Cameron BARTON 289A User manual

BARTON®MODEL289A/291B
DIFFERENTIALPRESSURE
INDICATING SWITCHES
Installation Manual
Manual No. 10305, Rev. B
December 2004
[This manual is for the Indicating Switch only—refer to Model 199 DPU manual,
Part No. 10030, for detailed information about the DPU used with the indicating
switch.]
TABLE OF CONTENTS
SAFETY .................................................................................................2
SECTION 1 - INTRODUCTION........................................................3
1-1. General ............................................................................................3
1-2. Main Components ..........................................................................4
1-3. Indicating Switch.............................................................................5
1-4. Specifications...................................................................................6
SECTION 2 - INSTALLATION ..........................................................7
2-1. General ............................................................................................7
2-2. Mounting/Piping/DPU Installation...............................................7
2-3. Electrical Connection (Switches/Relays)......................................7
2-4. Switch Use .......................................................................................7
2-5. Startup..............................................................................................7
SECTION 3 - MAINTENANCE AND CALIBRATION.................9
3-1. Required Tools ................................................................................9
3-2. DPU Installation/Test/Calibration/Maintenance.........................9
3-3. Bezel/Lens (or Cover) Installation and Removal ........................9
3-4. Calibration Check.........................................................................10
3-5. Pointer Installation and Removal................................................10
3-6. Indicator Calibration ....................................................................11
3-7. Changing Switch Setpoint ............................................................12
3-8. Complete Calibration...................................................................14
3-9. Preventative Maintenance............................................................15
3-10. Locking Drive Arm to Torque Tube..........................................16
3-11. Troubleshooting ..........................................................................16
SECTION 4 - INSTALLATION DRAWINGS.................................19
SECTION 5 - PARTS DRAWINGS/PARTS LISTS.........................23

2
SAFETY
Before installing this instrument, review the installation instructions and safety
notices in Section 2 of this manual and in the Barton® Model 199 DPU manual.
DANGER notes indicate the presence of a hazard which will cause severe
personal injury, death, or substantial property damage if warning is ignored.
WARNING notes indicate the presence of a hazard which can cause severe
personal injury, death, or substantial property damage if warning is ignore.
CAUTION notes indicate the presence of a hazard which will or can cause mod-
erate personal injury or property damage if warning is ignored.

3
SECTION 1 - INTRODUCTION
1-1. General
The Barton®weatherproof Model 289A and the explosion-proof Model 291B are
differential pressure indicating switches (Figure 1-1). The 289A has a NEMA-4
watertight die-cast aluminum case (finished with a weather-resistant black epoxy
resin paint). The cover lens is secured in the bezel with an elastomer ring to
reduce the possibility of accidental breakage. This ring also acts as a seal between
the bezel and the case to ensure a moisture, fume and dust-free atmosphere for
the indicator and switch mechanism.
Model 291B has an explosion-proof case that is certified for Class I, Division 1,
Groups B, C & D service. The large cover lens allows maximum readability of the
indicating pointer.
Switches and all adjustments are readily accessible when the cover is removed
(Figure 1-2, page 4). The built-in switches energize either single or dual alarm
circuits when the measured differential pressures exceed predetermined limits.
These limits may be either maximum, minimum, or both.
Figure 1-1. Model 289A (left) and Model 291B (right) Differential Pressure
Indicating Switches

4
1-2. Main Components
A. Indicating Switch
B. Differential Pressure Unit (DPU)
• 289A and 291B are actuated by a Barton®Model 199 DPU
For detailed information on the actuating DPU, see the Barton®Model 199 DPU
user manual (Part No. 10030).
Figure 1-2. Switches and adjustable controls

