GMP 6 – 2019 Page 1 of 2

This publication is available free of charge from: https://doi.org/10.6028/NIST.IR.7383 -2019

GMP 6

Good Measurement Practice

for

Cleaning Metal Volumetric Measures

1 Cleanliness requirements

All volumetric test measures, including laboratory standards and those submitted for 

calibration must be clean at the time of measurement. Drainage is altered by greasy and 

oily surfaces. Corroded surfaces raise questions that impair future use, so corrosiondamaged containers may not be worth testing. Maintaining clean volumetric test measures 

improves reproducibility of delivered volume between calibration and usage. 

Many laboratories will not accept test measures and provers for calibration unless they 

have been suitably cleaned to remove contents such as petroleum or other chemical 

residues. In those cases, all surfaces (inside and out), drain lines, pumps, and hoses that 

may be used during the calibration process must be cleaned so that no petroleum or other 

product residue remains that would otherwise spill onto the laboratory floor or drain into 

the sewer/waste-water system.

2 Cleaning methods

Metal measuring vessels are best cleaned by using a non-foaming dishwashing detergent. 

Warm water is most effective both for cleaning and rinsing, which must be thorough. If 

warm water cleaning and rinsing is used, the vessel must be equilibrated to calibration 

temperatures before use or calibration. 

The cleaning operation involves the use of a liberal amount of the detergent solution and 

vigorous shaking, swirling, or other motion so that the solution contacts the entire inner 

surface of the vessel. Depending on the condition of the surface, this operation should be 

repeated one or more times to ensure removal of oily films and residues. As much as 

possible of the detergent solution should be drained prior to the water rinses to facilitate 

complete removal of the detergent from the prover. Ordinarily, three rinses will be 

sufficient, but this should be confirmed by testing the final rinse for any visual evidence of 

detergent or other residues. 

When detergents are not sufficient to remove oily or greasy deposits, solvents may be used, 

provided it is ascertained that they do not affect any coatings on the container. The surfaces 

should be dry before any calibrations are attempted. 

If lime or scale build-up has occurred (usually only in standards that are primarily used 

with water), they may be cleaned with a suitable lime or scale remover. Many of these 

chemicals contain acids and may react with metals, so appropriate care should be taken,

and these chemicals should not be allowed to soak for extended periods of time. Many lime 

and scale removers have safety and handling requirements and may have special disposal 

requirements. 
GMP 6 – 2019 Page 2 of 2

This publication is available free of charge from: https://doi.org/10.6028/NIST.IR.7383 -2019

Safety requirements

The safety data sheet (SDS) must be reviewed prior to using or disposing of scale 

and lime removers. 

3 Drying and protection

After cleaning or use, vessels should be drained completely and stored in a dry place. They 

should be covered to prevent entrance of dust and foreign matter. Metal containers further 

should be protected from damage by denting and/or dropping. Once such a vessel has been 

visibly dented, it is difficult to ascertain whether additional changes have occurred. Even 

when dents have been removed and the vessel has been calibrated, visual deformities can 

compromise future use. Accordingly, protection from damage while stored and when in 

use should be a major concern of the metrologist or owner of the device.