Current Meter Maintenance Model OSSPC1 Hydrographic Training Bandar Seri Begawan Brunei August 2010

Ensures that induced errors in measurement from ‘mechanical’ sources are eliminated Prolongs life of current meter and components Why Is This Important?

Section 1 Prior 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) Fan No.Minimum Time (secs) Shaft Diameter 4.0mm Shaft Diameter 2.5mm

Section 2 During 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 3 Office Service

When? Once per month (if current meter is used regularly (daily?) Use same procedure described under Section 2 How?

Section 4 Calibration

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 5 Troubleshooting

SYMPTONPOSSIBLE CAUSES ACTIONREMARK Failed spin testDirty bearings Faulty bearings Clean bearings Replace bearings if problem persists If fan stops suddenly towards end of spin test, likely cause is dirty bearings Failed spin testBent shaftIf 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 balanceFan 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

SYMPTONPOSSIBLE CAUSESACTION 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 failedReplace reed switch assembly Circuit closed without magnet in position Reed damagedReplace reed switch assembly ELECTRICAL PROBLEMS (Closed Circuit Fault)

SYMPTONPOSSIBLE CAUSESACTION Open circuit between plug and insulated reed contact Faulty plug contactClean contact in plug Re-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 reedReplace ELECTRICAL PROBLEMS (Open Circuit Fault)

Questions?