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Syringes are widely used. Within the medical field,
predictably, and elsewhere. This is because they're dirt
cheap positive displacement pumps available in all sorts
convenient sizes, with nice connectors and valves
to fit. Sometimes, it's useful to apply pressure, or
to a syringe. Pull a slight vacuum to encourage blood to
the barrel, or apply positive pressure to a gas-liquid mix
the barrel to force the liquid through a filter, for
This can get tiring on the hands.
So, let's improve it. On the plunger, specifically on the +
section part between the thumb pad and the rubber seal,
there should be a toothed section. Possibly cut into one,
all four of the ends of the = cross section. Next, there
should be two simple, plastic flexible ratchet teeth
mounted on the barrel component. One should allow free
movement in but not out, and the other out but not in.
plunger teeth and the ratchet component should be
engaged or disengaged by simply rotating the plunger
within the barrel. Hope that's clear.
Syringe gun ratchet action
Unidirectional only, however. Your idea is better bs. [bhumphrys, Apr 22 2015]
||//Sometimes, it's useful to apply pressure, or
selective to a syringe.// I was following up to that
||Apart from that - yes, sort of. But only useful (as you
note) when the barrel contains some gas.
||fixed. This idea was inspired by the Qiagen Maxi kit.
Designed by torturers or incompetents, can't decide.
||//But only useful (as you note) when the barrel contains
||Not with the vacuum. There's plenty of times when you
might want to pull a vacuum and then open a tap
somewhere else. Vacutainers are essentially an expensive
||(Only ever used Qiagen mini and midis; the midi is a
waste of time as it's far quicker to do 10 minis.)
||On reflection, [+] because it should be possible to do
this just by slightly altering the existing plastic
||The plunger rotation (to engage either the "forward"
or "reverse" ratchet) should require a definite
positive action, with the syringe initially being in a
"no ratchet" position. I can imagine, if not, that the
feature could be annoying to people using syringes
||*As far as I can ascertain, this is the first appearance
on the interweb of the word "ratchetlessly". You
heard it here first.