5
1-3. Indicating Switch (refer to Figures 1-3 and 2-1)
Rotation of the DPU’s torque tube shaft is coupled through connecting linkage
within the switch case to move the pointer across the scale plate. An actuating
cam, directly connected to the torque tube shaft, rotates with the motion of the
shaft. Two cam follower roller/actuator arm assemblies, one for each switch,
respond to torque tube rotation by opening and closing the switches as they ride
on and off the cam. The levels of differential pressure at which the switches actu-
ate are adjustable with high and low alarm switch adjustments on the scale plate.
Standard models have two alarm switches - one or both may be used. Each switch
can be connected to operate normally-opened or normally-closed. The direct-set
switch contacts are adjustable over a scale range of 5-95% nominal.
1000
50
Zero DP
1000
50
Maximum DP
RED
Y ELLOW
BLUE
BLAC K
WHI T E
1000
50
SWI T CH "A"
(LEFT)
SWI T CH "B"
(RIGHT )
CAM
TERMI NAL
BLOC K I N
CASE
BOT H S WI T CHES RELAX ED
SWITCH
PLUNGER
SCREW
❶❶Note: Wire "Green" for 289A
and "Violet" for 291B.
Mid-point DP
HIGHLOW
SWI T CH "A" AC T UAT ED/S WI T CH "B" RELAX ED
SWI T CH "A" RELAX ED/SWI T CH "B" AC T UAT ED
SWITCH CLOSED
CONTACTS
OPEN
CONTACTS
GREEN/WHITE GREEN/BLACK
A (LEFT)
B (RIGHT)
YELLOW/BLUE RED/YELLOW
SWITCH CLOSED
CONTACTS
OPEN
CONTACTS
GREEN/WHITE GREEN/BLACK
A (LEFT)
B (RIGHT)
RED/YELLOW YELLOW/BLUE
SWITCH CLOSED
CONTACTS
OPEN
CONTACTS
GREEN/WHITEGREEN/BLACK
A (LEFT)
B (RIGHT)
YELLOW/BLUE RED/YELLOW
SWI T CH "A"
(LEFT)
SWI T CH "B"
(RIGHT )
SWI T CH "A"
(LEFT)
SWI T CH "B"
(RIGHT )
Figure 1-3. Switch Actuation Example
Notes: (1) Cam rotates counterclockwise with increased pressure; (2) Switches
shown with low switch set at 25% differential pressure (DP); High switch set at
75% differential pressure (DP); (3) To change setpoint: loosen lock screw, move
switch plate, tighten screw and test setpoint; (4) Internal wires use No. 22 AWG
and external wires use No. 18 AWG.

6
1-4. Specifications
General:
Actuating Unit (DPU).................Barton®Model 199 DPU
Dial Size ........................................6 inches (152 mm)
Temperature Limits (Ambient)...40°F/°C to +180°F (+80°C)
Indication Accuracy (SPDT)....... 0-10” w.c. to 0-349” w.c. ± 1.0% F.S.
(0-25 mbar to 0-867 mbar ± 1.0% F.S.)
0-350” w.c. to 0-100 PSID ± 1.25% F.S.
(0-869 mbar to 0-6.9 bar ± 1.25% F.S.)
Indication Accuracy (DPDT)......Add 1% to SPDT values
Point of Switch Actuation............Add 1/2% to SPDT values
Switch:
Accuracy of
Switch Repeatability ....................±0.25% of full scale
Switch Deadband .........................±5% (SPDT); ±6% (DPDT)
Switch Type ...................................Mechanical, Snap-Acting
Contact Type.................................Single Pole, Double Throw (SPDT)
Double Pole, Double Throw (DPDT)
Switch Rating:
125 VAC........................................5 Ampsa
250 VAC........................................2.5 Ampsa
30 VDC Inductive ........................1.0 Ampsb
30 VDC Resistive .........................3.0 Amps
125 VDC Inductive ......................0.2 Ampsa,b
125 VDC Resistive .......................0.4 Ampsa
Relay:
Coil Power Requirement:
DC Relay ................................1.5 Watts
AC Relay.................................2.75 Volt Amps
Contact Types ...............................Single Pole, Double Throw (SPDT)
Double Pole, Double Throw (DPDT)
Contact Rating .............................15 Amps at 115 VACa
CE Rating: Less than 50 VDC or 35 VAC
aNon-CE Use Only. Voltage limited to less than 50 VDC or 35 VAC for CE applications.
bArc suppression recommended for inductive loadings.

