Honeywell UMC800 - Table 2-47 Metric Units

Function Blocks
3/99 Function Block Reference Guide 167
2.54 RH Function Block,
continued
Table 2-47 Metric Units
Metric ON OFF
DRY
°
C
°
F
WET
°
C
°
F
PRES
Pa PSI
Usage Tip
It is physically impossible for the wet bulb to be warmer than the dry bulb. If this appears to be the case, it
implies a problem with the sensors, and will result in a RH greater than 100%. Downstream blocks should
detect that situation and react promptly.
Example
Figure 2-56 shows an RH function block example.
A setup parameter allows inputs to be in Degrees F or Degrees C. When Degrees F is selected, pressure is
assumed to be in PSIA. When Degrees C is selected, pressure is assumed to be in Pa. (101325 Pa = 1 std.
Atmosphere.
Figure 2-56 RH Function Block Example