Cameron BARTON 580A, BARTON 580A-0 User Manual

BARTON® NUCLEAR MODEL 580A

DIFFERENTIAL PRESSURE

SWITCH

User Manual

Part No. 9A-C10795, Rev. 03

September 2015

Model 580A-0 Switch
with Indicator

Contents

Safety ............................................................................................................ 2

Section 1—Introduction ................................................................................. 3

General ......................................................................................................... 3

Wiring ........................................................................................................ 5

Differential Pressure Unit (DPU) ............................................................... 5

Specications ............................................................................................... 6

General...................................................................................................... 6

Nuclear Qualications ............................................................................... 6

Application Specications ......................................................................... 7

Storage Specications .............................................................................. 7

Section 2—Installation ................................................................................... 9

Mounting/Piping/DPU Installation ................................................................. 9

Electrical Connection .................................................................................... 9

Switch Use .................................................................................................... 9

Startup ........................................................................................................ 10

Switch Wiring .............................................................................................. 10

Section 3—Maintenance and Calibration ....................................................11

Tools............................................................................................................ 12

Bezel/Lens Assembly or Cover Installation and Removal........................... 12

Pointer Installation and Removal ................................................................ 13

Pointer Installation .................................................................................. 13

Pointer Removal ...................................................................................... 14

Scale Plate Installation and Removal ......................................................... 14

Indicator Calibration .................................................................................... 15

Drive Arm Tightness Test ......................................................................... 17

Drive Arm Stop Adjustment ..................................................................... 17

Switch Calibration ..................................................................................... 18

Calibration Setup ..................................................................................... 18

Linkage Calibration Procedure ............................................................... 19

Safety

Before installing this product, become familiar with the installation instruc­tions presented in Section 3, Appendix A and all safety notes throughout.

!

 WARNING:Thissymbolidentiesinformationaboutpracticesorcircum-

stancesthatcanleadtopersonalinjuryordeath,propertydamage,or

economic loss.

CAUTION: Indicatesactionsorprocedureswhichifnotperformedcorrectly

mayleadtopersonalinjuryorincorrectfunctionoftheinstrument
orconnectedequipment.

IMPORTANT: Indicates actions or procedures which may affect instrument operation or

may lead to an instrument response that is not planned.

Changing Switch Set Point ......................................................................... 20

Denitions of Terms ................................................................................. 20

Best Practices for Set Points ................................................................... 20

Changing Set Point of an In-Service Instrument (Not Recommended for

Nuclear Qualied Units) .......................................................................... 21

Changing Set Point of an Out-of-Service Instrument .............................. 22

Range Changes ...................................................................................... 22

Troubleshooting ......................................................................................... 23

Section4—AssemblyDrawingandPartsList ........................................... 25

Section5—DimensionalDrawings ............................................................. 33

AppendixA—Model224DPU ....................................................................A-1

DPU Description ........................................................................................A-1

Specications .........................................................................................A-1

Theory of Operation ...............................................................................A-3

DPU Installation .........................................................................................A-4

General...................................................................................................A-4

Mounting.................................................................................................A-5

Piping .....................................................................................................A-5

Piping Diagrams .....................................................................................A-6

Startup ..................................................................................................A-12

DPU Maintenance ....................................................................................A-12

DPU Cleaning and Inspection ..............................................................A-13

Changing the DPU Range ....................................................................A-14

Replacing the Bellows Unit Assembly (BUA) .......................................A-14

DPU Troubleshooting ...............................................................................A-15

DPU Assembly Drawing and Parts List ....................................................A-17

DPU Dimensional Drawing ......................................................................A-19

3

Model 580A Differential Pressure Switch Section 1

Section 1—Introduction

General

The 580A Differential Pressure Switch actuates single or dual signal circuits

when predetermined limits of ow or level are exceeded. The DPU is con­nected to the process or vessel by tubing or piping. Changes in differential
pressure (DP) at the DPU produce a mechanical output which moves a pointer

and switch actuation controls.

