Hi Kim,
The usual solenoid valve is either energized or not energized, i.e. it's not
an open or closed switch. About the reasonable thing that could go wrong with
a typical solenoid is a broken lead, which would be indicated by infinite
resistance. From your information I would presume the solenoid's controller
circuit is not giving it current. 

The way to test it would be to isolate the solenoid valve (disconnect it at
least electrically) then goose it with either the correct voltage if you know
it, or a variable (dc) voltage starting low. It's probably 5 - 12 v.
John

-----Original Message-----
From: Stable Isotope Geochemistry [mailto:[log in to unmask]] On Behalf
Of Kim Baublys
Sent: Wednesday, January 18, 2006 7:44 PM
To: [log in to unmask]
Subject: [ISOGEOCHEM] more EA solenoid problems

Hi All,

We have a Carlo Erba NA1500 elemental analyser (attached to an Isoprime) 
and the auto sampler just stopped during an analytical run and will not 
operate even on manual.

By switching the compressed air lines over I can get the auto-sampler to 
close, and then switch lines again and get it to open, which shows that the 
auto sampler is working OK.

This led me to believe that the solenoid valve operating the auto sampler 
was faulty. I have tested all the coils and they have the same resistance 
(150ohms), so I am assuming that the solenoid valve is faulty.  Either that 
or it is not getting the command to operate.

Does this sound like a reasonable assumption?  Has anyone else had this 
problem before? Is there anyway to test the solenoid valve without running 
the furnaces up to temperature?

Any advice welcome.

thanks
kim