current meter maintenance model osspc1 hydrographic training bandar seri begawan brunei august 2010

Current Meter Maintenance Model OSSPC1

Hydrographic TrainingBandar Seri Begawan

BruneiAugust 2010

• Ensures that induced errors in measurement from ‘mechanical’ sources are eliminated

• Prolongs life of current meter and components

Why Is This Important?

Section 1Prior to Gauging

Procedure

Important Points• Dispose of used current meter oil in a thoughtful

manner

• Place components on lint free cloth or paper

• Ensure components do not come into contact with dust

• Use ONLY approved HS current meter oil (PYG-17)

Spin Test

• Prior to spin test hold the current meter in the horizontal position, with fan facing directly to your mouth

• Blow air forcefully and allow fan to spin for approx. one minute (to minimise any hydraulic pressure )

DO NOT SPIN BY HAND

Spin Test

• Spin test the meter against time (as per table shown)

• Connect current meter to the counter and test operation

Fan No. Minimum Time (secs)

1 36

3 13

5 11

Fan No. Minimum Time (secs)

1 40

3 15

5 13

Shaft Diameter 4.0mm

Shaft Diameter 2.5mm

Section 2During and After Discharge

Measurements

General Rule

After every discharge measurement, (or one hour of use), the current meter should be disassembled, cleaned, re-filled with oil and reassembled, if continuing a discharge measurement.

Procedure

• Remove fan from meter shaft and dispose of used oil from meter body

• Disassemble meter as shown in Section 1

• Undo the cleaning jar cap and ‘¾ fill’ with white spirit

• Place components on lint free cloth or paper (do not place in contact with dirt particles)

• Place shaft in cleaning jar and agitate in order to flush out used oil

• Fill body of meter with white spirit, place thumb over opening and shake

• Empty and dispose of white spirit from meter body

After Discharge Measurements

• Refill with oil if continuing a gauging

• Blow dry the shaft assembly, fan carrier and fan.

• Assemble ‘dry’ if meter going into storage

After Discharge Measurements

• Spin test the current meter against time as shown in Section 1

• After the spin test is performed connect your current meter to the counter using the lead, to test the lead, reed switch and counter.

Section 3Office Service

When?

• Once per month (if current meter is used regularly (daily?)

• Use same procedure described under Section 2

How?

Section 4Calibration

Calibration• •         Re-calibrate the current meter every 300 hours

of use or once a year which ever comes first (see Hydrological Services calibration certificate for

details)

• •         To minimise freight costs, send only the body and fans requiring re-calibration

Note: Hydrological Services provides a re-calibration and repair service for all types of current meters.

Section 5Troubleshooting

SYMPTON POSSIBLE CAUSES

ACTION REMARK

Failed spin test Dirty bearingsFaulty bearings

Clean bearingsReplace bearings if problem persists

If fan stops suddenly towards end of spin test, likely cause is dirty bearings

Failed spin test Bent shaft If shaft is bent, return to HS for repair or replace with new shaft

Bent shaft can be observed by looking directly at point of fan during a spin test. If this point is turning ‘off centre’, shaft is bent

Fan out of balance Fan squashed or dropped

Remove the fan, rotate the shaft approx. 50° and re-fit the fan on to the shaft. If problem persists return the fan and body to HS for repair

If fan stops and rotates in opposite direction at end of spin test, this indicates that the fan is out of balance

MECHANICAL PROBLEMS

SYMPTON POSSIBLE CAUSES ACTION

Fault occurs only when meter is immersed in water

Water entering contact plug receptacle and earthing between body and plug

Replace damaged plug (see manual)

Circuit closed in any magnet position, but open with magnet removed

Reed switch failed Replace reed switch assembly

Circuit closed without magnet in position

Reed damaged Replace reed switch assembly

ELECTRICAL PROBLEMS (Closed Circuit Fault)

SYMPTON POSSIBLE CAUSES ACTION

Open circuit between plug and insulated reed contact

Faulty plug contact Clean contact in plugRe-test

Open circuit between plug and insulated reed contact

Faulty insulated contact assembly

Replace

No closure of reed switch contact when magnet in position

Damaged reed Replace

ELECTRICAL PROBLEMS (Open Circuit Fault)

Questions?