For ow measurements, the instrument is connected to the high-pressure
and low-pressure sides of a primary device in the process run. Normally the
primary device will be an orice plate, venturi, or ow tube.

For liquid level measurement applications, the instrument is connected to
measure changes in differential pressure caused by variations in hydrostatic

pressures of the liquid in a tank.

The 580A switch is available in three model variations:

• Indicating Switch (Model 580A-0). This model, shown on the manual
cover, has a thick tempered plate glass lens and provides a visual indica­tion of the difference in the two monitored pressures.

• Blind Switch (Model 580A-2).This model has a solid metal cover and

provides no visual indication of differential pressure.

• Blind Switch with Internal Indicator. Unlike the indicating model with
the glass lens, there is no externally visible indicator. However, internally,
components are the same as in Model 580A-0. With the cover removed, a
user can use the internal indicator to determine DPU input pressure when

making adjustments to the switch setpoints.

The Model 580A uses two independently adjustable single-pole double-throw
(SPDT) snap-acting switches that are rated for high temperatures. Both sides

of the switches are wired, enabling the switches to serve both normally-open

and normally-closed applications. The direct-set switch contacts are adjustable

over a scale range of 10-90% nominal. Switches and all adjustments are read­ily accessible when the cover is removed (see Figures 1.1 and 1.2, page 4).

The 580A Switches (indicating and blind) are qualied per IEEE 323-1974,
IEEE 344-1975, IEEE 381-1977and NUREG 0588, Rev. 1 for either Func­tional and/or Pressure Boundary Integrity service in limited harsh environ-

ment applications.

The switch case is drawn stainless steel with a sealed glass header for the

electrical interface with the switches. No additional conduit seals are required

to ensure the integrity of the instrument.

4

Section 1 Model 580A Differential Pressure Switch

Left Switch

Right Switch

Pointer

Left Switch
Lock Screw

Plunger Screw

Actuating Cam

Left Switch
Adjustment
Assembly*

Switch Adjust Linkage

Plunger Screw

Right Switch
Lock Screw

Drive Arm

Stop Bracket

Movement Assembly

Terminal Strip

Switch Adjust Linkage

Right Switch
Adjustment
Assembly*

Range Adjust

* Switch Adjustment Assembly includes crank, index shaft, and index pointer.

Figure 1.1—580A (with indicator), internal components

Left Switch

Right Switch

Left Switch
Lock Screw

Plunger Screw

Actuating Cam

Left Switch
Adjustment
Assembly*

Switch Adjust Linkage

Plunger Screw

Right Switch
Lock Screw

Terminal Strip

Switch Adjust Linkage

Right Switch
Adjustment

Assembly*

Cam Actuator

* Switch Adjustment Assembly includes crank, index shaft, and index pointer.

Figure 1.2—580A (without indicator), internal components

The cam rotates counterclockwise with increased pressure. In Figure 1.3, page

5, the LOW switch (typically set to alarm at decreasing pressure) is set at 25%

differential pressure while the HIGH switch (typically set to alarm at increas­ing pressure) is set at 75% differential pressure.

5

Model 580A Differential Pressure Switch Section 1

1000

50

Zero DP

1000

50

Maximum DP

RED

Y ELLO W

BLUE

BLAC K

GREEN

WHITE

1000

50

SWI TCH "A"

(LEF T)

SWI TCH "B"

(RI GHT)

CAM

TERMI NAL
BLOCK I N

CASE

BOT H SW ITC HES RELAX ED

SWI TCH

P

LUNGER

SCREW

Mid-point DP

HIGHLOW

SWI TCH "A" AC TU AT ED/SW ITC H "B" RELAX ED

SWI TCH "A" RELAX ED/ SW IT CH "B" AC TU AT ED

SWITCH

CLOSED

CONTA CTS

OPEN

CONTA CTS

GREEN/W HITE GREEN/BLA CK

A (LEFT)

B (RIGHT)

YELLOW/BLUE YELLOW/RED

SWITCH

CLOSED

CONTA CTS

OPEN

CONTA CTS

GREEN/W HITE GREEN/BLA CK

A (LEFT)

