Relative Humidity (Rh); Mass Flow 1 And 2 - ABB C1300 User Manual Supplement

2.1.2 Relative Humidity (RH)

The relative humidity calculation requires two inputs, one from a wet-bulb sensor and one from a dry-bulb sensor. Both of these inputs
are configured as variables. RH tables are based on the use of an aspirated psychrometer having an air velocity of at least 11.5 feet per
second or 3.5 meters per second across the bulb sensors.
Note. Inputs used for wet- and dry-bulb measurement must be in the range 0 to 100°C (32 to 212°F).

2.1.3 Mass Flow 1 and 2

The two types of mass flow calculations available are as follows:
– applications where a volumetric flow meter is used to measure flow.
Mass Flow 1
– applications where a differential pressure transmitter is used to measure flow.
Mass Flow 2
The standard formula for mass flow 1 is as follows:
where:
k = Scaling constant
V = Input a (input from volume flow source)
P = Pressure (pressure input source)
T = Temperature (temperature input source)
T = Reference temperature (for the scaling constant used)
r
P = Reference pressure (for the scaling constant used)
r
The temperature units used by the input source must be specified, since all calculations use absolute temperatures and conversion is
made if the input uses °C (or °F).
The standard formula for mass flow 2 is as follows:
where:
h = differential pressure head
Some differential pressure transmitters incorporate a square root linearizer and therefore produce an output linear to flow. In this instance,
no additional linearization within the C1300 is required and the relevant
User Guide (IM/C1300).
Therefore the formula used internally within the C1300 is:
where:
a = linearized flow signal
The linearized flow signal is produced by the transmitter or derived from the signal linearized within the C1300.
2 MATH CONFIGURATION...
must be set to
Linearizer Type
– see Section 3.5 of the C1300
None
3