Colour
Colour is an important indicator for product quality and process control
The colour acts as an important indicator of product quality and processing performance throughout the industry. Specifically in the bulk liquid shipping, colour is used as:
– A key indicator for Wall Wash Test
– A quick check on contamination of cargoes
APHA or Hazen or PtCo Colour
“APHA” stands for American Public Health Association Color Scale. APHA / Pt-Co or PCU/ Hazen colour scale is specified in ASTM D 1209 and is widely used for clear liquids such as petroleum spirits, solvents and alcohols. The Pt-Co/APHA-/Hazen colour scale uses an acid solution of potassium hexachloroplatinate (IV) and cobalt (II) chloride. The reference solutions are designated according to their platinum content in mg/l.
The scale ranges from distilled water at 0 (distilled water) to 500 (pale yellow). Intermediate Pt-Co colour standards are made by dilution of the Pt-Co stock solution as described in ASTM D1209.
The scale ranges from distilled water at 0 (distilled water) to 500 (pale yellow). Intermediate Pt-Co colour standards are made by dilution of the Pt-Co stock solution as described in ASTM D1209.
APHA/Pt-Co/Hazen is used In the chemical and plastics industries to differentiate trace amounts of yellowness in near colourless liquid samples.
ASTM Colour
ASTM Colour scale is specified in ASTM D 1500 and ASTM D 6045 and is widely used for petroleum products including lubricating oils, heating oils and diesel fuel oils with colour characteristics ranging from standard white to dark red/brownish.
Saybolt Colour
Saybolt Colour scale is specified in ASTM D 156 and ASTM D 6045 and is used for light coloured petroleum products including aviation fuels, kerosene, white mineral oils, hydrocarbon solvents and petroleum waxes.
Units: -16 (darkest) to +30 (lightest).
Units: -16 (darkest) to +30 (lightest).
Comparison with ASTM D-1500:
| Saybolt Colour | ASTM D-1500 |
| -16 | 0.571 |
| -10 | 0.422 |
| -5 | 0.347 |
| 0 | 0.27 |
| +10 | 0.167 |
| +15 | 0.105 |
| +20 | 0.056 |
| +25 | 0.03 |
| +30 | 0.015 |
Gardner Colour
Gardner Colour scale as specified in ASTM D 1544 is a single number colour scale for grading light transmitting samples with colour characteristics ranging from light yellow to brownish red. It is widely used for oils, paint and chemicals and such as resins, varnishes, lacquers, drying oils, fatty acids, lecithin, sunflower oil, linseed oil.
Units: 1 – 18
Units: 1 – 18
Other Colour Scales
Lovibond RYBN (IP 17 Method A) Petroleum products in terms of Lovibond Red.
Yellow and Blue units: 0 – 70 (Red, Yellow) 0 – 40 (Blue) 0 – 3.9 (Neutral)
IP Units (IP 17 Method B) Light coloured products such as refined undyed motor fuel, white spirit or kerosine Water White (0.25) to Standard White (4.0).
Units: 0,25 – 4,0
Yellow and Blue units: 0 – 70 (Red, Yellow) 0 – 40 (Blue) 0 – 3.9 (Neutral)
IP Units (IP 17 Method B) Light coloured products such as refined undyed motor fuel, white spirit or kerosine Water White (0.25) to Standard White (4.0).
Units: 0,25 – 4,0
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Approximate Colour Scale Equivalents
ASTM Colour D 1500 Union (N.P.A.) ASTM D 155 N.P.A. Colour Description 0 — Standard White 0,5 1 Lily White 1,0 1 ½ Cream White 1,5 1 ¾ — 2,0 2 Extra Pale 2,5 2 ½ Extra Pale Lemon 3,0 3 Lemon Pale 3,5 3 ½ Extra Orange Pale 4,0 4 Orange Pale 4,5 4 ½ — 5,0 5 Pale 5,5 5 ½ Light Red 6,0 6 — 6,5 6 ½ Dark Red 7,0 7 Claret Red 7,5 7 ½ — 8,0 8 —