Zinc Anode Electrical Continuity Check; Zinc Anode Replacement - Teledyne WORKHORSE Operation Manual

WorkHorse H-ADCP Operation Manual

Zinc Anode Electrical Continuity Check

Check electrical continuity using a digital multi-meter (DMM). Scratch the surface of the anode with the
DMM probe to make good contact if the anode is oxidized. All measurements must be less than five ohms.
If not, reinstall the affected anode.
Housing Anodes. Measure the resistance between all four anodes. Scratch the surface of the anode with
the DMM probe to make good contact if the anode is oxidized. The resistance should be less than five
ohms.
Transducer Anode. Remove the housing. Measure the resistance between the anode and any one of the
four screws holding the PC boards to the transducer. The resistance should be less than five ohms.

Zinc Anode Replacement

To remove and replace the zinc anode/s:
1. Remove the RTV from the anode screw heads. Remove the screws.
2. The anode may stick to the H-ADCP because of the RTV used during assembly. To break this
bond, first place a block of wood on the edge of the anode to protect the housing anodizing and
paint. Carefully strike the block to loosen the anode.
3. Clean the bonding area under the anode. Remove all foreign matter and corrosion. Apply a con-
tinuous 1 to 2 mm bead (0.04-0.08 in.) of RTV around each screw hole.
4. Set a new anode in place and fasten with new screws.
5. Fill the counter bore above each screw head with RTV. The RTV protects the screw heads from
water and prevents breaking the electrical continuity between the anode, screw, and housing.
Do not cover the top surface of the anode with RTV. The anode must contact seawater.
6. Check the electrical continuity. If any measurement is greater than one ohm, reinstall the affected
anode.
Do not connect other metal to the H-ADCP. Other metals may cause corrosion damage. Use
isolating bushings when mounting the H-ADCP to a metal structure.
Do not use zinc anodes with an iron content of more than 0.0015%. The major factor
controlling the electrical current output characteristics of zinc in seawater is the corrosion film
that forms on the surface of the zinc. Corrosion product films containing iron have a high
electrical resistance. As little as 0.002% iron in zinc anodes degrades the performance of the
anode.
Do not use magnesium anodes. Magnesium rapidly corrodes aluminum housings.
EAR-Controlled Technology Subject to Restrictions Contained on the Cover Page.
May 2015
Page 59