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5.3 Estimate zinc anode replacement intervals
The mass and surface area of the zinc anodes are designed to protect the pump surface for
1 year in sea water with an average temperature of 20°C (68°F). Shorter inspection intervals
and anode replacement can be required, depending upon the water temperature and the
chemical composition as well as the presence of other metals in the vicinity of the pump.
The rate of zinc consumption, and the appropriate inspection intervals, can be estimated by
measuring how much zinc is consumed during the first two months following installation.
Anodes are replaced when the anode mass is reduced to a selected fraction of its initial
mass. The recommended interval for the selection fraction is 0.25–0.50 (25–50%).
1. Remove, weigh, and reinstall one or more of the exterior zinc anodes before starting up
the pump.
2. After two months, remove and weigh the same zinc anode or anodes again.
3. Divide the lapsed time in days (between steps 1 and 2) by the anode weight loss in
grams to get the calculated anode consumption rate (days/gram).
If multiple anodes were weighed, then use the anode which has lost the most weight for
this calculation.
4. Calculate future replacement intervals so that they occur when the selected fraction of
zinc is remaining.
5.4 Start the pump
CAUTION: Crush Hazard
The starting jerk can be powerful. Make sure nobody is close to the unit when it is started.
1. Check that:
a) The monitoring equipment works.
b) The starter equipment is installed according to the instructions from the manufacturer.
c) All the alarms function.
d) The lubricant is at the correct level.
2. Remove the fuses or open the circuit breaker, and check that the impeller can be rotated
freely.
Make sure that the propeller rotates in the correct direction. See
rotation
3. Conduct insulation test phase to ground. To pass, value must exceed 5 megohms. See
Checking insulation and sensors
4. Start the pump.
Check that:
• The machine works without noise or vibration.
• All electrical values are correct.
• All accessories work correctly.
Record any abnormalities.
P7900 Installation, Operation, and Maintenance Manual
WARNING: Crush Hazard
Never put your hand into the pump housing.
on page 42.
.
5 Operation
Check the impeller
45
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