Hi Paul:
> However, to release the interlock, a PAUSE or STOP button is pressed which
> allows the instrument to stop in an orderly way and then release the cover.
>
> Best as I can tell, a red pushbutton, with PAUSE or STOP legend and the ! in
> a triangle (to refer the operator back to the manual) would do the trick. I
To my knowledge, an interlock need not be classed as
an "emergency stop" device (which would require the
red color).
Interlocks are found everywhere, yet they are not
usually identified by the color red.
For the sake of discussion, consider two controls.
The first control is as you describe, and provides
the orderly stop followed by release of the cover.
This control is just a normal operation control and
can be any color.
The second control disconnects all power from the
unit (i.e., a disorderly or dirty stop) and releases
the cover. It would be labeled "emergency stop" or
equivalent. This second control would be red.
Neither or these controls would necessarily require
the use of the ! in a triangle.
In the case you describe, you simply have an interlock.
The interlock itself is the device which provides the
safety, i.e., the protection against the moving parts.
There are no further safety requirements regarding
operation of the interlock. De-actuation of the
interlock by a manual control does not mean that the
manual control is a safety device.
I would not use red. To me, you have described a
functional control, not a safety control. The
interlock is the safety control.
Best regards,
Rich
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