Laboratory Hoods Commissioning
(Laboratory Science Addition)
Kennesaw State University will adopt ANSI/ASHRAE 110 Standard for the new Laboratory Science Building Addition slated for completion in spring 2012. The ASHRAE Standard, ANSI/ASHRAE 110, Method of Testing Performance of Laboratory Fume Hoods, is the foremost protocol used when testing laboratory-type fume hood performance. The ASHRAE-110 “Method” is an elaborate, three-part test that involves face velocity testing, flow visualization, and a tracer gas test.
At the very early stages of design-review for the Lab Addition building, we discussed and agreed on the need to have tracer-gas testing (ANSI/ASHRAE 110 standard) conducted on the fume hoods, as the only objective means of verifying containment performance of the hoods.
Field testing (“AI”) under the hoods operating environment is critical because it takes into consideration installation shortcomings, room conditions and environmental factors which cannot be replicated in the factory test-cell. Most manufacturers already conduct “As Manufactured” trace-gas testing as part of their quality control procedures.
We have engaged key Facilities Division members as well on the issue to ensure that appropriate planning for commissioning testing is thoroughly integrated. EHS continues to explore innovative and best practices to aid in imploring efficiencies in all aspects of operations.
See you around campus!
Gerald C. Donaldson, REM
Toxicology and Anticipating Hazards
If you work in an area where chemicals or chemical products are used, you should learn how to anticipate hazards. You must understand the ways that a human body is affected by the chemicals or chemical products that you use.
Toxicology is study of the toxic properties of substances. Toxicity is the ability of a substance to produce an unwanted effect when the substance has reached a sufficient concentration at a certain site in the body. The hazard potential is the probability that a toxic exposure will occur.
Ingestion, absorption, inhalation and injection are four ways that a chemical can enter the body. In order to determine how much of a substance it takes to cause an unwanted response, toxicologists will determine a dose-response relationship. A known amount of the substance is administered to a group of test animals. The health effect (response) is observed. Then the data is extrapolated to a human being by taking into account the larger body mass and the similarity of the test animal’s organ system to a human being’s organ system.
At some point, the toxicologists will record a response to the dose. That initial response is called the threshold. A larger dose of the substance is administered to the test animals in order to determine at what level the substance is fatal. In large enough quantities, even harmless substances can be fatal.
A lethal dose (LD) is the amount of substance that is fatal to the test group. The does is normally introduced by ingestion or injection. A designation of LD50 means that at the administered dose, 50% of the test animals died. A lethal concentration (LC) is similar except that the substance is introduced by inhalation.
Toxicologists use the data to determine exposure limits for the substance in the workplace. The American Conference for Governmental Industrial Hygienists (ACGIH) publishes a Threshold Limit Value (TLV) for airborne contaminants. This is not a legally enforceable value and not every substance will have a TLV. The TLV is the concentration below which there should be no adverse effect on most people.
The Occupational Safety and Health Administration (OSHA) has adopted standards using the Permissible Exposure Limit (PEL). It is a legally enforceable concentration to which workers can be exposed but not every chemical will have a PEL. An action level (AL) is a concentration that requires action. For example, monitoring or personal protective equipment may be required.
The National Institute for Occupational Safety and Health (NIOSH) uses a Recommended Exposure Level (REL). It is usually employed when companies use four 10-hour shifts rather than five 8-hour shifts during a work week.
When you read the Material Safety Data Sheet (MSDS) and see a TLV, PEL or REL listed, keep in mind that the lower the number, the greater the risk to you. Another good value to notice is the Immediately Dangerous to Life and Health (IDLH) number. For example, isobutyl alcohol has a PEL-TWA of 100 ppm and IDLH of 1600 ppm while phosgene has a PEL-TWA of 0.1 ppm and IDLH of 2 ppm. While isobutyl alcohol is dangerous, phosgene is fatal at a much lower concentration.
As you work with chemicals and chemical products, remember that ventilation is a key ingredient in keeping you safe. Use lab hoods and exhaust systems. Wear gloves and safety glasses. If you need help in determining how to use a chemical or product safely, please contact Vanessa Biggers, Chemical Safety Manager, firstname.lastname@example.org or 2415.