#initialisation of variables
p = 500 #ft
p1 = 6 #in
t = 500 #cfm
p2 = 7 #psig
P = p2+14.7 #psia
T = 520*(P/14.7)**0.283 #F
f = 0.048*p1**0.027/(t)**0.148 #in
#CALCULATIONS
delP = 20.*10**-3*p*T*(t)**2/(38*10**3*P*p1**5) #psia
#RESULTS
print 'the pressure drop = %.2f psia'%(delP)