IntroductionSWITZER Style 180 Differential Pressure indicator / switch isa rugged instrument featuring simplicity of design to providedependable and efficient service. Read instructions belowcarefully before installing the instrument.GeneralThe instrument is manufactured, checked and supplied inaccordance with our published specification, when installedand used in normal or prescribed applications with the lid inplace.Health and safety warningsa)Opening or dismantling when unit is live with respect to

ELECTRICAL OR PRESSURE will result in a hazard.b)Units must be selected and installed by suitably trained

and qualified persons in accordance with appropriatecodes of practice to avoid failure, injury or damage due tomisuse or wrong applications.

Note: The instrument is calibrated within the claimed accu-racy.. Therefore tampering of any component where there isred paint seal will lead to malfunctioningStorage– Storage temperature –10°C to +60°C.– In damp areas drying agents or heating is required against

formation of water condensation.Transport– Transport temperature –10°C to +60°C– Protect from external effects such as shock, vibration and

impact.Handling prior to fitting– Remove the plastic cover / protective cap just before the

installation.– Protect against effects of weather– Check the connection thread size to avoid mismatch of

pressure adaptor & pressure port.Mounting / Connections / Precautions1. Position gaskets and fix correctly at Terminal covers and

Bezel. Bezel mounting screws must be tight.2. Properly seal the electrical entries and cables with cor-

rect cable gland, weatherproof. If in doubt, consult factory.3. Do not exceed stated maximum working pressure & maxi-

mum temperature. The sensing element will be perma-nently damaged if exceeded EVEN ONCE.

4. Connected electrical load should not exceed stated maxi-mum electrical capacity in BOTH Amps and volts.

5. Do not establish pressure connections by rotating thehousing. Hold hexagon of the sensor pressure connector with suitable spanner and tighten.

6. Flush the pipe system before fitting. Ensure that no stressis produced and are sealed without leak.

7. Mount the instrument firmly and rigidly on a vibration freesurface, panel or pipe stanchion or wall. Connect withsuitable piping at appropriate pressure ports identifiedas HI & LO for High Pressure & Low Pressure respec-tively. The instruments are for vertical mounting, any tiltmay lead to inappropriate measurement.

8. For outdoor installation, provide protection against ag-gressive environment like very high or very low tempera-ture, dust,solar radiation, water penetration etc..

9. If process temperature is higher than the following per-missible maximum temperature it can be brought downby using longer pressure piping. Ask factory for pipingnomogram. For Elastomer Diaphragm operated Indicat-ing Switch, temperature limits are 120°C for Nitrile,130°C for EPDM (for Ammonia service) .,195°C forViton ., 200°C for Silicon .

10. For steam application use condensor coil or a syphon.

INSTRUCTION MANUAL FOR DP INDICATORS / DP INDICATING SWITCHES 180 MODEL11. For air and gas application, use proper filters (dust col-

lectors) to ensure that the process line is not cloggedwith accumulation of dust / foreign particles.

12. Ensure that suitable dampener / snubber is used in rap-idly fluctuating pressure to avoid chattering.

13. Vent or Drain periodically.OperationsThis instrument works on the difference between twopressures acting on opposite sides of the pressure sensor(diaphragm). Variations in pressure difference will causethe diaphragm-magnet assembly to move in proportion tothis change. A rotary magnet located in a separate cavityfollows the movement of the diaphragm magnet . A pointerattached to the shaft of this rotary magnet indicates thepressure change on the gauge scale. Since the pointermoves due to magnetic coupling there are no mechanicalseals between pressure side and gauge mechanism sideOn switching models, either microswitch or Reed switch islocated adjacent to the pressure chamber. W hen thediaphragm moves diaphragm driver magnetic field interactsat a pre-set point with magnet placed on the microswitchlever or directly actuates the reed switch armature.

To Change Switch SettingsFor Micro switch ( single switch only)Loosen the nut holding the micro switch. To increase the setpoint slide the switch towards the Low Pressure port side.To decrease set point move the switch towards the HighPressure port side. Repeat as required until the requiredsetting is attained. After setting re-tighten the nut.For Reed switch ( One or Two reed switches)In the case of two reed switches, they are adjustableindependently. Loosen the lock screw to move the switchassembly . To increase the set point slide the switch towardsthe Low Pressure port side. To decrease set point move theswitch towards the High Pressure port side. Repeat asrequired until the required setting is attained. After setting re-tighten the lock screw. When connected as in Fig 1, switchactuates on rising pressure / falling pressure accordingly.

