API Hydrometer. Range 39-51 on API degree scale. Used as the standard for petroleum products in the United States and in monitoring oil and gas leases. Combined with thermometer in body. Scale has 0.1 divisions. ASTM# 55H. 380mm (15") length. Temperature standard: 60°F (15.56°C).
MFG# A-916L (BW#6755HTS).
Forensics Lab Supply Number 5530076.
This hydrometer has been calibrated in accordance with the A.S.T.M. standard E 126 and N.I.S.T. circular No. 555. The instrument is traceable to N.I.S.T. having been calibrated against an instrument which has been certified by the National Institute of Standards and Technology.
This instrument is an A.S.T.M. and it has been manufactured to meet the A.S.T.M. standard E 100.