Campbell Scientific CVS4200 / BVS4300 Stationary Samplers - Manual (Page 38)

CVS4200 / BVS4300 Stationary Samplers
Hold the bottom nut while loosening / tightening the top
nut, or it may become loosened from the metering
chamber cover and create an imperceptible leak in the
vacuum system. CAUTION
7.4.2 Liquid Sensing Rod
This probe, also called the “level control rod”, is used to stop the sample
intake. Always ensure that its lower end is located above the volume control
tube. Approximately 1” difference is sufficient. If the fluid intake is turbulent
within the metering chamber, more than 1” may be required to ensure
splashing of fluid does not trigger probe.
In applications with substantial oil or grease, the rods can become coated and
lose their conductivity. This is prevented by cleaning the rods regularly. In
extreme cases, extra SS wire can be wrapped around the liquid sensing rod to
increase its surface area.
The liquid sensing rod and volume control tubes must be
kept clean to ensure conductivity necessary to detect the
presence of the fluid. CAUTION
Most CVS/BVS Samplers incorporate a Barrier Valve in the metering
chamber cover, where the tubing from the pump enters. It consists of a cage
containing a ball that will float if the sample should rise to the top of the
chamber without detection. Should rod conductivity fail, the fluid brings the
float into contact with an O-ring surrounding the pressure / vacuum port,
sealing the entry to the tubing and the pump (where the fluid may cause serious
damage). This O-ring Barrier Valve should be inspected regularly and
replaced as necessary.
Due to the restriction of Wetted Materials (such as, stainless steel, glass and
fluorocarbons, etc.), some models of the sampler do not contain this barrier
valve. In these units, a secondary liquid-sensing circuit may be added as a
precaution. This circuit is connected to the pump tubing fitting on the
Metering Chamber cover.
7.5 Battery
7.5.1 Charging 12 Vdc Battery and Reverse Polarity Protection
The sampler will charge only the factory installed internal battery. This
charging takes place continually as long as there is incoming line power.
Should the need arise to only charge the internal battery, as would be required
to store the sampler for an extended period of time, simply place the “RUN /
OFF” toggle switch in the OFF position, and leave the sampler power breaker
on. Twenty-four (24) hours should be sufficient to fully charge the battery.
The sampler is equipped with REVERSE POLARITY PROTECTION for
checking the connection of an external battery. When attaching an external
battery, be sure to check the reverse polarity indicator. If it is ON, reverse the
connections at the battery.
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