B (RIGHT)

YELLOW/RED YELLOW/BLUE

SWITCH

CLOSED

CONTA CTS

OPEN

CONTA CTS

GREEN/W HITEGREEN/BLA CK

A (LEFT)

B (RIGHT)

YELLOW/BLUE YELLOW/RED

SWI TCH "A"

(LEF T)

SWI TCH "B"

(RI GHT)

SWI TCH "A"

(LEF T)

SWI TCH "B"

(RI GHT)

Notes:

1. CAM ROTATES COUNTER-CLOCKWISE WITH INCREASED DIFFERENTIAL PRESSURE

2. EACH SWITCH MAY BE SET AT ANY POINT FROM 10% TO 90% OF DP RANGE

3. WIRES: No. 22 AWG (Internal) and No. 18 AWG (External)

Figure 1.3—Switch wiring connections and actuation example

Wiring

Each switch is wired internally to a glass-sealed header using No. 22 AWG
ethylene tetrauoroethylene (Tefzel®) insulated wire for radiation service per
IEEE Standard 393-1974. Externally, from the header, permanently color
coded No. 18 AWG Tefzel® wires exit through a female conduit connection.

Differential Pressure Unit (DPU)

For detailed information on the Model 224 DPU, see Appendix A, page A-1.

6

Section 1 Model 580A Differential Pressure Switch

Specications

General

Actuating Unit (DPU) ...................... Model 224 DPU

Dial Size ......................................... 6 inches (150 mm)

Service Conditions (Normal)........... 40°F (4.4°C) to +180°F (+82.2°C) @ <90% R.H.

Switch Repeatability ....................... ±1% of calibrated span

Switch Set-point Range .................. 10 to 90% of calibrated span

Switch Deadband ........................... ±10% of calibrated span (maximum)

Switch Type .................................... Mechanical, Snap-Acting; both switches are SPDT

Activation ........................................ Increasing or decreasing scale

Switch Contact Rating:

5.0 Amps @ 125 VAC

5.0 Amps @ 250 VAC

3.0 Amps @ 30 VDC (resistive)

1.0 Amp @ 30 VDC (inductive w/arc suppression)

0.4 Amp @ 125 VDC (resistive)

0.2 Amp @ 125 VDC (inductive w/arc suppression)

Input Range .................................... 0-30" WC to 0-650 psid

Indicator Accuracy .......................... ±2.0% of calibrated span (for ranges to 400 psid)

1,2

Indicator Repeatability .................... ±0.5% of calibrated span

Safe Working Pressure ................... 500, 1000, 1500, 3000, or 6000 psig

Maximum Overrange ...................... To safe working pressure

Process Connections...................... 1/4" x 1/4", 1/4" x 1/2", 1/2" x 1/4" and 1/2" x 1/2"

(top x bottom)

Electrical Connections .................... Female, 3/4" NPT, 20 ft., color-coded Tefzel®

insulated 18 AWG wire (40 ft. leads available by
special order)

Torque Tube Rotation ..................... 8° (nominal)

1

± 2.5% of calibrated span for ranges between 400 and 600 psid; ±6% for ranges over

600 psid.

2

Additional 2% is applicable near the switch setpoints (±10% span).

Nuclear Qualications

The following nuclear qualication applications are based on Cameron Engi­neering Report 9A-CR3-580A-29 and 9A-CR3-580A31.

Design Basis Event (DBE) Performance Error1 (% of calibrated span):

Radiation (1 x 107 Rads) ................ ±10%

Seismic (12.5 Gs):

During Event ................................... ±10%

Following Event .............................. ±5%

Harsh Environment (≤ 200°F):

During Event ................................... ±10%

Following Event .............................. ±10%

1

Includes the cumulative effect of accelerated aging.

7

Model 580A Differential Pressure Switch Section 1

Application Specications

Model 580A switches were subjected to IEEE 323-1974/344-1975 quali­cation testing, which found the devices suitable for functional service in a
limited harsh environment. The service conditions associated with the limited
qualications are:

• 22 year qualied service life1 normal conditions of 104°F and 0 psig

• Radiation exposure to 1 x 107 Rads (TID)

• 85 days @maximum DBE conditions of 200°F, 10 psig ambient pressure

and ≥ 95% R.H.

