ASTM E2995-15a (2020) pdf free.Standard Specification for ASTM Thermohydrometers with Integral Low-HazardThermometers.
Calibration or verification,when required,shall beperformed at three test points (approximately low, medium andhigh) on the hydrometer scale. For example, a thermohydrom-eter with a range of 9 to 21 API shall be calibrated or verifiedat approximately 10, 15 and 20 degrees API; a thermohydrom-eter with a density range of 700 to 750 kg/m3shall becalibrated or verified at approximately 700,725, and 750, andso forth. Calibration or verification shall be performed inaccordance with Test Method E126.
Calibration or verification of the thermometer scale,when required, shall be performed at two or more test points onthe thermometer scale.Test points shall be chosen to bracketthe range of use.Calibration or verification shall be performedin accordance with Test Method E77.The thermohydrometer shall be supplied in suitablepackaging that will permit the viewer to visually determine thepackage contents，identified by ASTM number，range,andadditional description as appropriate.
Manufacturers shall perform the following inspectionsbefore releasing finished instruments. For quality assurancepurposes a statistically robust percentage of each lot ofinstruments shall be inspected. If a Certificate of Conformance,however named, is issued for each instrument, the certificateshall state the quality assurance procedure the manufactureruses to issue the certificate. Inspect the hydrometer carefully to be certain thereare no cracks， fissures，deep scratches,rough areas，or otherobvious damage to the glass. Reject the hydrometer if any ofthese defects are present.
Inspect the hydrometer carefully for loose pieces ofballast or other foreign material within the instrument. Ifpresent, reject the instrument.Inspect the paper scale within the hydrometer stem.The paper scale shall be straight and without twist.
Inspect for the presence of a scale slippage indicator.If a permitted scale slippage indicator is damaged, incorrectlypositioned, or not present, reject the instrument.Check the linear dimensions and diameters for com-pliance with the Table 1 requirements by comparing thehydrometer using graduated metal rulers of the conventionaltype,or with metal templates with lines ruled at suitabledistances from reference points corresponding to the maximumand minimum values defined in Table 1.A micrometer may beused for checking diameters.Inspect the hydrometer for correctness of graduationspacing. API hydrometers are graduated with equal spacingbetween scale graduations.ASTM E2995 pdf download.