CO2 system - is this normal?

> From: Jim Kostich <jkos at execpc_com>
> Date: Thu, 07 Nov 1996 10:37:05 +0600
> My Ultralife CO2 system has required frequent adjustments <snip>
> I'm assuming this isn't normal, but could use help in figuring out
> what the problem is.

As CO2 leaves the tank, it is changing from liquid to gaseous form and
gets colder in the process.  This may be cooling the valve, causing 
parts to contract and farbling the adjustment.  

More likely, the solenoid gets warm when it is on (at least, mine do).
This may be heating the valve, causing parts to expand and farbling
the adjustment.

> I sent the regulator, controller and solenoid back to Ultralife
> because of this and possibly a related problem: after a week or two,
> the system blasts CO2 like gangbusters for no apparent reason (no
> adjustments had been made recently).  They supposedly ran it for two
> weeks, but their only observations were that the regulator was set
> much too high and that I was obviously an idiot. 

Did they include instructions relating to that?  Or are *they* the

> (FWIW, they also sold
> me a new pH probe, because the original, after 8 months, would no
> longer register under 14.3.  Unfortunately, the "new" one won't read
> above -3.5, so I'll be doing without the controller for a while.)

Probes usually don't just "break" - they degrade over time.  I would
ask for a refund since it sounds like it was the controller.  Did you
pay more than $36 for the probe?  Got screwed if you did.  Pet
Warehouse has Broadley-James "Silver" pH electrodes for $36 which work
just swell with our Sandpoint controllers.

> Thanks in advance for any insights you can offer.

Insight #1: Their CO2 systems work somewhat worse than their
temperature controllers, which are mostly OK but marginal. 

Insight #2: Bummer that Sandpoint went out of business or whatever
happened to them.

Insight #3: Don't think I'll be buying much from Ultralife anymore.