Air Testing     Common Methods Odor panel Scientific evaluations or tests     Odor Panel   Some states have established subjective odor panel evaluations for determining odor capture.  This is an effort to make the results more objective. The panelists are trained to detect differing levels of odorous compounds.   One advantage to using the odor panel is that the nose is capable of smelling very low concentra- tions of emissions.   Some disadvantages are: The nose can become desensitized by oxidizers and other compounds in rendering air streams such as hydrogen sulfide. Panelists can be risking their health if oxidizers or other compounds such as hydrogen sulfide are in the air stream. The nose can become "fatigued" and lose the ability to smell accurately. Though the panelists are trained, it can be difficult to make objective comparisons.   Caution     Use caution when smelling the sniff tube, or air, that has come from the stack when treating with any type of oxidizer.  More information is available under OSHA Guidelines. Or see a summary here of exposure limits of oxidizers as of December 2006. Gastec type tubes are available for safely testing for these compounds in the air to insure personnel are not exceeding the OSHA safety limit.                                                                                             Plant Odor Survey   Equipment Survey   Air Testing   Odor Dispersion Modeling        Scientific Evaluation   Objective methods include gas chromatograph and Gastec type testing tubes.        Gas Chromatograph           The advantage to gas chromatograph testing is that the results are very accurate for the air sample being tested.  It is the gold standard for testing.   Some disadvantages are: The cost is relatively high. Different testing columns must be specified for the different possible compounds in rendering, each a seperate test and expense. Testing generally requires a sample to be taken by a consultant and shipped to the lab. Test results are not immediate.  They may take weeks to get back.     Gastec Tubes   Advantages to Gastec type tubes are: They are relatively accurate, up to 95%. They are relatively inexpensive. Tests can be conducted when needed. Results are immediate. The major disadvantage is that individual compounds may not be able to be differentiated from their family of compounds.  Example: the results for primary amines will not give you which specific amines.  Also there can be some interference between two different compounds.  However, if the results show no emissions, there is no interference.   A caution when using to measure odor while oxidizers are present in the air stream.  The tube results must be read as they are pulled.  The oxidizer will bleach the indicator within seconds.   Hydro Solutions relies primarily on the use of the Gastec method for testing odor in air streams, due to the high rate of accuracy, cost effectiveness, and the ability to make accurate comparisons of performance. This allows the Hydro rep or operators to make on-site, immediate system corrections.