Tip Selection
Tips must seal properly on the shaft to assure an air-tight seal and
avoid leaks or poor accuracy.
Tips must be soft and flexible so that the shaft is not scratched or
worn prematurely.
The tip orifice must be the correct size, and orifice size and
geometry must be consistent from tip to tip. Otherwise, accuracy
and precision will be affected.
Interior and exterior surfaces must be clear, smooth, and
hydrophobic to avoid retention of liquid. Too much retention results
in poor accuracy and reducibility.
Specified performance is guaranteed only when OHAUS disposable
tips are used as recommended in this manual.
OHAUS cannot accept responsibility for poor performance resulting from
the use of tips by other manufacturers. OHAUS tips are molded from
premium-grade virgin polypropylene plastic. Samples from each lot of tips
are inspected microscopically to ensure that every lot meets OHAUS's high
standards.
Tip Immersion Depth
The recommended depth for tip insertion into the sample for each ACROSS
P
model is shown in the table below:
RO
Model
2 - 10 μL
20 - 100 μL
200 - 1000 μL
5000μL – 10 ml
Tip immersion depth is important. If exceeded, the volume measured will be
inaccurate, possibly out of specification.
Tip angle is also important. Hold the pipette vertically, or within 20 degrees
of vertical.
Immersion Depth
1 – 2 mm
2 – 3 mm
3 – 6 mm
6 - 10 mm
5