On Thu, May 16, 2013 at 12:50 PM, Ralph B. Stuart <rstuart**At_Symbol_Here**cornell.edu> wrote:

> Do the combination sash with lockable panels help with the misuse by student ?

I have observed combination sashes in use in a variety of labs on a variety of campuses and would say no. They are almost always operated with the process occurring behind the open part of the horizontal sash, so that there is no sash between the process and operator. The additional complicating factor is that many alarm systems track the open face area, resulting in alarms that seem to occur randomly as the sashes are adjusted, resulting in people being reluctant to move the sashes horizontally.

- Ralph

Ralph Stuart CIH

Chemical Hygiene Officer

Department of Environmental Health and Safety

Cornell University

rstuart**At_Symbol_Here**cornell.edu