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Arthur Holland runs Holland Technical Skills, Oakville, Ontario, a consulting firm specializing in temperature and power control technology, training and technical writing. He can be reached at (905) 827-5606; fax (905) 827-5606; or e-mail aholland51@cogeco.ca.
Some
of the little boxes wired or attached to parts of your process could be signal
conditioners. They all have inputs and outputs and commonly
perform some functions not being done by the main control system.
As noted so succinctly in Wikipedia, the online encyclopedia, fail-safe or fail-secure describes a device or feature which, in the event of a failure, fails in a way that will cause no harm (or at least a minimum of harm) to other devices or create a dangerous hazard to personnel. What does fail-safe mean for you?
Some little boxes, wired or attached to parts of your process, could be signal conditioners. They all have inputs and outputs and commonly perform some functions not being done by the main control system.
In part 1 of this brief series (April 2008), I looked at the most common application for split-range controllers -- the heating and cooling of the barrel zones of plastics extruders. This month, I will continue the discussion and look at managing heat/cool processes using control valves.
The most common split-range application is the heating
and cooling of the barrel zones of plastics extruders. On
startup, the heat output of the controller takes the barrel zone up to
working temperature. Heat delivery is usually modulated (that is,
turned up or down) using the time-proportioning mode, by magnetic or
solid-state contactors.
Transparency
is vital at all levels of a heat-processing operation -- including cooperation
of personnel during specification, design, documentation, construction and
startup.
In
this brief series, I’ve described three industrial incidents that demonstrate
the potential cascading effects that failing to consider the human
factor and to ensure equipment reliability
can have. What
can we learn from incidents such as these?
In
Part 1 of this brief series, I described three industrial incidents
demonstrating the potential cascading effects that failing to consider the
human factor and ensure equipment reliability can have. What can we learn from
incidents such as these?
From
the three incidents described here, culled from inquiry reports, it is clear that both
the human factor and equipment reliability call for close examination in anticipation
of the next disaster.