Campbell Scientific SR50A Distance Sensor - Manual (Page 25)

SR50A Sonic Ranging Sensor
FIGURE 6. SR50A - Mounted using a NU-RAIL Fitting and
19484 Mounting Stem
SR50A with 6-plate gill radiation shield – the picture below shows the
SR50A stem attachment
5. Maintenance
The SR50A’s electrostatic transducer requires equal pressure on both sides.
Vent holes in the transducer housing are used to equalize pressure. Desiccant
is placed inside the transducer housing to prevent the possibility of condensing
humidity. The desiccant must be inspected and, if required, replaced on a
regular basis. The desiccant supplied with the SR50A uses an indicating silica
gel and will remain blue if it is still capable of absorbing moisture. Once the
desiccant becomes saturated the color will change from blue to pink. If the
SR50A is used in humid environments, the desiccant should be replaced more
frequently. To inspect or replace the desiccant, follow the procedures outlined
in Section 6 under disassembly.
The five small desiccant packets used in the transducer housing are part
number 4091.
19