Wiring Diagram for DPI with switching

Fig 1

(RED) NO at zero, closes on raising �P

(WHITE or GREEN) Common

(BLACK) NC at zero, opens on raising �PLOW

ALARM

HIGHALARM

Diaphragm Failure (Refer Fig.2 )This could occur through accidental overpressure abuse ormis-application. Remove the clamp between the dial housingand the pressure chamber. Then remove all M5 screws andremove the top half of the pressure housing (High Pressureport).Remove the Diaphragm and Area Plate assembly along withthe stem. Hold the stem in a vice or hold with a grip plierfirmly and unscrew the M4 screw on the top area plate. Ensurethat the magnet fixed at the bottom end of the stem is notdamaged while fixing the stem in the vice.Remove the damaged diaphragm and re-place with newdiaphragm on the bottom area plate. Position the top areaplate and tighten the assembly to the stem. Before insertingthe stem inside the body, ensure that the range spring isseated properly inside the spring locater. If not, theinstrument’s performance will be affected.Place the diaphragm assembly and high pressure chamberon the low pressure chamber and allign all screw holes andtighten all M5 screws. Position and tighten the dial clampwhich is provided to arrest inadvertent twisting motionbetween the Dial housing and the pressure housing.Hold the instrument with Vertical Dial and tap. Pointer shouldbe on zero and the new diaphragm acts only as a pressurebarrier with no spring effect. If the pointer is off zero slightly,loosen the guage clamp screw and slide pressure housinguntil pointer tip is at zero while holding the instrument dialvertical. After zero has been established tighten the clampscrew.If zero could not be established in the above manner, theninput a pressure exactly equal to 50% of the range. Use amaster guage with 1% or better accuracy to read the pressure.Remove the pointer and re-fix it at 50% of the scale. The zeroand the calibration will be established.Factory Setting: Even factory adjusted set points get shiftedin rare cases when consignments are badly handled duringtransit. When the user needs precise set point actuation, it isadvised to cross-check and re-adjust the set point with amaster gauge.

Servicing / MaintenanceThere are only two areas where this instrument requiresattention. One is erratic pointer action and the other isdiaphragm failure.

Caution :Do not position the indicator by turning or grasping thecase. Ensure that impulse pipework applies no stress onsensing element housing and use spanners to holdpressure port/ housing when connections are made.Thermal expansion of the pipe work must be taken up bycompensators.Do Not Remove the Pointer from its shaft, unless wa rrantedas the calibration reference will be lost.

Erratic Pointer ActionCheck to see if the pointer shaft lower trunnion bearing screwis in position. If the bearing screw is too far, it will grip thepivot shaft and produce uneven action or no displacement ofthe pointer at all. Bearing screw is located at the rear end ofthe pointer which is filled with rubber solvent. Adjust thebearing screw such that 0.8 mm (approx.) end play of thepointer shaft is established. After proper pointer action hasbeen re-established, seal the bearing screw using wax. Ifthe bearing screw has been found damaged, replace it.

General remarks on the operating instructionsAll the above guidelines on installation explained hereinshows how the instrument can be installed and operatedsafely.If difficulties arise, which cannot be solved with thisinstruction sheet and product information, contact factory.Switzer reserves all rights for making technical changes /improvements on a continual basis.

MountingThe Instrument is adapted for mounting as shown below:(a) Panel Mounting, (b) Pipe Mounting for 2" Pipe, (c) Wall /Surface.The instrument is supplied with a mounting bracket suitablefor both wall & 2" Pipe mounting.The instrument must be approximately leveled for properoperation.

Before doing maintenance, switch off power and removeswitch connection and turn off pressure tubing connected togauge.Remove tubing connections from gauge parts (by holdingthe pressure housing end cap with 26 inch spanner).Remove bezel screws, bezel, glass and glass gaskets.Inspections should be carried out at quarterly to yearly inter-vals depending upon operating conditions.Isolate unit from process and power and remove lid. Checkterminals for tightness.Check that cable tails are not fouledor chafed. Check for internal condensation and rectify.It is recommended that the instruments are checked for cali-bration/operation once a year. However, in critical applica-tions, switch is to be operated and checked more frequentlyto ensure correct functioning.Instruments are so designed with rugged components thatthey seldom require maintenance. Occasional cleaning ofmoving parts, checking of the switch(s) and ensuring firmelectrical contacts at the terminals will provide a long trouble-free performance.Process lines are to be periodically checked for accumula-tion of dust / foreign particles to avoid clogging. Cloggingwould render the instrument non-functioning as the sensingelement shall not have free movement during pressure fluc-tuations.

Fig 2

M5 SCREW & NUT

AREA PLATEHOLDING SCREW

HIGH PORT

AREA PLATE

DIAPHRAGM(REPLACEABLE)

SPRING LOCATER

BEARING SCREW

LOW PORT

IM–1

80 R

ev.3

A (0

915)Switzer Process Instruments Pvt. Ltd.Switzer Process Instruments Pvt. Ltd.Switzer Process Instruments Pvt. Ltd.Switzer Process Instruments Pvt. Ltd.

REGD. OFFICE : 128, Sidco North Phase, Ambattur Estates, Chennai 600 098.

PH: 044– 26252017 / 26252018 FAX: 044–26248849E-MAIL: works@switzerprocess.co.in; sales@switzerprocess.co.in

WEB-SITE: www.switzerprocess.co.in