7
SECTION 2 - INSTALLATION
2-1. General
The instrument should be inspected at time of unpacking to detect any damage
that may have occurred during shipment.
Note: The unit was checked for accuracy at the factory — do not change any of
the settings during examination or accuracy will be affected.
For applications requiring special cleaning/precautions, a polyethylene bag is
used to protect the instrument from contamination. This bag should be removed
only under conditions of extreme cleanliness.
2-2. Mounting/Piping/DPU Installation
Refer to the Barton®Model 199 DPU user manual (Part No. 10030).
2-3. Electrical Connection (Switches/Relays)
Units are supplied with either single or dual alarm switches and/or relays
(depending on customer order). The direct-set switch contacts are adjustable
over the entire scale range.
Wiring diagrams on page 8 show the electrical connections for the switches.The
high switch and low switch setpoint adjustment procedures are covered in section
3-7, page 12. For physical location of switches and connections, see page 3.
2-4. Switch Use
Switch contact life is influenced by various application conditions such as tem-
perature, humidity, airborne contamination, vibration, amount of plunger travel,
cycling rate, and rate of plunger travel (and others), as well as by the electrical
(circuit) characteristics.
Note: Arc suppression for inductive loads will prolong the life of the switch
contacts.
Note: Due to their size, subminiature switches have small mechanical clearances;
therefore, no rating above 250 VAC has been established.
2-5. Startup
For startup procedures, warnings, and information, refer to the Barton®Model
199 DPU user manual (Part No. 10030).

8
Notes (both configurations):
• Internal wires are No. 22 AWG; External wires are No. 18 AWG
• Switch and relay ratings are shown on page 5.
• Relay coils are available in the following voltages: 6, 12, 24, 120*, and 230*
VAC or 6, 12, 24, 110* VDC (* = non-CE use only)
Figure 2-1. Switch Wiring Connections
44
289A
SWITCH AND RELAY
LOW
BROWN
BLUE
GRAY
ORANGE
WHITE/VIOLET
WHITE/BLACK
WHITE/ORANGE
WHITE/GRAY
WHITE/BLUE
WHITE/BROWN
WHITE
VIOLET
RED
RED
BLACK
BLACK
YELLOW
RED
YELLOW
BLUE
GRAY
BROWN
ORANGE
VIOLET
WHITE
GREEN
BLACK
GREEN
N.C.
N.C. N.C.
N.C.N.O.
N.O. N.O.
N.O.
C
C C
N.C.
N.O.
C
N.C.
N.O.
C
C
HIGH
44
291B
SWITCH AND RELAY
LOW
BROWN
BLUE
GRAY
ORANGE
WHITE/VIOLET
WHITE/BLACK
WHITE/ORANGE
WHITE/GRAY
WHITE/BLUE
WHITE/BROWN
WHITE
WHITE/RED
RED
WHITE/YELLOW
BLACK
WHITE/BLACK/
BROWN
YELLOW
RED
YELLOW
BLUE
GRAY
BROWN
ORANGE
VIOLET
WHITE
BLACK/WHITE/BLACK
BLACK
VIOLET
N.C.
N.C. N.C.
N.C.N.O.
N.O. N.O.
N.O.
C
C C
N.C.
N.O.
C
N.C.
N.O.
C
C
HIGH
GREEN
RED
YELLOW
BLUE
WHITE-RED
WHITE-YELLOW
WHITE-BLUE
WHITE
GREEN
BLACK
WHITE-VIOLET
WHITE-GREEN
WHITE-BLACK
N.O.
C
N.C.
N.O.
C
N.C.
N.C.
C
N.O.
N.C.
C
N.O.
4
LOW HIGH 4
289A
SWITCH ONLY
RED
YELLOW
BLUE
WHITE-BLACK-RED
WHITE-BLACK-YELLOW
WHITE-BLACK-ORANGE
WHITE
VIOLET
BLACK
WHITE-BLACK-BLUE
WHITE-BLACK-VIOLET
WHITE-BLACK-GRAY
N.O.
C
N.C.
N.O.
C
N.C.
N.C.
C
N.O.
N.C.
C
N.O.
GREEN
LOW HIGH
4 4
291B
SWITCH ONLY

