From rcrane at snf.stanford.edu  Thu May  2 18:01:28 2002
From: rcrane at snf.stanford.edu (Dick Crane)
Date: Thu, 02 May 2002 18:01:28 -0700
Subject: DCS flow problem
Message-ID: <3CD1E168.35A048@snf.stanford.edu>

Nitride users,

At 0500 this morning and again around 1100 this morning the tylan
nitride had a DCS MFC alarm and an out of spec flow rate. Both runs were
of a long (6 hr) duration. A short (1 hr) dep was successfully run this
afternoon. No obvious faults were found at the gas cylinder/purge panel
or at the MFC. Gas pressure, cylinder and gas panel temperatures and
product volume were all normal. Maintenance will run a six hour dep
starting at 0630 tomorrow morning in an attempt to observe the failure
mode and take corrective action.

The nitride tube is not reliable at this time. If you wish to run
tonight or until we find and repair the problem, do so at your own risk.

Sorry for the inconvenience,

Dick



From rcrane at snf.stanford.edu  Wed May 29 13:38:37 2002
From: rcrane at snf.stanford.edu (Dick Crane)
Date: Wed, 29 May 2002 13:38:37 -0700
Subject: Current status DCS fault
Message-ID: <3CF53C4D.2874AB1A@snf.stanford.edu>

Nitride users: The DCS issue continues to be an annoyance. Last Sunday
the DCS MFC faulted twice during one run in the afternoon. Given the
time and temperature, DCS condensation was, most likely, not the cause.
The maintenance crew has installed a datalogger on the DCS MFC to
monitor control and response signal in hopes of catching and identifying
the fault. As a user, you need not do anything differently. If you
experience a DCS fault, please notify Ted or Ray.

In the mean time the "Yellow" light remains on as the DCS problem may
surface at anytime. Please use the nitride tube with this in mind.

Thanks for your patience,

Dick



From tberg at snf.stanford.edu  Thu May 30 08:44:50 2002
From: tberg at snf.stanford.edu (Ted Berg)
Date: Thu, 30 May 2002 08:44:50 -0700
Subject: Nitride Tube
Message-ID: <3CF648F2.89F6102B@snf.stanford.edu>

Hello Users,
    The data logger is now connected to the DCS MFC.  We successfully
monitored the run last night and the flow exactly matched the setpoint
throughout the run.  We will continue to monitor all runs to further
investigate flow issues.  any issues please contact Ray, Dick , or
myself. thanks,ted