 			#in
n= 3.
l= 24. 			#in
w= 1100. 			#gallons
l1= 380.			#ft
l2= 4. 			#ft
l3=56. 			#ft

#CALCULATIONS
r= 0.98*n*math.pi*(d/12)**2*(l/12.)
Q= w/6.23
C= Q/r
p= w*10*(l1+l2+l3)/(0.9*33000.)

#RESULTS
print  ' Horse power required to drive= %.f h.p'%(p)

 Horse power required to drive= 163 h.p