• Seismic qualications:

– OBE @ 6.25 Gs (series of 5)
– SSE @ 12.5 Gs
– 5% critical damping
– No resonance in frequencies below 33 Hz

• Mechanical aging included:

– 25,000 pressure cycles during accelerated aging
– 12,500 electrical cycles during accelerated aging
– Vibration cycling using 0.2 G sinusoidal sweeps over the 1 to 200

Hz range at 1.0 octave/min.

1

Qualied Life: This equipment contains some organic material. The qualied life will be

governed by factors such as environmental temperature, radiation exposure, and activa­tion energy.

Storage Specications

Storage per ANSI N45.2.2-1978 Level B at 70°F (21°C) ±20°F (±11°C) in
factory sealed package for 2.5 years maximum will not affect installed service

life.

8

Section 1 Model 580A Differential Pressure Switch

9

Model 580A Differential Pressure Switch Section 2

Section 2—Installation

The instrument should be inspected at time of unpacking to detect any dam-

age that may have occurred during shipment.

IMPORTANT: The DPU was checked for accuracy at the factory. Do not change any of

the settings during examination or accuracy could 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.

Mounting/Piping/DPUInstallation

Mount the instrument with four customer-supplied 5/16-in. (8-mm) bolts,
Grade 5 or greater, torqued to 17 ft/lbs. Mounting structures should be
designed to avoid resonance and/or minimize resulting amplication below
33 Hz. Response spectra at mounting surface of the instrument shall not
exceed those in the R3-580A-29 Qualication Report. Interfacing process

tubing and conduit shall be supported by the same mounting as the DP instru-

ment base in order to minimize relative motion of the DP instrument and

connections.

Dimensional drawings are provided on Section 5—Dimensional Drawings,

page 33.

See Appendix A, page A-1, for Model 224 DPU installation and mainte-
nance information.

Electrical Connection

Units are supplied with dual alarm switches. The direct-set switch contacts
are adjustable over 10% to 90% of the scale range.

The high switch and low switch set point adjustment procedures are covered

in Changing Switch Set Point, page 20.

For physical location of switches, see Figures 1.1 and 1.2, page 4.

SwitchUse

Switch contact life is inuenced by various application conditions such as
temperature, 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.

10

Section 2 Model 580A Differential Pressure Switch

IMPORTANT: Arc suppression for inductive loads will prolong the life of the switch

contacts.

Startup

For startup procedures, warnings, and other information on the Model 224

DPU, see Appendix A, page A-1.

IMPORTANT: To ensure the unit calibration is within factory-set calibration tolerances,

perform the Calibration Check procedure on page 12.

SwitchWiring

IMPORTANT: Figure 2.1 shows switch contacts in the relaxed (shelf) condition, the low

switch set to trip at a position below the pointer scale position, and the
high switch set to trip at a position above the pointer scale position. NO
= Normally Open in (shelf) condition. NC = Normally Closed in (shelf)
condition. C= Common.

LOW & HIGH SPDT SWITCHES

NO NOC CNC NC

RED

YELLOW

BLUE

RED

YELLOW

BLUE

WHITE

GREEN

BLACK

WHITE

GREEN

BLACK

1 2 3 4 5 6 7 8 9 10

Figure 2.1—Low/high SPDT switch diagrams

Table2.1—SwitchWireColorCoding

580ACurrentCongurations

NO C NC

Low Red Yellow Blue

High Black Green White

11

Model 580A Differential Pressure Switch Section 3

Section 3—Maintenance and Calibration

The following checks are recommended for preventive maintenance:

• Periodically inspect the alarm switch mechanism to verify that all mount­ing screws are seated properly.

• Inspect linkage for wear.

• Inspect integrity of electrical circuits. Tighten as necessary.

