ASTM 26H Biodiesel Hydrometer API Scale 25 to 31
API (American Petroleum Institute) ASTM 26H, hydrometer with an API range of 25 to 31 @ 60 F
The API scale was designed so that API gravity increases inversely to density. Therefore, more refined products have higher API gravities.
Depending on the type of feed-stock used the API of bio-diesel will range from 33 to 25 with a specific gravity range of 0.86 to 0.90. An average API of 28.4 or s.g. of 0.885 has been reported for soy methyl esters @ 60 ∞ F
S.G.= 141.5 / (API + 131.5)
A certificate of calibration accompanies the hydrometer. Bellwether Hydrometers are manufactured in strict accordance to specifications of ASTM (American Society for Testing and Materials) for accuracy and design.This instrument is suitable for certification as a primary reference standard with NIST traceability. It meets or exceeds the tolerances of accuracy and physical specifications set forth by the National Institute of Standards and Technology. Formerly the "National Bureau of Weights and Measures".