Re: XRD Shutter failure

["William A. Fendt" <35346@strauss.udel.edu>]

We had a similar problem with the old type gravity shutter mechanisms and 
required continuous GM monitors to be placed near sampler chamber cover 
which alarms if shutter failure.  Bill Fendt U of DE

On Fri, 16 Dec 1994, Rodney Ice wrote:

>         
>         I have recently experienced an X-Ray Diffraction Unit Shutter
> failure that resulted in an extremity exposure.  The shutter was a Charles
> Supper shutter, approximately ten years old.  The shutter, depending upon
> the mounting plate, can be used on a variety of X-Ray Diffraction units.
> The shutter failed to close due to lost tension of the spring around the
> solenoid piston.  In addition, the "hairline" wire that closes the audible
> alarm warning signal was displaced from its original position needed to make
> contact.
>         A survey of other XRD's on campus located one additional Charles
> Supper shutter of approximately the same age.  Evaluation of this second
> shutter indicated a loss of spring tension, however not to the degree of the
> shutter that caused the incident.  This second shutter also had the audible
> alarm "hairline" wire out of alignment but it was still making periodic
> contact. The user of the equipment had noted in the user logbook that he was
> having problems with the shutter and that it possibly needed cleaning.
>         There is a red warning "flag" or "pin" that extends out of the
> shutter mechanism that also indicates that the shutter is open.  In both
> cases, our users had molded  thin lead sheets around the shutter so that the
> pin was not visible.
>         I suggest that you check any XRD units that you have that are
> operated by aging Charles Supper shutters.  Specifically check the red
> "flag" or "pin" for smooth, easy and full tension.  There should not be any
> free play in the "flag" or "pin" of the shutter.  Any free play indicates
> only partial or no closure of the shutter.  Futhermore, check with users
> regarding the audible signal. Is the signal clear and non-varying in
> intensity?  
>         Although both symptoms (flag and audio) appear to be independent
> problems, both are indicative of aging shutters that should be replaced.    
>         
> Rodney Ice
> Nuclear Engineering, Georgia Tech
> 
>