Chapter 1, Basic Operation
Operation Manual
GEMINI Twin-Port Sampler
1-7
Helpful Hints
1. The needle valves have very fine threads and seats; do not
force them closed. If no sample is to be taken through one
side, simply turn the valve clockwise until resistance is felt;
then, stop.
2. Do not attempt to operate the Sampler with needle valve
settings beyond the point where the top of the slotted
portion is flush with the brass valve body.
3. There is a very small interaction between the setting of the
two flows. The flows can be most quickly and accurately set
by:
• Presetting both valves to the approximate flow desired:
• 50 ml/min. = one turn counterclockwise
• 200 ml/min. = two turns counterclockwise
• 350 ml/min. = three turns counterclockwise
• If samples are to be taken at two different flow rates,
calibrate and fine adjust the higher flow rate tube
position first.
If the total flow through both tubes is near the 500 ml/min.
limit and difficulty is experienced, try increasing the pump
setting to 1.7 LPM or use some other equipment to make sure
the pump is actually delivering 1.5 LPM when loaded to 25” w.c.
4. When operating two Samplers from one pump, these hints
are even more important. Presetting all four valves will
make calibration easier. If all four tubes are set for high
flows and the total flow is near the 500 ml/min. limit,
make sure the pump is drawing 1.5 LPM. If some
additional care is taken when calibrating and fine adjusting.
