2204 - CENTER MOUNT REFLECTORS 2200-6
2204.1 Description
This specification covers plastic center mount reflectors.
2204.2 Requirements
a. General. Provide reflectors that are plas tic reflector discs with a mounting hole in the center, and a nominal diameter of 3 inches. Provide the reflectors in 3 colors; white, amber and red. Provide amber and red reflectors that comply with the limits set by the High way Yellow and Red Color Tolerance Charts of the U. S. Department of Transportation. b. Construction and Materials.
1.Plastic Reflector Unit. Provide reflectors that consis t of 2 circular pieces of plastic, hermetically sealed together at the edges and at the center mounting hole. Provide units with an air space between the two sealed pieces and permanently sealed against dust, water and vapor.
a.Front (Lens). Provide reflectors whose front piece of plas tic consists of a clear and transparent acrylic plastic of the color shown in the Contract Documents. Provide reflectors whose outer surface of the front piece is smooth and highly polis hed, free from cracks, checks, projections or indentations. This surface may contain a mountin g hole and trademark identification. Legibly mold the manufacturer’s name and identification into the face near the edge. Form the inner surface into numerous small reflector elements to affect “cubecorner” retroreflection.
b.Back. Provide a plastic back that is either transparent or opaque, but sealed to the front to form an airtight seal in order to protect the reflector elements.
2.Housing and Mounting. Provide reflectors with a cen ter mounting hole with a grommet that uses either of two designs. A Type I grommet is formed as part of the backing and projects through the reflector and beyond the lens by about 1/32 in. The backing, including the grommet, is hermetically sealed to the lens. A Type II grommet is formed from nonferrous metal and applied after the reflector is assembled and sealed. Provide either type of grommet with an inside diameter of 0.19 – 0.24 inches, inclusive. c. Performance. Provide reflectors with the following minimu m Reflective Intensity per reflector at a divergence angle of 0.2º: TABLE 2204-1: MINIMUM REFLECTIVE INTENSITY Angle of Incidence Reflective Intensity (cd/ft-c) White Amber Red -4º 90 54 25 20º 45 27 12
2204.3 Test Methods
Center mount reflectors will be sampled by a represen tative of KDOT and submitted to the Engineer of Tests. A sample consists of 18 reflectors per each 5 000 reflectors for each color. For each additional 5000, or fraction thereof, add 4 reflectors to the sample size. Lightly wash the reflectors with a mild detergent and dry with a clean cloth before testing as follows: a. Coefficient of Luminous Intensity per Reflector. Determine the reflective intensity of center mount reflectors according to ASTM E 809. Measure each reflector individually at a divergence angle of 0.2º and incidence angles of -4º and 20º. Average readings taken at every 45º rotation. b. Heat Test. After measuring the reflective intensity per re flector, place a minimum of 9 reflectors face up in a horizontal position on the central rack of a forced draft oven maintained between 148º and 150°F for 4 hours. 2204 - CENTER MOUNT REFLECTORS 2200-7 Remove the reflectors from the oven and place them face up on a table to cool. Allow th e reflectors to return to room temperature, wipe the reflectors with a clean chamoi s and measure the reflective intensity of each reflector as described in subsection 2204.3a . The reflective intensity of each reflector must not be less than the minimum values shown in subsection 2204.2c. c. Leakage Test. After measuring the reflective intensity per reflector, immerse a minimum of 9 reflectors face down in water in a vacuum desiccator under a coarse br onze or stainless steel screen to keep them beneath the water. Cover the desiccator and slowly reduce the air pre ssure in the desiccator until a vacuum of 20 inches of mercury is obtained. Hold this reduced pressure for 5 minutes and then allow air to slowly enter the desiccator until the pressure is equal to atmospheric pressure. Allow the reflectors to remain under water for an additional 5 minutes. Remove the reflectors from the water and wipe off the excess water with a clean cloth. Measure the reflective intensity of each reflector as described in subsection 2204.3a. Any reflectors that have filled with any water will be marked as failures and the reflective intensit y will not be measured. The reflective intensity of each reflector must not be less than the minimum values shown in subsection 2204.2c. d. Resampling. When only 1 reflector per sample fails subsection 2204.3a., b. or c., the entire sample will be accepted for use on KDOT projects. A failure of 2 reflect ors per sample will require resampling and testing. A failure of 3 or more will cause the entire sample to be rejected without resampling.
2204.4 Prequalification
None required.
2204.5 Basis of Acceptance
Each lot or batch will be sampled by a representa tive of KDOT and tested as necessary to verify compliance with the specification. Satisfactory performance in the field.
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Source: Standard Specifications for State Road and Bridge Construction, 2015 Edition. Pages 910–911 of 978. View official source ↗