Spirax Sarco B850-W-2 Guia De Inicio Rapido página 39

Calculation for Metric (kW)
Click on
Edit each '1' in the above calculation to add the following values:
Flow co-efficient - K v - Value must be taken from the technical documentation of the BBD
Valve.
Enthalpy (kJ / kg) - Derive the value for your boiler from the look up tables in Section 10.31.3
Density (kg / m³) - Derive the value for your boiler from the look up tables in Section 10.31.3
Other measured units: Pressure (bar) and Relative Density (kg / m³).
It is assumed that there will be a backpressure of 10%, so a factor of 0.9 can be seen in the
calculation. If backpressure different adjust formula accordingly.
Calculation for Imperial (MBtu / h)
C v
( Y.V t *1*1 * 1 *8 . 0 2 0 8 3 3 *s q r t ((A . p D * 0 . 9) * 6 2 . 42 7 9 6 / 1))
Click on
Edit each '1' in the above calculation to add the following values:
Flow co-efficient - C v - Value must be taken from the technical documentation of the
BBD Valve (C v = K v x 1.156).
Enthalpy (Btu / lb) - Derive the value for your boiler from the look up tables in Section 10.31.3
Density (lb / ft³) - Derive the value for your boiler from the look up tables in Section 10.31.3
Other measured units: Pressure (psi) and Relative Density (lb / ft³).
It is assumed that there will be a backpressure of 10%, so a factor of 0.9 can be seen in the
calculation. If backpressure different adjust formula accordingly.
Typical boiler pressures
psi g
100
150
200
250
300
IM-P408-04 AB Issue 2
K v Enthalpy
( Y.V t *1 *1 *1 * s q r t ((A . p D * 0 . 9) *10 0 0 / 1))
3600
Enthalpy Density
1000
Density
lb / ft
3
56.39
55.29
54.39
53.61
52.92
Density
Enthalpy
Btu / lb
298.49
330.58
355.45
376.18
394.02
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