9
3-1. Required Tools (Toolkit Part No. 0288-1032B)
Tool Purpose
Pointer puller Pointer removal
Small screwdriver Calibration adjustments
Medium screwdriver Bezel removal/DPU bracket screws
1/8” Open-end wrench Calibration adjustments
1/8 Hex Allen wrench Switch setpoint adjustment
3-2. DPU Installation/Test/Calibration/Maintenance
Refer to the Barton Model 199 DPU user manual (Part No. 10030).
3-3. Bezel/Lens (or Cover) Installation and Removal
WARNING
(EXPLOSIONPROOF UNITS)
PRIOR TO LOOSENING ANY ATTACHING HARDWARE, HOUSING BOLTS, OR
COVER ASSEMBLY, ASSURE SURROUNDING AREA IS, AND REMAINS, WELL
VENTILATED.
PRIOR TO LOOSENING OR REMOVAL CASE/COVERASSEMBLY, ALL
ELECTRICAL POWER SUPPLIES MUST BE TURNED OFF.
THE COVER MUST BE REMOVED TO CALIBRATE THE INSTRUMENT.
BEFORE ANY MAINTENANCE/CALIBRATION, REVIEW MODEL 199 DPU
MANUAL (Part No. 10030).
For non-explosionproof units, the bezel gasket (Part No. 0277-0026C) must be
installed as shown below:
The two snubbers (Part No. 0266-0028C) on the scaleplate should not be com-
pressed against the lens cover and the pointer should not touch the lens.
Note—Ensure correct bezel gasket orientation before placing instrument back in
service. Incorrect bezel gasket orientation will cause the instrument indicator to
jam, resulting in inaccurate readings.
SECTION 3 - MAINTENANCE AND CALIBRATION
To remove the bezel and cover lens
on non-explosionproof units:
1. Loosen three screws on the
front of bezel.
2. Tilt out bottom of bezel and
slide bezel upward.
Figure 3-1.
Bezel/Lens

10
For explosionproof units, cover is unscrewed to gain access to the internal com-
ponents. Note: On some units, a set screw must be loosened with a 1/8-in. allen
wrench before the bezel can be removed. When re-installing cover, tighten cover
securely and inspect lens for cracks or other defects that may affect the explosion-
proof rating.
3-4. Calibration Check
Normally all that is required to put switch into service is to verify that it remains
at factory-set calibration, per the following instructions. (See Warning on pg. 9):
1. Securely mount unit in an appropriately level position and connect DPU to a
standard pressure source, per Model 199 DPU manual.
2. If zero indication is incorrect, remove bezel/lens (cover on explosionproof
units) and reset pointer to zero. Note: For an exact zero setting, hold the
hexagon hub with a wrench and carefully slip the pointer on its hub until it
points to zero graduation. Replace bezel/lens (or cover).
3. To test for reverse travel, connect pressure source to low-pressure (LP) hous-
ing and vent high-pressure (HP) housing. Apply pressures approximately
150% of the differential pressure range. The pointer should move approxi-
mately 5% to 10% below zero.
4. To test for overtravel, connect pressure source to HP housing and vent LP
housing. Apply pressures approximately 150% of differential pressure range.
Pointer should move approximately 5% to 10% above fullscale.
5. Apply 0%, 50% and 100% of full scale pressure. If indication is within
specified limits, instrument calibration is satisfactory and no adjustments are
necessary. If indications are incorrect, perform calibration procedure.
6. Make sure instrument zero indication is correct; otherwise, repeat Step 2.
7. Verify switch setpoints (refer to section 3-7, page 12).
3-5. Pointer Installation and Removal
A. Pointer Installation (See Warning on page 9)
1. Position pointer on movement shaft with pointer set at zero scale. If
necessary, enlarge hub hole using a tapered broach (in toolkit)
(Part No. 0288-1032B).
2. Lightly tap pointer hub with a flat-end tool. Use perpendicular blows to
avoid bending shaft.
3. Check calibration over entire range (see section 3-8.). If unit is correctly
calibrated, secure pointer to
movement shaft by tapping
hub with a hand-set or other
flat-end tool.
B. Pointer Removal (See Warning
on page 9)
The pointer is removed with
Barton Pointer Puller (Part No.
0163-0005B), which is included
in toolkit (Part No. 0288-1032B).
Figure 3-2.
Pointer Puller