When repairs are necesssary, review this section for maintenance procedures
such as bezel/lens installation and removal, pointer installation and removal,
indicator calibration, switch calibration, and switch set point changes. Refer
to Figure 3.1 as needed for component identication.

SWITCH LOCKS

ZERO ADJUST

POINTER STOP

3/4 NPT (INTERNAL)
CONDUIT CONNECTOR
20 FT (6.1 M) LG
18 AWG EXT LEADS STANDARD;

40 FT (12.2 M) LG LEADS OPTIONAL

SWITCH ADJUST 1/8 (3.2)
HEX 1/8 DP

TO ADJUST SWITCH SETTING

REMOVE SCREWS AND COVER

RANGE ADJUST

POINTER

Figure 3.1—Model 580A adjustment controls

IMPORTANT: Never perform maintenance/repair on the Model 580A differential pres-

sure switch without rst reviewing all procedures and warning/caution

notices in this manual. See Appendix A, page A-1, for related warning/
caution notices and instructions for the Model 224 DPU.

12

Section 3 Model 580A Differential Pressure Switch

Tools

The following tools are recommended for general maintenance of the Model
580A differential pressure switch.

Table 3.1—Tools

Equipment Purpose

Pointer Puller Pointer removal

Small Screwdriver Calibration adjustment

Medium Screwdriver Bezel removal and replacement

1/4" and 1/8" Open-end Wrenches Zero (1/4") and Range (1/8") adjustments

1/8 Hex Allen Wrench Switch set point adjustment

Bezel/LensAssemblyorCoverInstallationandRemoval

To remove the bezel/lens assembly or cover, loosen the eight screws on the
front and lift the assembly or cover from the enclosure.

To reinstall the bezel/lens assembly (580A-0 only), install the O-ring in the
groove of the case, assemble the bezel, lens, and lens gasket, and realign the
screw holes with the holes in the case. Then, reinstall the screws in the bezel

to secure all components to the case. Torque the screws per Table 4.3, page

31.

To reinstall the cover (580A-2), install the O-ring in the groove of the case
and realign the screw holes in the cover with the holes in the case. Reinstall
the screws in the cover to secure it to the case. Torque the screws per Table

4.3, page 31.

Calibration Check

To ensure the unit calibration is within factory-set calibration tolerances,
perform the following procedure.

IMPORTANT: Review all Model 224 DPU procedures and WARNINGS/NOTICES in

Appendix A, page A-1, before performing this procedure.

1. Mount the instrument in an approximately level position and connect to a

standard pressure source.

2. If the zero indication is incorrect, adjust it as follows:
a. Remove the bezel/lens assembly or cover.
b. Using a 1/4" open-end wrench (included in calibration toolkit, Part

No. 9A-0288-1032B), hold the hexagon pointer hub xed and rotate
the pointer with ngers until the pointer indicates zero on the scale.

See Figure 3.2, page 13.

13

Model 580A Differential Pressure Switch Section 3

c. Replace the bezel/lens assembly.

HUB

Pointer "slipped"
rotated on hub

Hub held in place
with 1/4" wrench

Figure 3.2—"Slipping" pointer

3. To test for reverse travel, connect the pressure source to the low-pressure
(LP) housing and vent the HP housing. Apply pressure to approximately
150% of the DP range. The pointer should move approximately 5% to
10% below zero.

4. To test for overtravel, connect the pressure source to the HP housing and
vent the LP housing. Apply pressure to approximately 150% of DP range.
The pointer should move approximately 5% to 10% above the full scale

mark.

5. Apply 0, 50, and 100% of full scale pressure. If the indication is within

specied limits, no adjustments are necessary. If the indication is not
within specied limits, perform a complete calibration (see Indicator

Calibration, page 15).

6. Make sure the instrument zero indication is correct; otherwise, repeat

step 2.

7. Verify the switch set points (refer to Changing Switch Set Point, page

20).

PointerInstallationandRemoval

During adjustment and calibration of the unit, it may be necessary to remove
and reinstall the pointer. See the following procedures for instructions. Note
that the scale plate is split to allow it to be removed without pulling the

pointer.

