Fume Hood Performance Indicators

This section pertains to all buildings except Frick Chemistry building – see separate section below.

Hood Survey Sticker

Every chemical fume hood on campus is performance tested annually by EHS as indicated by a survey sticker affixed to the front of the hood. Do not use a hood that has not been tested within a year; e.g., is not labeled or the survey date exceeds one year. The sticker contains basic information about hood performance as of the survey date and should be consulted each time the hood is used.

The EHS Hood Number is a unique identifier for the particular hood. Refer to this number when communicating issues/problems about a particular hood.

survey sticker

The Inspection Sticker is aligned on the hood so the arrow indicates the proper location for the maximum safe sash position.

Static Pressure Gauge (Magnehelic)

magnehelic gauge

Most fume hoods are equipped with static pressure gauges that measure the difference in static pressure across an orifice in the duct, or between the laboratory and the fume hood exhaust duct. Most of the devices are aneroid pressure gauges, such as magnehelics, that are typically mounted on the front of the hood above the sash.

The gauge reads in units of pressure (e.g. mm Hg), rather than velocity. Changes in the magnehelic reading are not linearly proportional to changes in face velocity; therefore it should only be used as an index of hood performance.

The magnehelic gauge reading at the time of the most recent hood survey is shown on each fume hood survey sticker. A difference of 20% or more in the magnehelic reading from that shown on the sticker is an indication that the flow rate in the duct, and thus the face velocity, may have changed significantly since the last survey. If the user notices such a change, or has any other reason to suspect that the hood is not operating properly, contact EHS at 258-5294 for an evaluation of the hood. Please refer to the hood number when calling.

Color Coded and Digital Flow Indicators

Digital Flow Monitors

Some hoods are equipped with color indicating devices, or digital flow rate displays rather than or in addition to magnehelic gauges. These devices constantly measure the face velocity of the hood and point to green (for good) or red, or give the actual digital flow rate value.
 

Frick Chemistry Laboratory

Waldner hoods are measured at the upper sash stop (though this higher opening should only be used for loading and unloading). A PASS/FAIL sticker with date is affixed near the alarm lights. The magnehelic is marked to indicate proper reading.

Fisher hoods in the teaching labs are measured at the normal operating sash height stop and a PASS/FAIL sticker with date is affixed.

The number to use when referencing a hood in Frick is the Maximo number on the yellow sticker in the upper left hand corner of the hood sash.

Frick Fume Hood Labels

If hood performance is judged to be unsuitable for use with hazardous chemicals, a sticker with this information is placed on the hood instead of the survey sticker.

Hood do not use sticker

Hoods are routinely inspected at least annually. If a hood fails during a routine annual survey EHS will arrange for its repair. If it has been more than a year since the last inspection, contact EHS.

Note: Do not use a hood that has no survey sticker!

 

Staff

Joan Hutzly
Laboratory Safety Specialist
609-258-6251

Steve Elwood
Associate Director
609-258-6271