MKS Mass-Flo 1479A, Instruction Manual, Page: 63 / 72

Appendix C: MFC Sizing Guidelines How To Determine the Valve Configuration
53
How To Determine the Valve Configuration
1. Determine the maximum flow coefficient (Cv), for the gas of interest, using the equation:
C
V
(max) = Max. Flow Rate, sccm
C
v
Pressure Factor
1.293
Gas Density
( ) ( )
( )
where:
Gas Density is listed in Appendix B: Gas Correction Factors, page 47.
Cv Pressure Factor is listed in Table 9, page 53.
Cv Pressure Factors (multiplied by 100,000)
P1
(psia)
Differential Pressure (psid)
50 40 30 20 15 10 5 2 1 0.5
265 0.032 0.035 0.040 0.049 0.056 0.068 0.096 0.152 0.214 0.303
215 0.036 0.039 0.045 0.054 0.062 0.076 0.107 0.168 0.238 0.336
165
0.042 0.046 0.052 0.063 0.072 0.087 0.122 0.192 0.272 0.384
150 0.044 0.048 0.055 0.066 0.075 0.092 0.128 0.202 0.285 0.403
125
0.049 0.054 0.061 0.073 0.083 0.101 0.141 0.221 0.312 0.441
100 0.058 0.062 0.069 0.082 0.094 0.113 0.158 0.248 0.349 0.493
75
0.077 0.077 0.082 0.097 0.110 0.132 0.183 0.286 0.404 0.570
50 0.116 0.116 0.116 0.123 0.138 0.164 0.226 0.352 0.495 0.699
30
 
0.194 0.194 0.194 0.220 0.297 0.458 0.642 0.904
25
  
0.232 0.232 0.246 0.329 0.503 0.704 0.991
20
  
0.291 0.291 0.291 0.373 0.565 0.789 1.109
15
   
0.387 0.387 0.441 0.659 0.915 1.283
10
    
0.578 0.581 0.821 1.131 1.578
5
     
1.156 1.232 1.643 2.261
2
      
2.889 2.905 3.725
1
       
5.778 5.811
Table 9: Cv Pressure Factors