In addition to keeping fume hood sashes at the correct position, UNL Control Systems has implemented a few other measures to allow lab occupants to use the ventilation system properly in their lab as well as conserve energy when possible. It is important that auditors understand what each of these items is and understand their basic use when citing ventilation deficiencies.
Exhibit A shows a fume hood Pressure Gauge like the ones that have been recently mounted on the two older fume hoods in the EHS building. This is not a control device but it does alert the user (and auditor) to whether the fume hood is operating properly. These devices cannot be fine-tuned to be accurate indicators of airflow and as such should be viewed as either “on” (anything above zero) or “off” (zero reading). If gauge reads zero then cite this as VEN02 and inform lab occupants that the hood is not working properly. Let the Senior Specialist know immediately upon return to the office so BSM can be notified.
Attached is the information in the Appendix A handouts from your training notebook The attached PDF/your handout shows the instructional decals that should be visible in each lab where these controls are used. They may be missing in some labs but BSM is working to get them installed as needed. The “Lab Ventilation Control Notice” refers to the Occupancy Control Switch (Exhibit B) and the Fume Hood Controller (Exhibit C).
The Fume Hood Controller is the white box shown in the lower portion of Exhibit C. It is a device that will allow the user to view an approximation of the face velocity in the display screen as a percentage of airflow through the exhaust duct of the hood. Since the hoods are normalized to 100fpm airflow during certification, the readout on the display is “close” to the actual face velocity of the fume hood when it was certified last. The user may also control the exhaust rates by putting the fume hood into Standby mode (black button) when it is not in use or by pressing the Emergency button (red).
When the emergency button is activated, the amount of air being exhausted is maximized. This button is intended for situations where there is a chemical spill outside or inside the fume hood. The fume hood should not be operated in the emergency mode under normal use conditions. The increased ventilation rate could compromise the capture efficiency of the hood. Such use should be cited using VEN02. The Mute (gray) button allows the user to silence the audible flow rate alarm. It should be used on a temporary basis until BSM is able to service the hood not as a permanent measure. If the Mute button is being used, ask the occupant why.
It should be noted that the fume hood controller in this photo was malfunctioning at the time of the photo (Exhibit C) as the green Flow light is on indicating that the hood was running but the display screen reads "Zero." In a situation such as this, cite this as VEN02, inform lab occupants that the hood is not working properly and they should not use the fume hood until it is repaired. Let the Senior Specialist know immediately upon return so BSM can be notified. Occupants should never conduct operations in the fume hood if it is in Standby mode. This would result in citing VEN 02.
Exhibit B shows the Lab Occupancy Sensor which is found on the wall by a door in most labs on campus. It does not control a specific piece of equipment in the room but allows the occupant to control the amount of general exhaust room air changes at will. When occupants are working in the laboratory or active processes are occurring in the laboratory that could result in fugitive emissions, they should push the Start button and the green light will stay on. This will activate the HVAC controls to ensure that the laboratory is receiving at least six air changes per hour. During unoccupied times when active processes are not occurring, they should use the Stop button to conserve energy. Not using the Stop button when the lab is unoccupied is not a citable action but not having the system on when the lab is in use should be cited using LAB07 as the minimal ventilation exhaust rates for the room are not being used.