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2502 Series
Introduction
Scope of Manual
This instruction manual provides installation, operat-
ing, calibration, maintenance procedures for 2502 Se-
ries pneumatic controllers (figure 1) used in combina-
tion with 249 Series level sensors.
This manual does not include regulator or sensor
installation or maintenance procedures. For this infor-
mation, refer to the instruction manual for the appropri-
ate regulator and 249 Series level sensor.
Only personnel qualified through training or experience
should install, operate, and maintain this controller. If
there are any questions concerning these instructions
contact your Fisher Controls sales office or sales rep-
resentative before proceeding.
Description
The Type 2502 Level-Trol
this manual provides proportional-plus-reset and pro-
portional-plus-reset-with-anti-reset-windup control. The
controller output is a pneumatic signal that operates a
final control element. These controllers are designed
to control liquid level, the level of interface between
two liquids, or density (specific gravity). Each unit con-
sists of a 249 Series liquid level sensor and a 2502
Series pneumatic controller.
Refer to the Principle of Operation section for a more
comprehensive discussion of how the Type 2502
pneumatic controller operates.
Specifications
Table 1 gives general specifications for the Type 2502
Series Controllers.
Controller-Sensor Action
The following controller description is for right-hand
mounting. Left-hand mounting produces an output sig-
nal with the opposite action. Figure 4 shows cage
head mounting positions.
For right-hand mounting:
Direct Action--Increasing liquid or interface level, or
density, increases the output signal.
Reverse Action--Decreasing liquid or interface level,
or density, increases the output signal. A factory-sup-
2
Controller described in
AMBIENT TEMPERATURE ( C)
–18
–10
0
10
1100
800
HEAT INSULATOR
REQUIRED
400
NO INSULATOR NECESSARY
0
USE INSULATOR (CAUTION! IF AMBIENT DEWPOINT IS
ABOVE PROCESS TEMPERATURE, ICE FORMATION MAY
CAUSE INSTRUMENT MALFUNCTION AND REDUCE
INSULATOR EFFECTIVENESS.)
–20
0
20
40
60
AMBIENT TEMPERATURE ( F)
AMBIENT TEMPERATURE ( C)
0
10
20
–18
–10
1100
800
HEAT INSULATOR
REQUIRED
400
NO INSULATOR NECESSARY
0
USE INSULATOR (CAUTION! IF AMBIENT DEWPOINT IS
ABOVE PROCESS TEMPERATURE, ICE FORMATION MAY
CAUSE INSTRUMENT MALFUNCTION AND REDUCE
INSULATOR EFFECTIVENESS.)
–20
0
20
40
60
80
AMBIENT TEMPERATURE ( F)
NOTE: FOR SERVICE BELOW –20 F (–29 C) CONTACT FACTORY.
B1413-1/IL
Figure 2. Guidelines for Use of Optional
Heat Insulator Assembly
plied reverse-acting unit has the suffix letter R added
to the type number.
Installation
The 2502 Series controllers are used in combination
with 249 Series sensors, and unless ordered separate-
ly, the controller will be attached to the sensor.
249 Series Sensors
The Type 249, 249B, 249C, 249K, 249L, and
249N, sensors side-mount on the vessel with the dis-
placer mounted inside a cage (caged) outside the ves-
sel.
The Type 249BP and 249CP sensors top-mount
on the vessel with the displacer hanging down into the
vessel (cageless).
The Type 249V sensor side-mounts on the ves-
sel with the displacer hanging out into the vessel
(cageless).
External sensors provide more stable operation than
do internal sensors for vessels with internal obstruc-
tions or considerable internal turbulence.
71
20
30
40
50
60
70
TOO
HOT
80
100
120
140
160
30
40
50
60
70
80
100
120
140
160
593
500
400
300
200
100
0
–29
93
90
593
500
TOO
HOT
400
300
200
100
0
–29
180
200
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