Skip to main content

NOTICE: Due to a lapse in annual appropriations, most of this website is not being updated. Learn more.

Form submissions will still be accepted but will not receive responses at this time. Sections of this site for programs using non-appropriated funds (such as NVLAP) or those that are excepted from the shutdown (such as CHIPS and NVD) will continue to be updated.

U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Gravimetric Standard for Liquid Micro-Flow

Gravimetric Micro-flow Standard
Gravimetric Micro-flow Standard

The dynamic gravimetric standard is used to calibrate micro-flow meters and to conduct research on new flow sensors.  This micro-flow standard measures mass flows dm/dt of water from 0.16 µg/s to 16 mg/s with uncertainty of 0.1 µg/s +0.002×dm/dt [µg/s], at a 95 % confidence level. The standard has been validated by informal comparisons with the national metrology institutes of Switzerland and Denmark.  NIST’s micro-flow standard uses either an elevated reservoir or a syringe pump to generate the flow that passes through a meter under test and it is then collected in beaker resting on a (6 g full scale) micro-balance that weighs the beaker every 0.4 s.  The time-rate-of-change of the buoyancy-corrected weight gives the mass flow.  The water flows from the meter under test into a glass pipette that passes through the free surface of the collected water.  Evaporation of water from the collection beaker is retarded by covering the free surface with a low-vapor-pressure oil layer.

Created May 10, 2016, Updated August 24, 2016
Was this page helpful?