ISO 7686:2005 pdf download.Plastics pipes and fittings -Determination of opacity.
4.2 Adjustable-power arc or Incandescent lamp, the intensity of light of which is constant to ± I %. A filter or other means shall be provided to lemit the spectrum of the light to a wavelength of 540 nm to 560 niti. unless the refernng standard specdles otherwise.
4.3 DIaphragm and optical lenses, adjusted to obtain a parallel-sided and symmetrical incident beam whose width is adjusted according to the size of the test piece, ensuring that all light is directed onto it, and small enough to enable all light passing through to be detected by the apparatus used,
A rectangular patch of light shone on the axis of the test piece is peferred. It is recommended that the width of the light beam should not extend across more than 0,25 to 0,3 times the outside diameter of the test piece to prevent light leakage around the side of the test piece. The maxrium dimension of the light beani should not be more than 0,5 to 0,7 times the diameter of the instrument entrance port.
4.4 Support. arranged so that It maintains the surface of the test piece to be examined perpendpcular to the optical axis
5 Test pieces
The thinnest wall product in a manufacturer’s range shall be tested. Take a suitable length of the pipe, or the fining to be tested. Cut into four strips. equally spaced around the circumference.
If it is difficult to meet the recommendation given for the width of the light beam when used for measurement of small diameter pipe, the test piece may be flattened, provided no significant change m thickness ocours (see the second paragraph of 4.3).
6 Procedure
6.1 Setting up the equipment Check
a) the alignment of the installation,
b) that the reading given by the photoelectric cell is zero in the absence of light, ensuring that the photoelectric cell is protected from incident daylight,
C) that the reading Is 100% In the light emitted by the luminous source In the absence of the test piece.
4.3 DIaphragm and optical lenses, adjusted to obtain a parallel-sided and symmetrical incident beam whose width is adjusted according to the size of the test piece, ensuring that all light is directed onto it, and small enough to enable all light passing through to be detected by the apparatus used,
A rectangular patch of light shone on the axis of the test piece is peferred. It is recommended that the width of the light beam should not extend across more than 0,25 to 0,3 times the outside diameter of the test piece to prevent light leakage around the side of the test piece. The maxrium dimension of the light beani should not be more than 0,5 to 0,7 times the diameter of the instrument entrance port.
4.4 Support. arranged so that It maintains the surface of the test piece to be examined perpendpcular to the optical axis
5 Test pieces
The thinnest wall product in a manufacturer’s range shall be tested. Take a suitable length of the pipe, or the fining to be tested. Cut into four strips. equally spaced around the circumference.
If it is difficult to meet the recommendation given for the width of the light beam when used for measurement of small diameter pipe, the test piece may be flattened, provided no significant change m thickness ocours (see the second paragraph of 4.3).
6 Procedure
6.1 Setting up the equipment Check
a) the alignment of the installation,
b) that the reading given by the photoelectric cell is zero in the absence of light, ensuring that the photoelectric cell is protected from incident daylight,
C) that the reading Is 100% In the light emitted by the luminous source In the absence of the test piece.