11
1. Slide pointer puller along pointer until pin protruding from tip of screw
in pointer puller is directly over movement shaft and arms of pointer
puller are directly under pointer.
2. Gently turn knurled head of screw clockwise, pushing pin against move-
ment shaft and lifting pointer with arms. Finger pressure should be
sufficient to pull the pointer free. If more pressure is required, insert an
Allen wrench into head of the screw for leverage. Avoid applying exces-
sive pressure, which can cause the pin to break.
3-6. Indicator Calibration
(DP=Differential Pressure) (See Warning on pg. 9)
1. Securely mount instrument in an
approximately level position and
connect DPU into the test setup, as
described in the Model 199 DPU
manual.
2. Apply 50% differential pressure and
align linkage between drive arm and
movement as shown in Figure 3-3.
Release pressure from DPU.
3. Check pointer for
zero indication.
If necessary, set
pointer to zero by
slipping pointer on
hub (hold pointer
with fingers and
turn hub with a
wrench).
4. Apply 100%
pressure. If pointer exceeds full-scale, lengthen the movement range arm
by by turning the range adjust screw counterclockwise. If the pointer does
not reach full scale, shorten the range arm by turning the range adjust screw
clockwise.
5. Release pressure. Set pointer to zero using pointer hub for zero adjustment.
6. Repeat as necessary to obtain zero and full-scale readings.
7. Apply 50% differential pressure. If pointer does not indicate 50% scale, a
linearity adjustment is necessary. Loosen drive arm screw and move arm to
shift pointer in direction of error a distance of about 10 times linearity error.
(50% DP) Tighten drive arm screw.
8. Release pressure and reset pointer at zero. Check the span. If gear in move-
ment reaches limit of travel as a result of linearity adjustment (step 7), slip
range arm along gear approximately 5 degrees from normal 37.5 degree
angle to approximately 43 degrees. Range arm is slipped by applying pres-
sure to range arm with thumb, while holding gear firmly in place. Retest
pointer response at 50%, 0%, and 100% of full-scale differential pressure,
and adjust linkage until readings are acceptable.
Figure 3-3.
Linkage Alignment
(50% differential
pressure)

12
9. Apply 0%, 25%, 50%, 75%, 100%, 75%, 50%, 25%, and 0% of full-scale
differential pressure consecutively to instrument without overshoot. Lightly
tap indicator to overcome friction. Pointer should accurately indicate each
applied pressure.
10. Set stops to prevent pointer from striking snubbers on scale. Test setting by
moving pointer from zero position to 50% position manually and then letting
pointer return freely. If necessary, tap pointer hub to tighten it to shaft.
3-7. Changing Switch Setpoint
(Tools: Screwdriver, 1/8 Hex Allen wrench) (See Warning on pg. 9)
Setpoint — The measured pressure at which the snap-switch actuates and thereby
changes the states of the N.O and N.C. contacts. For example, the setpoint of the
low switch is 24 psid with decreasing pressure.
Deadband — The difference in the measured pressures between switch-actuation
and switch-reset. Deadband is
usually expressed as percent-
age of full scale (% of F.S.).
Deadband is not adjustable.
For example, the switch above
was found to reset at 26.4 psid
with increasing pressure. The
deadband was 2.4 psi, or 4% of
the full scale (0 to 60 psid).
A. In-Service Instruments
(calibration pressures
cannot be applied)
1. Remove bezel. Do
not remove pointer or
scale.
2. Insert hex wrench in
switch adjust post,
(item A, Fig. 3-4).
3. Loosen switch lock-
screw, (item B), 1/2 to
1 turn.
4. With hex wrench,
move index pointer
(item C) to new set-
point as indicated on switch index (item D).
5. If possible, check setpoint by varying process pressures and observing
pointer readings when switch actuates. (Open manifold bypass valve
slowly and watch for “pointer-jump” at setpoint or by electrical signal.)
Adjust setting if necessary, repeat test several times to verify stability.
Note: Switch index has 10 divisions shown by tick marks in Figure 3-4. Positions 0,
5, and 10 are also labeled along the bottom of the index as well.
Example: Scale has range of 0-60 psid. Setpoint is 24 psid, with decreasing pres-
sure, (24/60 x 10 = 4).
Figure 3-4.
Setpoint
Adjustment

