Cleaning The Pressure Sensor Port; Preventing Biofouling - Teledyne WORKHORSE Operation Manual

WorkHorse H-ADCP Operation Manual

Cleaning the Pressure Sensor Port

In order to read the water pressure, water must be able to flow through the copper screw on the pressure
sensor. The tiny hole in the copper screw may at times be blocked.
The pressure sensor is optional. It may not be included on your system.
To clean the pressure sensor port:
1. Place the H-ADCP on its' end-cap. Use a soft pad to protect the H-ADCP.
2. Use a straight-slot screwdriver to remove the copper pressure sensor port screw.
3. Gently clean out the hole in the copper screw with a needle. If the hole becomes enlarged or the
screw is corroded, replace the screw. A replacement copper screw is included in the spare parts kit
(part number 817-1067-00).
4. Install the copper screw. Tighten the screw "finger tight" (2 in/lbs). Do not over tighten the screw
or you may strip the threads on the plastic cover disc. If this happens, return the H-ADCP to TRDI
for repair.
The pressure sensor is installed in an anodized aluminum cavity that includes a plastic
protective cover to hold the copper screw. This cover is held into place with two M3 screws. The
holes where the M3 screws are inserted in the pressure sensor housing are anodized aluminum.
TRDI knows from our experience that it is difficult to anodize sharp edges on threaded holes
such as these. In marine and fresh water environments, poor anodizing on aluminum will lead
to corrosion problems. Always inspect for corrosion in this (and all) areas between
deployments.
The pressure sensor is filled with silicone oil. Never poke a needle or other object through the
copper screw while the screw is installed over the pressure sensor. You will perforate the
sensor, causing it to fail.
Do not attempt to clean the surface of the pressure sensor. The diaphragm is very thin and easy
to damage.
If the pressure sensor surface looks corroded or is bowed outward, then contact TRDI for
servicing. Do not attempt to remove the pressure sensor. It is not replaceable in the field.

Preventing Biofouling

This section explains how to prevent the buildup of organic sea life (biofouling) on the transducer faces.
Objects deployed within about 100 meters (≈328 feet) of the surface are subject to biofouling, especially in
warm water. This means H-ADCP systems are subject to biofouling. Soft-bodied organisms usually cause
no problems, but barnacles can cut through the urethane transducer face causing failure to the transducer
and leakage into the H-ADCP. Therefore, you should take steps to prevent biofouling during shallow water
deployments.
Some organizations may decide to use antifouling grease. However, most antifouling greases are toxic and
may cause problems. Recent tests suggest antifouling grease may cause the urethane on the transducer
faces to develop cracks. Warmer temperatures accelerate this effect. If using antifouling grease, remove
the grease immediately after recovering the H-ADCP from its deployment. Remove the grease with soapy
water because cleaning solvents may also cause the urethane to crack. Be sure to wear protective gloves
and a face shield.
The best-known way to control biofouling is cleaning the H-ADCP transducer faces often. However, in
many cases this is not possible.
EAR-Controlled Technology Subject to Restrictions Contained on the Cover Page.
May 2015
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