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EFD Orange (Zero draft) - This
type is recommended for the majority of automated dispensing
applications. These stoppers have straight sides and
work well auger valves (DV-06 and series) or
any other DV- series valve. The stopper does not interfere
with the syringe walls and allows material to flow smoothly.
Since there is a small clearance between the stopper
and the wall, it is important to push the follower firmly
into the fluid to make a good seal between the follower
and the syringe wall. This type of follower will leave
a residue on the syringe wall, but this amount of material
is insignificant.
EFD White (No drip) - This follower type is
designed for hand held time pressure dispensing directly
from a syringe. It works well for that application,
but is generally not recommended for automated dispensers.
The follower has an "hourglass" shape and
wipers that form a tight fit with the syringe wall.
Since the follower has mechanical interference with
the wall, it can cause inconsistent dispensing or dripping
when used with most valves or pumps. Exception: Dripping
can be prevented if this follower is used with a DV-01
valve.
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EFD Black Rubber - This follower
type is not recommended for automated dispensing. It
is designed for use with a hand operated plunger and
does not belong in automated equipment. It can cause
dripping and consistency problems like the white follower,
only worse.
Semco Yellow - While we have had success dispensing
consistently with this type of follower, it can lower
flow rates for some materials. It has very thin wipers
that wipe the syringe wall clean, but with very little
resistance.
Wax Plugs - Recommend but not readily available.
Some fluid formulators put a wax plug over the fluid.
Typically you can see this in solder paste packaging
and some pre-mixed epoxies.
Note: This information was last edited on on August
23, 2002
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