13
Move index pointer (item C) to division 4. Start from bottom of switch index (0
on low, 10 on high). Tighten switch lock (item B) snug plus 1/4 turn. Do not over-
tighten. This will place setpoint within ±2% of full scale.
B. Out-of-Service (Disconnected from process Setpoint Adjustment lines or
mounted on bench)
1. Drain and vent housings.
2. Attach calibration pressure source (air or N2) to HP housing.
3. Apply pressures and observe pointer readings for accuracy. Use a
pressure standard (Heise gage or equivalent) for reference. Change
pressures slowly in discrete steps. A “bleed-pressure” method may cause
errors.
4. Change switch setpoint as described in Part A, page 12.
5. Check setpoint by changing measured pressure to actuate switch. For
Example: To verify low-switch setpoint to 24 psid, apply approximately
30 psi. Then reduce pressure to approximately 25 psid, hold for a few
seconds, then continue in 1/4 psid steps until switch actuates. If setpoint
is incorrect, continue instructions in Part A.
6. To measure switch deadband, reduce pressure to zero, then increase
pressure until switch resets.
7. To verify repeatability of setpoint, repeat step 5 several times. For
improved accuracy, use smaller increments of pressure. Allow extra
time for slow response gages and for test systems that have long runs of
small bore tubing.
8. High alarm switches right side of the scale) are adjusted in a similar
manner. Apply increasing pressure to establish the switch setpoint,
decreasing pressure to measure deadband.
C. Notes
1. Always check setpoint after tightening switch lock screws.
2. Either switch may be set at any point of the scale, except allowance must
be made for deadband to enable switch to reset itself. For example, high
switch (right side of scale) may be set at 100% of F.S., but should not be
set near zero. Also, low switch may be set at zero, but not near full scale.
(Observe deadband values for specific models).
3. If switch performance is unsatisfactory (such as setpoint does not
repeat, deadband is excessive, pointer exhibits hysteresis, contacts are
unstable. etc.) remove scale and inspect switch and mechanism. Scale is
split for removal without pulling pointer.
a. SPDT: This is the standard model (low, high, or both).
b. DPDT: Two switches are stacked and actuated by a single lever (low,
high, or both).
c. Three (or four) SPDT: Switches have independent switch points.
Nos. 1 and 3 are usually low switches set for decreasing pressures.
Nos. 2 and 4 are usually set for increasing pressures.
d. Hermetically Sealed Switch (Micro 11HM41): this switch has wide
deadband, case is modified for electrical clearances, amperes are
reduced for 60 Hz service.

14
3-8. Complete Calibration
Before performing complete calibration procedure, verify that instrument is out
of calibration, by performing calibration check procedure (section 3-4), page 10.
If instrument is out of calibration, before performing complete calibration proce-
dure, remove bezel/lens and inspect switch mechanism to verify the following (see
Figure 3-5) (See Warning on pg. 9):
• The roller rotates without
wobble or binding.
• The cam does not touch the
roller side shields.
• The actuator arm moves
freely on its pivot.
• All switch mounting screws
are tight.
• Linkages are straight and do not
bind at the pivots.
Correct any problems that are encountered.
A. Calibration Setup
1. Connect lamp or buzzer to switch output leads. Connect a test voltage
to switch input terminals on terminal strip. (A low voltage is recom-
mended for safety.) If relay is installed in instrument, coil voltage must
be applied to switch.
2. Unlock switch plate, back out stop screw, and move plate until roller is
positioned at top of the cam. Observe that switch does not actuate when
roller is moved from low point on cam to high point. If it does actuate,
back out plunger screw with roller on top of cam until switch de-actu-
ates.
3. Advance plunger screw until switch actuates, then advance plunger
screw an additional 60° (one flat).
4. Exercise switch roller across top of cam to verify steady operation.
Advance stop screw to touch switch, then back out screw 1.5 turns
(9 flats).
B. Calibration Procedure (see
Figure 3-6)
To calibrate switch linkage (required
when instrument is rebuilt), proceed
as follows:
1. Loosen three linkage
screws and turn crank to 12
o’clock position.
2. Use a 1/8-in. Allen wrench
to hold index shaft and
slip index pointer to 0 on
switch index.
Figure 3-5.
Cam/Follower Position
Figure 3-6.
Linkage Arrangement

