"Any sufficiently advanced technology is indistinguishable from magic."
When a motor spins and fan blades turn, you've got a solid system. Add a lot of complex things and you've added a slew of failure points.
Generally speaking, simple systems are more robust.
Harry
Sent from my mobile device.
To elaborate on this a little, Ralph hit it right on the head. When we installed the systems, we had people trained. 10 years later, I'm the only person on our University that was here when these systems were installed (and I was not one of the trained ones), so we have nobody who can maintain them in house.
All of our hoods have electronic flow systems on them, with monitors that tell you flow. We had a guy come do inspections a few months back, and we have one hood that reads 100cfm on the electronic meter (as always), but in fact was only flowing 20. That was odd to me, and something totally unexpected (for that to happen, 2 fails have to be there, a flow fail and a meter fail, I think). I think people are coming to fix this soon (as we had other fails as well), but again, it requires calling in outside vendors as they are the ones who know how to fix it.
Another fail of note: ERU's require exit air and entrance air to pass past one another, with a wall between them so that air does not mix (obviously), made of material that allows for heat transfer to occur. There is usually some sort of gerbil wheel that is causing air to flow in both cases. This gerbil wheel has rubber flaps that keep exit air and entrance air from mixing. One time this gerbil wheel blew a bearing, causing it to buckle, and thus entrance air and exit air were mixing. Thankfully we were doing a smelly experiment, as it caused the whole floor to smell, so we were able to find the issue. Our University could not afford to fix the issue, so we have just shut that wheel off (and sealed it back up). It still works, and we get the air flow we need - it's just not as efficient. But again, Universities cannot maintain their building infrastructure 5-10 years past building completion.
Keep it simple
Dave
> On Oct 25, 2016, at 9:35 AM, Stuart, Ralph <Ralph.Stuart**At_Symbol_Here**KEENE.EDU> wrote:
>
>>> If possible, I'd keep it simple. I feel that=E2=80™s the best way in the long run. We installed these complex hood systems (to go with a nice ERU system) - but unfortunately they do require maintenance, and our University is not willing to call in a guy when a hood goes out (they want us to accumulate these things to make the call more worthwhile).
>
> This is an ongoing concern that I have with both emergency equipment (eyewashes and safety showers) and lab ventilation system. The trend of "standards creep" which adds more and more specifications and alarms to basic lab equipment such as fume hoods has made them significantly harder to use and more confusing to the people they are supposed to serve. I routinely see situations where fume hood "features" and other ventilation innovations have been disabled by lab occupants to avoid alarm distractions, sudden temperature changes, or inconvenience as they work. And often what the lab occupants are trying to address go beyond distractions or inconvenience to new hazards imposed by designers unaware of how laboratory work flows occur in real life.
>
> In my opinison, given the staff turnover associated with many (all academic) laboratories, maintaining a "trained" workforce for each piece of equipment they may (or may not) need to use in their laboratory career is not a reasonable design approach.
>
> - Ralph
>
>
> Ralph Stuart, CIH, CCHO
> Chemical Hygiene Officer
> Keene State College
>
> ralph.stuart**At_Symbol_Here**keene.edu
>
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