Pointer Installation

1. Position the pointer on the movement shaft with the pointer set at zero
scale. Obtain 75% to 90% pointer hub engagement on the movement

pinion shaft. The pinion shaft must not extend through the pointer hub. It
may be necessary to enlarge the hub hole using a tapered broach (includ-

ed in the calibration toolkit, Part No. 9A-0288-1032B).

14

Section 3 Model 580A Differential Pressure Switch

2. Lightly tap the pointer hub with a hand-set or other at-end tool. Use
perpendicular blows to avoid bending the shaft.

3. Check the calibration of the indicating switch over its entire range (refer
to Indicator Calibration, page 15). If the indicating switch is correctly

calibrated, secure the pointer to the movement shaft by tapping the hub
with a hand-set or other at-end tool.

4. Test the pointer for tightness by moving the pointer from the zero to the
50% position manually, and then letting the pointer return freely to zero.

If the pointer indicates a shift, tap the pointer hub to tighten it to the
shaft.

Pointer Removal

The pointer is removed with a pointer puller shown in Figure 3.3. This tool is
included in the calibration toolkit, Part No. 9A-0288-1032B.

To remove the pointer, perform the following steps:

1. Slide the pointer puller along the pointer until the pin protruding from the
tip of the screw in the pointer puller is directly over the movement shaft

and the arms of the pointer puller are directly under the pointer.

2. Gently turn the knurled head of the screw clockwise, pushing the pin

against the movement shaft and lifting the pointer with the arms. Finger
pressure should be sufcient to pull the pointer free. If more pressure is

required, an Allen wrench (inserted into head of the screw) can be used.

However, care should be exercised to avoid breaking the pin.

HUB

MOVEMENT SHAFT

POINTER

HUB

POINTER PULLER

Figure 3.3—Pointer puller (Part No. 9A-0163-0005B)

ScalePlateInstallationandRemoval

During adjustments and calibration of the unit, it may be necessary to remove
and reinstall the scale plate. The scale plate is split to allow removal without
pulling the pointer. It is held in place by ve screws (Item 40 in Figure A.1,

page A-2) and two mounting tabs at 12 o'clock and 6 o'clock positions. The

scale plate halves rest against the top tab (12 o'clock), and slide beneath the
bottom tab (6 o'clock).

15

Model 580A Differential Pressure Switch Section 3

To remove the scale plate, move the pointer to the 12 o'clock position, remove
the screws from the scale plate, and gently guide the scale plate halves from
beneath the bottom mounting tab. Screws are located at 12, 3 and 9 o'clock
positions and near the center of the plate which overlays a narrow bracket.

To reinstall the scale plate, repeat the installation steps in reverse order, as
follows. Holding the pointer in the 12 o'clock position, place the scale plate
halves against the top mounting tab and guide the bottom edges behind the
bottom tab. Replace the screws in the top tab and in the center of the scale
plate. No screw is used with the bottom tab.

Indicator Calibration

If the DPU assembly is replaced on a Model 580A differential pressure switch

with indicator, the indicator must be recalibrated. This procedure does not ap­ply to the 580A-2 blind switch without indicator.

IMPORTANT: Review all Model 224 DPU procedures and WARNINGS/NOTICES in

Appendix A, page A-1, before performing this procedure.

1. Securely mount the instrument in an approximately level position and
connect the DPU, as described in Mounting, page A-5.

2. Remove the bezel/lens assembly or cover.

3. Align the linkage between the drive arm and the movement at 50% differ­ential pressure (DP) as shown in Figure 3.3. Inspect parts for straightness

and pivot-t without binding.

Figure 3.4—Range/linearity adjustment (50% DP)

4. Check the pointer for zero indication. If necessary, set the pointer to zero
by slipping the pointer on the hub, per step 2 of Calibration Check, page

12.

5. Apply 100% pressure. If the pointer exceeds full-scale, adjust the range
adjust screw with a 1/8-in. open-end wrench to lengthen the movement

range arm..

