RE: End-of-tank-dump comment -- or - Writing Checks for Checkvalves

[Bill Wichers <billw at waveform_net>]

>Hi Kevin,
>
>     I'll take a stab as to how the airline between your solenoid and check
>valve is getting sucked flat...
>
>     A lot of solenoids generate a considerable amount of heat when they are
>operating, or open. It would stand to reason that this would heat the CO2
>travelling through them. When the power is cut, the valve closes, and the
>CO2 ceases to be heated. As the CO2 trapped between the closed solenoid and
>the closed check valve cools, it shrinks in volume, sucking the flexible
>silicone hose flat in the process.
>
>     This is just a guess, but I can't think of how else it could be
>happening.

If this is the case, winding a spring of stiff wire (like some paperclips, 
or some maybe 22awg steel wire from a hardware store) around the tubing 
where it's going flat should help to keep it open. Round tubing deforms to 
an oval when "sucked flat", so if you prevent it from enlarging in one 
dimension you can keep it open. It's a simple trick that I've seen used on 
a lot of tubing benders for semirigid copper tubing.

I agree that it is unlikely that you would be able to build enough vacuum 
pressure with aquarium equipment to flatten even the soft silicone airline 
tubing.

         -Bill

>Best regards,
>
>Ron Barter
>Perth, Ontario
>
>----------------------
>
> > By the way - I added check valve #2 because without it the water being
> > "sucked" back down towards the cylinder also sucks water back from the
> > reactor into the bubble counter which eventually results in the bubble
> > counter becoming full with water (the water enters through the "outlet" &,
> > of course, when the CO2 flow reverses it can't get back out again).
> >
> > Does anyone else on the list know whether CO2 being absorbed into water
> > would provide enough vacuum to compress a silicone airline flat?
> >
> > Kevin
>


*****************************
Waveform Technology
UNIX Systems Administrator