vacuum pump is converted
1.Vacuum pumps made this way are in use around the world, in non-industrialized
areas, for vacuum packing food.
2. A manual Vacuum pump can used to make a "vacuum press" to clamp laminates together with a
ton or more of force while the glue sets. It can
also be used for vacuum bagging composites like fiberglass, to squeeze out
excess resin and make stronger, lighter parts.
3.You can use it with a
vacuum former, to form thicker plastic sheets than you could with just a vacuum
cleaner.
4. You can implode various things with it, or attach it to a vacuum
chamber and expand or explode things in the chamber; that's often fun and/or
instructive.
A plain bike pump is just a piston pump rather like a syringe, with a rubbery
disk sliding in a cylinder. Drawing back the disk sucks air into the cylinder,
and pushing it in pushes air out.
To make this syringe-like thing work as
a pump, sucking from one place and blowing to another, two "Check Valves"
(one-way valves) are used. One lets it suck in from an air intake, but not blow
out the intake. The other lets it blow out the exhaust, but not suck in from the
exhaust.
Unlike most piston pumps, a bike pump uses the rubbery disk both
as a piston and as one of the check valves. When you pull back on the pump, the
disk flexes inward and allows air around it, into the cylinder ahead of the
piston. When you push inward, the disk is stopped from flexing the other way by
a metal disk; its edge seals against the inside of the
cylinder, so that when you push it down, it compresses the air in the cylinder
and forces it out the exhaust.
To
convert the pump, we'll need to do two things:
(1) Reverse the piston
disk and the metal disk that backs it up, so that it seals on the upstroke and flexes on the downstroke.
(2) "Reverse" the exhaust check valve, so that it lets air in
but not back out, and we can use the old exhaust connection as the new air
intake. Actually, it's usually easier just to remove the check valve, and
replace it with one that does the right thing, so that's what we'll
do.
To make it easy to do both of these things, we'll want a simple,
cheap, old-fashioned bike pump with no frills to
complicate things.
More products of pumps
2012-05-31