16

Section 3 Model 580A Differential Pressure Switch

6. Release pressure. Set the pointer to zero, by slipping the pointer on the

hub, per step 2 of Calibration Check, page 12.

7. Repeat steps 4 and 5, as necessary, to obtain the correct zero/full-scale.

8. Apply 50% DP. If the pointer indicates 50%, proceed to step 9. If the
pointer does not indicate 50% scale, adjust linearity as follows.
a. Loosen the drive arm screw (Figure 3.5) and move the arm to shift

the pointer in the direction of the error a distance of about 10 times

the linearity error.

b. To prevent interference, check to see that the drive arm clears the

end of torque-tube housing by approximately 0.030 in. before re-

tightening the drive arm screw.

c. While supporting the block/shaft, tighten the clamp screw until it is

snug to the shaft.

d. Still supporting the block/shaft, tighten the clamp screw an addition-

al 1/3 to 1/2 turn. (This screw can normally turn one full revolution

before breaking.)

e. Perform the Drive Arm Tightness Test described on page 17 before

returning the instrument to service.

1/8” WRENCH

(PN 9A-0163-0044C)

CLAMP SCREW

DRIVE ARM

LINK

SINTERED

CLAMP BLOCK

TO TIGHTEN

.03 (approx)

M224

SHAFT

Figure 3.5—Drive arm to torque tube connection

9. Release pressure and reset the pointer to zero. Check the span. If the gear
in the movement reaches a limit of travel as a result of linearity adjust-

ment (step 8), slip the range arm along the gear approximately 5 degrees

from the normal 37.5 degree angle to approximately 43 degrees (see

step 3). To slip the range arm, apply pressure to the range arm with the

thumb, while holding the gear rmly in place. Retest the pointer response
at 50%, 0%, and 100% of full-scale differential pressure, and adjust the

linkage until the readings are acceptable.

17

Model 580A Differential Pressure Switch Section 3

10. Apply 0%, 25%, 50%, 75%, 100%, 75%, 50%, 25%, and 0% of full-scale
differential pressure consecutively to the instrument without overshoot.
Lightly tap the indicator to overcome friction. The pointer should accu-

rately indicate each applied pressure.

11. Test the instrument repeatability by applying 0%, 50%, 0%, 50% of full-

scale differential pressure. The indicator should accurately indicate each
applied pressure.

12. Set the drive arm stop to prevent the pointer from striking the post lock

on the scale.

13. Test the pointer for tightness per the pointer installation instructions on

Pointer Installation, page 13.

14. If the drive arm screw has been loosened, check for tightness by perform­ing the Drive Arm Tightness Test described below.

15. Reassemble the unit per the cover installation instructions on Bezel/Lens

(or Cover) Installation and Removal, page 12.

Drive Arm Tightness Test

This procedure tests the tightness of the drive arm's connection to the torque
tube by applying torque developed by the DPU onto a xed drive arm. Ap-

ply pressure slowly, as torque is being applied to the connection through the

torque tube drive shaft.

1. With the pointer at normal 0% torque tube rotation position (0% on a
normal 0 to 100% scale unit), adjust the drive arm stop bracket (or use
alternate means) to prevent the pointer from moving (the stop bracket
interferes with drive arm movement).

IMPORTANT: On reverse acting/split range units, it will be necessary to pressurize the

DPU to move the pointer to the minimum scale position. On suppressed
units, it will be necessary to apply pressure to establish a reference point
to check for "zero" shift.

2. Pressurize the DPU to full scale DP (100% of full scale range) to apply 8
degrees of equivalent torque to the connection.

3. Observe the shift in the "zero" indication following DPU depressuriza­tion (as required) and drive arm stop bracket readjusting (to allow free
movement of drive arm and pointer). A downscale (counter-clockwise)
shift in "zero" of greater than 1/2% indicates drive arm slippage, neces-

sitating further clamp block tightening.

Drive Arm Stop Adjustment

1. Apply sufcient pressure to the high-pressure housing to deect the

pointer against the full range post lock on the scale plate.

2. Slide the upper drive arm stop bracket against the drive arm and tighten

the drive arm stop bracket screw.