Vaisala DMT132 - Manual (Page 42)

USER'S GUIDE____________________________________________________________________
40 __________________________________________________________________ M211289EN-A
Configuring Measurement Parameters
Set Pressure Value for Dewpoint
Calculation
The HUMICAP® 180R sensor in the DMT132 is not very pressure-
dependent. However, to maximize the measurement accuracy, the
pressure of the system must be known. The pressure compensation value
has been set at the factory according to the order form. You can view and
set a new value using the PRES command.
NOTE It is important to set the pressure compensation value accurately when
the transmitter is configured to output dewpoint temperature in
atmospheric pressure (T
d/f
atm). For standard dewpoint measurement
(T
d/f
), it is enough to set an approximate pressure value (±1 bar)
PRES [pp.ppppp]
where
pp.ppppp = Absolute pressure (bar
a
) in the measuring point.
Range 0 ... 20 bar.
Example:
>pres 1.01325
>Pressure (bar) : 1.01325
Saving settings...done
>
The pressure conversion coefficients from other pressure units to bars is
given in the table below.
Table 7 Pressure Conversion Coefficients
From To bar
a
PaN/m² 0.00001
mmHg torr
0.001333224
inHg 0.03386388
mmH
2
O 0.00009806650
inH
2
O 0.002490889
atm 1.01325
at 0.980665
psi
a
0.06894757
For example: 29.9213 inHg = 29.9213 × 0.03386388 = 1.01325 bar
a.