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Programming Function Blocks and Features
Video Recorder – User Manual 128
Mass Flow
By compensating for variations in fluid temperature and pressure, Mass Flow is used to obtain a more
precise fluid flow measurement from an orifice plate developing a differential pressure. The output CVn
OV is mass flow and is calculated from the following formula for U.S. Units Of Measurement:
MF = FACTOR 1 x SQRT [DP INPUT x (PRESSURE INPUT+14.7) / (TEMPERATURE INPUT + 459)]
where
FACTOR 1 is calculated by user
DP INPUT is differential pressure in inches of water
PRESSURE INPUT is in PSIG
TEMPERATURE INPUT is in °F
Or, Mass flow is calculated from the following formula for International Units Of Measurement:
MF = FACTOR 1 x .569 x SQRT [DP INPUT x (PRESSURE INPUT +101.4)/(TEMPERATURE INPUT + 273)]
where
FACTOR 1 is calculated by user
DP INPUT is differential pressure in KPASCALS
PRESSURE INPUT is in KPASCALS
TEMPERATURE INPUT is in °C
Table 4-37 describes the Mass Flow prompts. See Table 4-2 for additional prompts.
Table 4-37 Mass Flow Prompts
Prompt Range/Selections Definition
OUT LOW LIMIT
OUT HIGH LIMIT
OFF or number Displayed output value will be clamped and will flash
when these limits are exceeded.
DP INPUT OFF, analog parameter,
number
Differential pressure input
PRESSURE INPUT OFF, analog parameter,
number
Pressure input in PSIG or KPASCALS
TEMP INPUT OFF, analog parameter,
number
Temperature in °C or °F
UNITS OF MEASURE US or International Units of measure
FACTOR 1 OFF, analog parameter,
number
Flow factor for the particular installation