North Carolina Administrative Code › Title 19A - TRANSPORTATION › Chapter 03 - DIVISION OF MOTOR VEHICLES › Subchapter D - ENFORCEMENT SECTION › Section .0500 - GENERAL INFORMATION REGARDING SAFETY INSPECTION OF MOTOR VEHICLES › Section 03D .0552 - PHOTOMETER DESIGN AND PERFORMANCE REQUIREMENTS

Current through Register Vol. 39, No. 2, July 15, 2024
(a)
				  Multi-piece photometers shall be designed to be operated by one person on front
				  windows, roll-down and non-roll-down side windows, and rear windows with up to
				  1/4-inch glass thickness. The multi-piece photometer shall have a three-digit
				  digital readout capable of displaying from 00.0% to 99.9% transmittance with a
				  resolution to the nearest 1/10 of 1%.
(b) The multi-piece photometer shall
				  incorporate an automatic alignment feature or positive alignment indication
				  such that the alignment of the transmitter and receiver are accomplished either
				  automatically by respective devices or through an electronic noise indicating
				  proper alignment, a light indicating alignment, or a feature that prevents
				  readings being taken without the device being aligned. The automatic field of
				  view of the transmitter and receiver shall be large enough to provide an
				  accurate reading of the true net transmittance of the measured
				  window.
(c) All photometric devices
				  shall maintain unit accuracy within plus or minus three percentage points of
				  reference samples between ten and seventy percent net light
				  transmission.
(d) All photometric
				  devices shall have a repeatability of plus or minus one percentage point from
				  reading to reading.
(e) If the
				  unit's supply voltage falls below the usable operating range, the device shall
				  produce a low battery indication or fail to perform testing. Accurate readings
				  must not be affected by the unit's supply voltage. The unit's power supply
				  shall be capable of producing a minimum of 200 readings before replacement or
				  recharge.
(f) Photometric devices
				  shall fail the Division's certification if it is affected by outside stray or
				  ambient light sources. In addition to physical light barriers, such as felt
				  covers and rubber gaskets, the photometer shall include some form of electronic
				  filtration or cancellation of any stray or ambient light sources.
(g) Photometric devices shall not be affected
				  by interference generated by electric equipment, tools, or lighting devices.
				  Readings shall not fluctuate when close to operating electric motors or
				  lighting sources.
(h) Operating
				  humidity range shall be 0-100% non-condensing. Operating temperature range
				  shall be zero to 110 degrees F.
(i)
				  Photometric devices shall incorporate a means of compensating for temperature
				  and humidity changes within the stated ranges of this Rule. Acceptable units
				  shall be capable of demonstrating both accuracy and repeatability of
				  transmittance readings throughout the operating temperature and humidity ranges
				  under Paragraph (h) of this Rule.
(j) The multi-piece photometer's transmitter
				  shall have a light source capable of providing a uniform intensity beam that
				  can accommodate the alignment capabilities of the receiver. Multi-piece
				  photometers shall incorporate a means of self-alignment or positive alignment
				  indication that shall be accomplished when the source and detector units are
				  placed on their respective surfaces of the glazing to be measured as described
				  in Paragraph (a) of this Rule. The alignment shall be accurate enough to
				  position the detector unit within the uniform beam of the source. The result of
				  this alignment feature shall be data that meets the accuracy and repeatability
				  requirements of this Rule.
(k)
				  Reference samples shall be glass with a warranted transmittance stability of at
				  least one year. Reference samples shall provide a uniform surface reading at
				  four points with a variation not to exceed one percentage point as measured by
				  a calibrated spectrophotometer over an indicated range within 560nm with a
				  variance of no more than 20nm. Reference samples shall be labeled or inscribed
				  with the manufacturer's name, address, and date of calibration. Manufacturers
				  shall ensure replacement reference samples are available to the consumer within
				  two working days in the event of damage or breakage.
(l) Photometric devices shall include an all
				  segments display option for testing the unit's LCD display segments. This test
				  may be performed prior to each reading or through a separate test
				  button.
(m) Photometric units shall
				  incorporate devices that shall protect the light source and detector from
				  direct contact with environmental elements, dust, grease, and other products
				  associated with automotive repair shops. These devices shall also prevent the
				  user from touching either the light source or detector.
Authority
					 G.S.
					 20-2;
					 20-39;
					 20-127;
					 20-183.7(a);
Temporary Adoption Eff. November 1, 1995 for a period of 180 days or until the
					 permanent rule becomes effective, whichever is sooner;
Eff.
					 February 1, 1996;
Readopted Eff. October 1,
					 2021.