Testing enclosures

The test is carried out by washing down the test enclosures in every direction by means of a standard hose nozzle of 6.3 mm inside diameter, as illustrated in Figure 11.11, held at 3 m from the enclosure with a water pressure equal lo a head of nearly 3 m of water (— 30 kN/iiF), enough to give a delivery rate of 12.5 litres/min. The duration of Ihe lest will be determined at 1 min/m" of the surface area under test, subject lo a minimum of 3 minuies. 

The test is carried out by completely immersing the test enclosure in water so that the head of water above the lowest portion of the enclosure is a minimum 1 m, while the highest portion is a minimum 150 mm. Duration of the test will be 30 minutes. 

Since detectors are by definition exposed to combustible gases they should be rated for electrically classified areas, such as Class I, Division I or 2, the specific gas groups (normally groups C and D), and temperature ratings. It should be noted the UL presently does not specifically test combustible gas detector sensor heads for use in classified areas, although they do tests enclosures for control and data acquisition circuits. Several other international standards do evaluate combustible gas detectors for use in classified areas (e.g., BS 6020). 

The test enclosure (77 by 74 by 30 cm) had two chambers separated from each other by a solid metal partition. The front chamber (45 by 74 cm) was connected to the rear chamber (32 by 74 cm) by a small opening (5 by 5 cm) to allow passage of the female vole. Males were tethered in the front chamber such that a female could interact with either male without physical interference from the opposing male. The rear chamber was a neutral chamber. Food and water were provided ad libitum to each male and in the rear chamber. A long photoperiod of 14L 10D and ambient temperature of 24 2°C was maintained throughout the experiment. Each trio of voles was monitored for 84 h. As the videotapes are reviewed, the duration of all physical contacts between a female and each stimulus male and occurrences of copulation are scored for hours 40 to 75, a time period when females are expected to have achieved estrous and to have pair-bonded. To date, we have scored data for seven females. 

The test enclosure shall have a 0.75-inch (1.9 cm) hole in front of the test subject s nose and mouth area to accommodate the nebulizer nozzle. 

No form of test enclosure or hood for the test subject shall be used. 

The test subject shall don the test enclosure. Throughout the threshold screening test, the test subject shall breathe through his/her slightly open mouth with tongue extended. The subject is instructed to report when he/she detects a sweet taste. 

In the factory the units are moved on pallets by forklift trucks. Two sides of the test enclosure comprise push-button controlled barriers which can be raised to permit truck ingress and exit. Limit switches on the barrier pedestals ensure the supply is off when either barrier is raised. There is also an internal safety barrier between the test panel and test piece which has a limit switch on its pedestal to switch off the supply when the tester raises the barrier for... 

Example If the ACGIH TLV were 20 ppm and the TWA concentration measured were 2000 ppm. the protection factor required would be 100. In fit testing the respirator during quantitative fit testing, the concentration of the air inside the booth, hood or test enclosure is divided by the material measured leaking into the facepiece or enclosure ... 

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