Conductance Calculation.py

#! /usr/bin/env python
# 2014-10-13 by Dan Hickstein
import numpy as np
import matplotlib.pyplot as plt

pressure = np.logspace(-3,3,100)

def Cknud(pressure,length,diameter):
    #using equation 1.26 of the Leybold handbook:
    #https://www3.nd.edu/~nsl/Lectures/urls/LEYBOLD_FUNDAMENTALS.pdf
	#pressure drop in mbar
	#length of tube in cm
	#diamter of tube in cm
    p = pressure; l = length; d = diameter
    return 135*d**4/l*p + 12.1*d**3/l* (1+192*d*p)/(1+237*d*p)

fig = plt.figure(figsize=(10,7))
ax = plt.subplot(111)

#KF 16 is 3/4inch ID - 2 cm
# KF 25 is 1 inch ID - 2.5 cm
# FK 40 is 1.5 inch ID - 3.8 cm
# KF 50 is 2 inch ID - 5.0 cm

for length in (100,1000):
    for diam in (2.5,3.8,5):
        if diam==3.8:
            sty='dashed'
            txt='KF40'
        elif diam==2.5:
            sty='dotted'
            txt='KF25'
        elif diam==5:
            sty='solid'
            txt='KF50'
        else:
            sty='solid'
            txt=''
		
        if   length==100:  color='red'
        elif length==1000: color='blue'
        else:        color='black'
        ax.plot(pressure,Cknud(pressure,length=length,diameter=diam),
			    label='%.1f cm diameter (%s), %.0f meter length'%(diam,txt,length/100.),linestyle=sty,color=color)


ax.set_xscale('log')
ax.set_yscale('log')

ax.axhline(260,label='260 L/s (HiPace 300)',color='m',alpha=0.2,lw=2)
ax.axhline(71,label='71 L/s (HiPace 80)',color='m',alpha=0.2,lw=1)
ax.axhline(7.8,label='7.8 L/s (ACP 28)',color='k',alpha=0.2,lw=2)
ax.axhline(4,label='4.2 L/s (ACP 15)',color='k',alpha=0.2,lw=1)

ax.set_title('Conductance of tubing using Knudson equation\n(valid for viscous and molecular flow)')
ax.set_xlabel('Pressure (mbar)')
ax.set_ylabel('Conductance (L/s)')

leg = ax.legend(loc='upper left',fontsize='small'); leg.draw_frame(False)

plt.savefig('Tubing conductance 1.1.pdf',dpi=300)
plt.show()