May
2015
WorkHorse H-ADCP Operation Manual
Page 54
EAR-Controlled Technology Subject to Restrictions Contained on the Cover Page.
7. Tighten the bolts in small increments in a “cross” pattern until the split washer flattens out, and
then tighten each bolt ¼ turn more to compress the face seal O-ring evenly. Tighten the bolts to
the recommended torque value of 5.6 Newton-meters (50 pound-inches).
Apply equal pressure to the O-ring as you tighten the bolts. If one bolt is tightened more than
the others, the O-ring can become pinched or torn. A damaged O-ring will cause the system to
flood.
Do not over tighten the bolts that hold the transducer, housing, and end cap together. If you
tighten too far, you can crack or break the plastic housing. On the other hand, leaving the bolts
too loose can cause the system to flood. Tighten the hardware to the recommended torque
value.
The recommended torque value for the end-cap 6-mm bolts is 5.6 Newton-meters (50 pound-
inches).
Periodic Maintenance Items
Replacing the Desiccant Bags
Desiccant bags are used to dehumidify the housing interior. The factory-supplied desiccant lasts a year at
specified H-ADCP deployment depths and temperatures. Remember that desiccant rapidly absorbs mois-
ture from normal room air.
The average dry weight of a new desiccant bag is 7.2 grams ((5%). The weight increases to 8.4 to 9 grams
for a “used” desiccant bag. Used desiccant bags may be dried at 250° for 14 hours. As a minimum, replace
the desiccant bags (Table 2, item 6) whenever you are preparing to deploy or store the H-ADCP for an ex-
tended time.
Do not open the desiccant bag. Contact with the silica gel can cause nose, throat, and skin
irritation.
Do not puncture or tear the desiccant bag. Do not use desiccant bags that are torn or open.
Desiccant bags are shipped in an airtight aluminum bag to ensure maximum effectiveness.
There is a moisture indicator inside the bag. If the moisture indicator is pink, do not use the
desiccant bag until it has been dried. TRDI recommends replacing the desiccant bag when the
O-rings are replaced. All O-rings should be replaced every one to two years maximum.
To replace the desiccant:
1. Remove the transducer head (see
).
2. Remove the new desiccant bags from the airtight aluminum bag.
3. Remove the old desiccant bags and install two new ones. For Monitor and Mariner systems, place
the desiccant bags (Table 2, item 6) between the PIO board and the end-cap. For Sentinel systems,
place the desiccant under one of the rubber bands on the battery pack (see
).
4. Install the transducer head (see
).