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1.9
Syringe Designs
The PG Dosing Unit has been designed with disposable low cost syringes in
mind to avoid cleaning and contamination issues. These disposable syringes
are equipped with a rubber plunger, which may not give exactly the same
volume for each new pump cycle. Other very accurate syringes will fit into
the PG Dosing Unit such as P/N860325, which contains five syringes with
PTFE plunger and PTFE tubing with a steel cannulus fitted to the free end.
Use of a PTFE or glass plunger is highly recommended for measurement of
wetting hysteresis (advancing/receding contact angles) where the pump
flow is reversed.
Please note the droplet should reach the surface and then it should
advance sufficiently across the surface without reaching the edge of the
image.
c) Press the REV button one or more times to reverse the pump flow. Please
note the droplet should now be receding until the liquid has disappeared
well inside the dispensing tip.
d) Press FWD again until the liquid appears at the dispensing tip and is ready
for a new pump cycle.
e) Press REV to finish the programming cycle.
1.6
Liquid purging
If the PG Dosing Unit has been left standing for a short time, some of the
droplet volume might be missing at the dispensing tip. Switch the mode
selector to position ‘F’ (Fill) and press momentarily on the FWD button until
the liquid reappears at the dispensing tip.
1.7
LED Indicator messages
Off
No power connected
Green
Ready to operate
Green Blink Pumping
Orange
No program entered for this mode
Orange Blink Programming in progress
Red
Syringe is empty
1.8
Functions
Mode
Button
Function
F(Fill)
(FWD)
Purges a small volume when pressed
momentarily
(REV)
Reduces the droplet volume
FWD
Pumps out liquid until released
REV
Backs the syringe to its end position if kept
pressed
-Abort operation by pressing FWD or REV
2, 4, 8
FWD
Pumps out a droplet of the preset size
(e.g. 4 μL)
S1,S2,S3
FWD
Pumps out a droplet of programmed size
Programming
REV+FWD
Enters programming mode
FWD*
Enters the requested volume
REV
Exits programming mode
C1,C2,C3
FWD
Performs a full pump cycle as programmed
Programming
REV+FWD
Enters programming mode
FWD*
Enters the requested advancing volume
REV*
Enters the requested receding volume
FWD*
Enters the requested ’top-up’ volume
REV
Exits programming mode
* Can be pressed repeatedly to increase the volume setting
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