The real challenge is making sure users understand the system in the lab they are working in, especially if they work in multiple spaces.
Our Chemistry building (50+ years old) has different hood operations depending on the lab
- Scheduled operations; off nights and weekends. Better suited for teaching labs (But do they have night labs? Does the schedule adjust for them?). Challenges include hoods that might have unattended operations (especially in labs that have been converted into research labs), weekend prep for courses, etc. In general the schedule can be overridden by calling the Central Heating Plant (CHP) but does the user understand this?
- Scheduled operations with local override. In many of the labs there is a switch that goes between "automatic" and "hand." Hand = manual which isn't necessarily intuitive to many people (I've had people tell me that they thought "automatic" was the override). In addition to understanding the settings, do the users know the schedule for "automatic?"
- Some spaces (including those outside the Chemistry building) have local ventilation that is only active when the user calls the CHP to have it turned on. This is more common for canopy hoods over ovens and equipment. We inspected a lab that had instructions on how to contact CHP on the door, but not on the ovens or hood themselves, if you missed it on the way in.
- Local control located in another room. Looked at a space with a canopy, but the switch for the motor is in another room.
- Local control in which the switch isn't clearly labeled. In biology we had an older hood with a switch that said "on"...the problem was it only turned the light on. There was a second switch (which I ended up labeling clearly) that actually activated the fan motor. We also ran into this on ventilated BSC's -- one switch for the BSC (it hums) and a second for the penthouse exhaust fan (although in that case the ventilation error alarm eventually goes off if both switches aren't activated).