From: Howard Wieman (HHWieman_at_lbl.gov)
Date: Tue May 20 2003 - 08:32:06 EDT
Hi All,
It looks to me, unless someone changed it, that the regulator is basically
not regulating and that it is set to always be open, which is fine. The
pressure we see I would guess is just the vapor pressure of isobutane at
what ever temperature it happens to be. I saw one number of 31 psi at 70
deg F which is probably gauge pressure. I found a graph that shows the
pressure will increase to 37 psi gauge at 80 degF. I'm sure that any self
respecting pressure meter can be over pressured by a factor of 2, so I would
not do anything (your pressure meters max scale at ~30psi gauge). The flow
meter I understand is holding constant flow, so again no problem, but I
don't know the recommended input pressure spec for the mass flow meter. I
would recommend getting the correct regulator for your pressure range, both
for the inlet bottle pressure and regulated output pressure to avoid future
confusion. An alternative might be removing the regulator all together, but
my guess is that this would violate the safety review you probably had to go
through.
Howard
----- Original Message -----
From: "Geary Eppley" <eppley_at_physics.rice.edu>
To: <hhwieman_at_lbl.gov>; <majka_at_hepmail.physics.yale.edu>
Cc: <tofp_at_physics.rice.edu>
Sent: Monday, May 19, 2003 4:10 PM
Subject: Re: pressure on isob.
> Hi Howard and Dick,
>
> Zhangbu is not around this week but we have two knowledgeable shift
leaders
> this week who could back off the gauge pressure on the TOF isobutane
> regulator. This is not essential since I don't think the pressure can get
> high enough to damage the gauge. We try to keep the gas pressure at about
> one atmosphere out of the regulator. Dick I believe already knows where
> the TOF isobutane is. It is in the rack with the TPC test gasses, just
> toward the gas room from the TPC methane. The isobutane is a size G bottle
> with 11 lbs of product when full. If you have a spare moment, you can back
> off the regulator a few clicks. It can't be backed off very far since it
> is nearly open. It will take several hours to see the pressure drop since
> the flow rate is 3.5 ccm.
>
> If you don't want to fool with this, it should not make any difference.
>
> Cheers,
>
> Geary
>
>
> On Mon, 19 May 2003, Geary Eppley wrote:
>
> > Hi Frank,
> >
> > I won't be back at BNL until 5/22. I don't think the pressure will get
> > high enough to damage the gauge but if Zhangbu could reduce the pressure
a
> > few clicks it wouldn't hurt. This has to be done slowly and it will take
> > several hours to see any results.
> >
> > Geary
> >
> >
> > On Mon, 19 May 2003, Frank Geurts wrote:
> >
> > > Geary and/or Zhangbu,
> > > i got a phone call from SCR: apparently the pressure of the
> > > isobuthane(?) has gone up from 30 to 32psi and according to the
current
> > > shiftleader somebody told him that the pressure should not go above
> > > 30psi. The pressure history typically is somewhere between 15-20psi.
> > >
> > > Zhangbu, could you at some point (or Geary if he's back from CERN)
check
> > > the pressure on the bottles and maybe lower it a little.
> > >
> > > thanks,
> > > Frank
> > >
> > >
> > >
> >
> >
>
>
>
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