Ballast Water Sampling and Sample Analysis for Compliance Control - Global Maritime Transport and Ballast Water Management: Issues and Solutions - page 193

Fig. 4 Wash bottle used to
drain all organisms caught in
the cod-end
Plankton Net for In-Tank Sampling
For in-tank sampling events via an opened manhole a short plankton net with a
cone-shaped opening and with a small diameter is benefi cial as it can easily be low-
ered through a manhole. Studies have shown that the conical net top increases the
sampling performance. At the same time this net design reduces the risk that the net
becomes stuck inside the ballast water tank. A removable cod-end helps to clean the
net between sampling events of different tanks so that an “organism contamination”
from sample to sample can be avoided. An example is given as Fig. 5 .
The sampled water volume can be calculated by considering the net opening
dimension and the distance of the vertical net haul. It is recommended to use a metered
rope when lowering the net that the depth from which the net is pulled up is known.
Flow Meter
During in-line sampling events a calibrated fl ow meter should be used to enable an
accurate measurement of the water volume fi ltered through the plankton net. It is
further recommended that the fl ow meter should also show the sampling fl ow rate,
which is important for appropriate sampling planning and setup. Two fl ow meter
examples are shown in Fig. 6 .