15
B. Calibration Procedure (continued)
3. Tighten screw on crank to mid-slot position.
4. Turn switch index pointer to “1” (index numbers refer to numbers on
outer edge of scaleplate).
5. Apply 10% differential pressure and adjust switch plate until switch
actuates. Lock the two linkage screws.
6. Rotate index pointer to “9.” Apply 90% differential pressure and adjust
crank radius until switch actuates.
7. Recheck 10% and 90% setpoints. Adjust crank radius and index pointer
until both setpoints are 2% accurate (nominal).
8. If switch is to be field-set at low differential pressure values (1% or 2%
of pressure range), check crank to prevent a top-dead-center position.
Otherwise, minimum setpoint position will be restricted and setpoint
may become reversed.
9. Adjust switch to actuate at desired pressure by applying test pressures in
a decreasing direction, in discrete steps. Allow unit and pressure system
to stabilize. Then change pressure a small amount. The magnitude of
the pressure change is determined by desired accuracy of test. Tighten
lock screw before testing switch performance.
The high switch is usually set to actuate at increasing pressure. There-
fore, when calibrating high switch, apply test pressure in an increasing
direction.
This amount of loading will prevent cam-runout of a similar condition.
Excessive plunger loading (more than 3 flats) may cause roller to drag
on cam. Cam friction will be apparent by excessive hysteresis, erratic
pointer readings and inconsistent switch operation.
10. Check switch deadband, (actuate to reset) by applying differential pres-
sures in a decreasing then increasing (opposite for high switch direc-
tion). Observe pressures. To reduce deadband, advance plunger screw
(two flats maximum).
11. Adjust high switch to actuate at desired pressure. The procedure is the
same as for the low switch.
3-9. Preventative Maintenance
• Indicating Switch — Periodically inspect alarm switch mechanism to
verify that all mounting screws are seated properly. Inspect linkage for
wear. Inspect integrity of electrical circuits. Tighten as necessary.
• DPU — Warning/Caution notices, inspection/cleaning procedures, and
maintenance procedures are presented in the Model 199 DPU manual.
Never perform any maintenance/repair on the instrument or DPU
without first reviewing all procedures and Warning/Caution notices in
the DPU manual.

16
3-10. Locking Drive Arm to Torque Tube
Refer to Model 199 DPU manual. For explosionproof units, refer to Figure 5-3,
Model 291 Detail Drawing, pg. 28 (See Warning on pg. 9).
1. Slip drive arm over torque tube shaft; clear end of torque-tube housing
by approximately 0.030-in. before securing to prevent interference.
2. To tighten drive arm assembly onto torque-tube shaft:
a. While supporting block/shaft, tighten clamp screw until snug to
shaft.
b. Still supporting block/shaft, tighten clamp screw an additional:
• Sintered: 1/3 to 1/2 turn (This screw can normally turn one full
revolution before breaking.)
• Slotted: 1/4 to 1/3 turn (The slot in the slotted clamp block should
still be open.)
3-11. Troubleshooting
(See Warning on pg. 9. Refer to Table 3-1 and Model 199 DPU manual.
Figure 3-4. Locking Drive Arm to Torque Tube

17
Table 3-1. Troubleshooting
Problem Possible Source Probable Cause Corrective Action
Low or no
Indication Primary element
or DPU (refer to
DPU Manual)
Orice installed backwards
or oversized
Replace orice.
Flow blocked upstream
from run Clean out run or open
valve.
Loss of liquid in reference
leg (liquid level)
Rell reference leg.
Density changes in process
media or reference leg Rell reference leg with
same density liquid as
process media.
Primary element
to DPU piping
(refer to DPU
Manual)
Pressure tap holes plugged
and/or piping plugged Clean out piping.
Bypass valve open or
leaking
Close bypass valve(s)
and/or repair leaks.
Liquids or gases trapped in
piping Vent piping.
Block or shutoff valves
closed
Open block or
shutoff valves.
Piping leaks on HP side Repair leaks.
Low or no
Indication
(cont'd)
Bellows unit (refer
to DPU Manual) Housing lled with solids
restricting bellows movement
Clean out housing.
Gas (liquid service) or liquid
(gas service) trapped in
housing
Vent housing.
HP housng gasket leak Replace gasket.
DPU tampered with Return BUA for repair.
Indicator,
alarm switch
mechanism
Loose linkage or movement Tighten or replace.
Out of calibration Calibrate.
Pointer loose Tighten pointer.
Dirty or corroded mechanism Clean or replace.
Wiring interfering with move-
ment Re-route wiring.
Dirty mechanism Clean mechanism.
High
indication Primary source Orice partially restricted or
too small
Clean out or replace.
Primary element
to DPU piping Piping leaks on LP side Repair leaks.
Bellows unit
(Refer to DPU
Manual)
Gas (liquid service) or liquid
(gas service) trapped in
housing
Vent housing.
LP housing gasket leak Replace gasket.
Range Spring broken or
DPU tampered with
Return BUA for repair.

