Re: [foxboro] Locking / Disabling equipment

We too use the DISABLE parameter, but to only inform the rest of the
logic that this device is out of service. We still do physical lock out
/ tag out for all devices. I don't think a software lock would met the
OSHA specifications, but I'm not a safety expert.

Ken Moore
Celanese Emulsions
Enoree, SC=20

-----Original Message-----
From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx]
On Behalf Of brad.s.wilson@xxxxxxxxxxxxxx
Sent: Wednesday, August 24, 2005 2:12 PM
To: foxboro@xxxxxxxxxxxxx
Subject: [foxboro] Locking / Disabling equipment

We're wrestling with the best way to lockout equipment operated by the
DCS.
Our policy states that the technician doing the work must ultimately be
in sole control of the locking "device".  The obvious (and advertised)
method to prevent operation of a DCS-controlled device is via the block
DISABLE parameter.  However, anyone with access to SELECT (or any other
way to get block default display) also has access to the DISABLE
parameter.  Our past practice has been to physically lock a motor
starter, disconnect a valve air supply, remove a valve acruator, etc,
rather than rely on the DCS for a secure lockout.

I'd like to know how other users manage lock/tag/try for DCS-controlled
equipment.

Brad Wilson
ExxonMobil Chemical Co
Edison Synthetics Plant
732-321-6115
732-321-6177 fax
Brad.S.Wilson@xxxxxxxxxxxxxx

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