Det-Tronics UD20 FlexVu Explosion-Proof Universal Display Unit - Manual (Page 9)

3.1 95-8620 7
CAlIbRATION pROCEDURE
1. Clean air must be present at the sensor prior
to initiating calibration. The use of bottled air is
recommended.
2. Calibration can be initiated in one of two ways:
A. Hold the calibration magnet against the
designated location on the sensor module (see
Figure 5) until the green LED turns off and the
yellow LED turns on steady (approximately one
second).
B. Initiate calibration via the magnetic switches on
the UD20. Select Main Menu > Device Cal >
Calibration > Execute.
The UD20 indicates “Waiting for Zero”. The
transmitter immediately begins taking zero readings.
3. When the zero calibration is complete, the yellow
LED changes from steady to blinking and the UD20
indicates “Waiting for Gas”. Apply the calibration
gas to the sensor. When gas is detected, the UD20
indicates “Waiting for Span”.
4. When the yellow LED turns off and the UD20
indicates “Remove Cal Gas”, remove the calibration
gas. The gas level at the sensor gradually returns to
zero. The green LED turns on steady to indicate that
the device has returned to normal operation, using
the new calibration data.
INpUT TRIm
The input current loop of the UD20 is trimmed at the
factory. However, it can also be trimmed in the field
using the following automated process.
Navigate through the menu to “Input Loop Cal”.
Main Menu
Process Vars
Display Status
Device Status
Device Setup
Device Cal
Device Test
Device Setup
HART Option
RTC
Write Protect
Input Loop Cal
Contrast Control
Upon entering Input Loop Cal, the UD20 commands
the detector to output 4 mA, and then automatically
calibrates its own input. The UD20 then commands the
detector to output 20 mA, and subsequently calibrates
its own input.
specificAtions
UD20 UNIvERSAl DISplAy UNIT
OPERATiNG VOLTAGE—
24 Vdc nominal, operating range is 19 to 30 Vdc.
UD20 maximum loop voltage drop (Vd) 5.0 volts.
Maximum loop supply 30.0 Vdc.
OPERATiNG POWER—
0.8 watt maximum.
OPERATiNG CURRENT—
A minimum of 3.5 mA.
CURRENT OUTPUT—
Linear 4-20 mA
(with HART output directly from GT3000).
250 ohm termination resistor is required (included).
OPERATiNG TEMPERATURE—
–20°C to +70°C.
STORAGE TEMPERATURE—
–40°C to +70°C.
HUMiDiTy RANGE—
5 to 95% RH (Det-Tronics verified).
SENSOR COMPATiBiLiTy—
The UD20 can be used with any of the Det-Tronics
GT3000 line of gas detectors.
LED
PLACE MAGNET HERE
TO ACTIVATE INTERNAL
MAGNETIC SWITCH
A2452
Figure 5—Location of Magnetic Switch on GT3000 Detector