Calibration; Standard Performance: Full Range Input, Direct Action - Emerson Fisher 846 Instruction Manual

Instruction Manual
Form 5739
February 2002
Section 3

Calibration3-3-

Calibration of the Type 846 and Model 3311 requires
either an accurate current generator or an accurate
voltage generator with a precision 250-ohm, 1/2-watt
resistor. Figure 3-1 shows how to connect either
device.
Calibration also requires a precision output indicator
and a minimum nonsurging air supply of 5.0 Normal
3
m /hr (3 SCFM) at 1.4 bar (20 psi) for standard
performance units. For multirange performance
units, the air supply must be at least 0.2 bar (3 psi)
greater than the maximum calibrated output
pressure, up to 2.4 bar (35 psi) maximum.
For ease of calibration, the output load volume,
including the output tubing and output indicator,
should be a minimum of 33 cm
Review the information under Signal Interruption in
Section 2 before beginning the calibration
procedure.
Before calibration, determine the type of input (full or
split range), and the type of output action (direct or
reverse). Consult the factory for split range output
calibration. Also, determine if the unit offers
standard or multirange performance. The unit
supports eight basic input/output combinations:
Standard Performance
D Full Range Input, Direct Action
D Split Range Input, Direct Action
D Full Range Input, Reverse Action
D Split Range Input, Reverse Action
Multirange Performance
D Full Range Input, Direct Action
D Split Range Input, Direct Action
D Full Range Input, Reverse Action
D Split Range Input, Reverse Action
Table 3-1 lists the various input and output ranges
over which the unit may be calibrated.
The input range is selected by changing the position
of a jumper located on the electronic circuit board.
1. Consult factory for calibration of multirange performance units with split range
input or split range output, or both.
3
(2 cubic inches).
(1)
(1)
ADJUST THE CURRENT
SOURCE TO PROVIDE
THE 4 AND 20 mA
SET POINTS
CALIBRATION USING A CURRENT SOURCE
TO OBTAIN THE 4 AND 20mA
SET POINTS, ADJUST THE
VOLTAGE SOURCE (V ) SO
S
THE VOLTMETER (V ) READS
M
1 AND 5 VOLTS, RESPECTIVELY,
ACROSS THE 250 ohm RESISTOR
CALIBRATION USING A VOLTAGE SOURCE
A6644-1 / IL
Figure 3-1. Connecting a Current or Voltage
Source for Calibration
Refer to Electronic Circuit Board in Section 6, and
figure 6-5 for the location and instruction on
placement.
CAUTION
Excessive current can damage the
transducer. Do not connect an input
current of more than 100 mA to the
transducer.
Standard Performance: Full Range
Input, Direct Action
Use the following procedure to achieve a standard
0.2 to 1.0 bar (3 to 15 psi) output span for a 4 to 20
mA input signal:
1. Remove the module final assembly from the
housing. Refer to Removing the Module Final
Assembly in Section 6 for an explanation of how to
disengage the module final assembly.
2. Confirm that the unit is direct acting. A green
electronic circuit board identifies direct-acting units.
Refer to Action under the heading Electronic
Circuit Board in Section 6 for more information on
direct acting units.
3. Position the range jumper in the Hi position for
High Range. Figure 6-5 shows the circuit board
jumper positions.
4. Replace the module final assembly in the
housing. Refer to Replacing the Module Final
Calibration
3–1