18
Table 3-1. Troubleshooting (cont'd)
Problem Possible Source Probable Cause Corrective Action
High
indication
(cont'd)
Indicator,
alarm switch
mechanism
Loose linkage or movement Tighten or replace.
Out of Calibration Calibrate.
Erratic
indication Primary element Flow pulsating M199 DPU – adjust
dampening;
All o hers – install
dampening device
upstream of DPU run.
Primary element
to DPU piping Liquid (gas service) or
gas bubble (liquid service)
trapped in piping
Remove.
Vapor generator incorrectly
installed
Re-pipe.
Reference leg gassy or
Liquid vaporizing
See piping instruc ions
in DPU Manual.
Bellows unit
(Refer to DPU
Manual)
Obstructed bellows travel Clean bellows.
Gas trapped in DPU HP or
LP housing
Remove (see Startup
procedure).
Linkage dragging or dirty Adjust or clean.
Pointer dragging on
scaleplate
Adjust pointer posi ion.
Inaccurate or
No Electrical
Alarm
Power supply Blown fuse Replace fuse.
Broken or loose wire Repair.
Alarm switch Switch not properly
adjusted
Adjust switch.
Dirty or burned Replace switch
contacts.

19
Figure 4-1. Model 289A Outside Dimensions (Part 1 of 2)
SECTION 4 - INSTALLATION/DIMENSIONAL DRAWINGS

20
Figure 4-2.
Model 289A
Outside Dimensions
(Part 2 of 2)
PRESSURE
RATING
PSI (MPa)
HOUSING
MATERIAL
PRESSURE
CONNECTION DIM. A
INCHES
(mm)
DIM. B
INCHES
(mm)
DIM. C
INCHES
(mm)
DIM. D
INCHES
(mm)
# BOLTS
TOP BOTTOM
1,000
(6.9)
CASTALUM. 356-T6 1/2 NPT
(Note 1) 1/4 NPT
(Note 1) 9-29/32
(251.6) 6-5/8
(168.3) 2
(50.8) 2-9/64
(51.2) 6
FORGED STNL. ST. 316 1/2 NPT
(Note 1) 1/4 NPT
(Note 1) 9-29/32
(251.6) 6-5/8
(168.3) 2
(50.8) 2-9/64
(51.2) 12
2,500
(17.2) FORGED ST. AISI C1018 1/2 NPT
(Note 1) 1/4 NPT
(Note 1) 10-5/32
(257.9) 7-1/8
(181.0) 2|
(50.8) 2-9/64
(51.2) 6
3,000
(20.7)
FORGED STNL. ST. 316 1/2 NPT
(Note 1) 1/4 NPT
(Note 1) 10-5/32
(257.9) 7-1/8
(181.0) 2
(50.8) 2-9/64
(51.2) 12
MONEL K500 1/2 NPT
(Note 1) 1/4 NPT
(Note 1) 10-5/32
(257.9) 7-1/8
(181.0) 2
(50.8) 2-9/64
(51.2) 12
4,500
(31.0) FORGED ALLOY ST 4142 1/2 NPT
(Note 1) 1/4 NPT
(Note 1) 10-5/32
(257.9) 7-1/8
(181.0) 2
(50.8) 2-9/64
(51.2) 12
6,000
(41.4)
FORGED ALLOY ST 4142
FORGED STNL ST 17-4 PH
9/16-18
UNF
(Note 2)
9/16-18
UNF
(Note 2)
10-5/32
(257.9) 7-1/8
(181.0) 2
(50.8) 2
(50.8) 12
FORGED ALLOY ST 4142
FORGED STNL ST 17-4 PH 1/2 NPT
(Note 1) 1/4 NPT
(Note 1) 10-5/32
(257.9) 7-1/8
(181.0) 2
(50.8) 2-9/64
(51.2) 12
Note 1: Can be reversed when ordered or can be rotated 180° in the eld.
Note 2: Suitable for use with Aminko ttings (American Inst. Co., Silver Springs, MD) or equiv.
Note 3: AlI standard pipe ttings furnished by customer.
Note 4: Cast alum. pipe mount supplied, unless otherwise specied. Specify pipe size when ordering threaded Stl.
adapter.
Metric conversions are approximate.
Table 4-1. Model 289A Dimensions (as shown in Figure 4-1, pg. 19)
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