CEMP-E
TI 810-11
30 November 1998
Qs = steam flow, lb/hr
2.11 = compressibility and conversion factor.
pe = absolute steam pressure entering the valve, psia
po = absolute pressure entering steam coil, psia
∆p = pressure drop through valve, psid
d. When the drop across the valve will be at or greater than the critical pressure drop and the steam is
saturated, the Kv (Cv) will be calculated using equation 2-7.
Qs
Kv=
(eq 2-7 SI)
0.133 pe
Where:
3
Kv = flow coefficient, m /hr @ ∆p = 100 kPa (1 bar)
Qs = steam flow, kg/hr
0.133 = compressibility and conversion factor.
pe = absolute pressure of entering steam, kPa
Qs
Cv =
(eq 2-7 IP)
1.74 pe
Where:
Cv = flow coefficient, gpm @ ∆p = 1 psid
Qs = steam flow, lb/hr
1.74 = compressibility and conversion factor.
pe = absolute pressure of entering steam, psia
e.
For superheated steam applications where the drop across the valve is less than the critical
pressure, the Kv (Cv) will be calculated using equation 2-8.
2-26
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