[Dsg-mvt] Request new manometer for Eel premix gas system + interlock

[Franck Sabatie]

Hello,

as was pointed out several times before, the current Eel premix gas
cylinder uses a manometer that goes up to 4000 psi full scale.

A full premix cylinder reads 0 on that scale: this is useless to check if
the bottle is empty or not.

It is URGENT to change this manometer so that we know when to change the
cylinder. I'm not sure what is the pressure expected on those bottles,
George probably knows.

Then a procedure has to be put in place to change the cylinder: someone (to
be defined) has to check every day the manometer and act accordingly. This
has to be discussed within the DSG.

Note that there is currently no interlock between the gas system and the
HV. If no gas flows through the system, it may eventually trip the HV. It
should not damage the system but it's still problematic. Such an interlock
will be developed this summer (maybe Wesley and Nathan can figure out how
to do that through EPICS). In the meantime, Wesley will put in place an
EPICS alert through an automated email sent to some email addresses
(dsg-mvt included) when no gas pressure / flow is detected at the entrance
of the gas system. Several people will know how to turn off the HV of the
MVT system when they receive this email and they should !

Thank you,
Franck
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