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PanaFlow™ MV80, MV82 & MV84 User’s Manual 159
Appendix C. Flow Meter Calculations
C.3 Energy Flow Calculations
Energy is calculated for a steam supply/condensate return or hot/chilled water system. For steam/water, the meter
must be located in the supply line; otherwise, the meter may be located in either the supply line or in the return line.
C.3.1 Steam supply, water return, meter steam supply
Energy = mdot * (h0 - pctRet * h1)
Where:
mdot = mass flow at the meter, lbm/sec
pctRet = estimated percent of mass flow returned
h0 = Steam Enthalpy (t0, p)
h1 = Water Enthalpy (t1)
t0 = steam temperature
t1 = return water temperature
p = steam pressure
C.3.2 Water supply and return, meter supply
Energy = mdot * (h0 - pctRet * h1)
Where:
h0 = Water Enthalpy (t0)
h1 = Water Enthalpy (t1)
t0 = supply water temperature
t1 = return water temperature
C.3.3 Water supply and return, meter return
Energy = mdot * (h1/pctRet - h0)
Where:
h0 = Water Enthalpy (t0)
h1 = Water Enthalpy (t1)
t0 = supply water temperature
t1 = return water temperature
The energy flow is positive if less energy is returned than is supplied. This implies that chilled water systems will
indicate negative energy flow. Positive and negative energy flows are accumulated in separate totalizers.
C.4 Fluid Calculations
C.4.1 Calculations for Steam T & P
When “Steam T & P” is selected in the “Real Gas” selection of the Fluid Menu, the calculations are based on the
equations below.