NIST provides calibration services for liquid flow meters. There are four primary calibration standards for liquid flow, two are volumetric based and two are gravimetric based. The volumetric based primary standards use a 5% propylene glycol and water mixture as the working fluid to match the properties of jet fuel and are: 1) The 0.1 L/s Liquid Flow Standard (formally called the 2 L Hydrocarbon Liquid Flow Standard) and 2) The 2.5 L/s Liquid Flow Standard (formally called 20 L Hydrocarbon Liquid Flow Standard). The gravimetric based primary standards use water as the working fluid and are called 1) The 65 kg/s Liquid Flow Standard (formally known as the Water Works) and 2) The 15 kg/s Liquid Flow Standard.
The 65 kg/s and the 15 kg/s Liquid Flow Standard consists of a reservoir, pumps, meter runs, and a weigh tank (3700 L and 600 L for the 65 kg/s and the 15 kg/s standards, respectively). The systems operate as constant flow facilities and use timed collections of water to compute the average flow through the meter being calibrated. The expanded uncertainty for the 65 kg/s facility is 0.05 % or less for flows from 0.67 kg/s to 65 kg/s, and 0.021 % for the 15 kg/s facility for flows from 0.2 kg/s to 15 kg/s (k = 2 or approximately 95 % confidence level).
Pipe connections for the 65 kg/s facility should be ASA 150 lb steel flanges, Victaulic™ couplings, or adapters thereto. Pipe connections for the 15 kg/s facility should be 2 in sanitary or adaptors thereto.
The 0.1 L/s and the 2.5 L/s Liquid Flow Standards are piston provers. Flow determination is based on the piston displacing a known volume of liquid in a measured amount of time. The expanded uncertainty for the 0.1 L/s standard is 0.03 % for flows from 0.003 L/s to 0.1 L/s and 0.06 % for the 2.5 L/s standard for flows from 0.02 L/s to 2.5 L/s (k = 2 or approximately 95 % confidence level).
Pipe connections should be A/N fittings and National Pipe Threads up to 2.54 cm (1 in) in diameter. Because meters calibrated on these standards are typically used to meter hydrocarbon liquids and may contain parts that are not compatible with water, meters are cleaned and dried following calibration on these provers. Meters are rinsed with ethanol and then dried by capping off one end of the meter and applying vacuum to the other for approximately one hour. Meters may be treated with a lubricant following drying at the customer's request.
Meters can be calibrated if the flow range and piping connections are suitable, and if the system to be tested has precision appropriate for calibration with the NIST flow measurement uncertainty.
A normal flow calibration includes five different flows, with five averages of the meter readings and the standard flow made at each set point, with this entire test sequence repeated on a second occasion to assess reproducibility. It is helpful if the customer specifies the flow set points and the instrumentation requirements of the meter (pressure, temperature, full scales required, etc.). We deliver a calibration report that includes an uncertainty analysis for the flow meter calibration factor (Note that the uncertainties in meter factor may be larger than the uncertainties of the primary standard due to extra reproducibility of the meter under test and the uncertainty of instrumentation associated with the meter under test). NIST reported uncertainties include the uncertainty of the primary flow standard as well as uncertainty attributed to reproducibility of the meter under test and the uncertainty of any customer provided instrumentation associated with measuring the flow meter output.
Calibration fees for this and other services can be found in the Calibration Fee Schedule. To read more about our facilities, see the NIST Special Publication 250-1039r1, NIST Special Publication 250-73, and NIST's Fully Dynamic Liquid Flowmeter Standard.
Turnaround time for a single flow meter is approximately 4 weeks:
- Allow 2 weeks for shipping;
- 1 week for set-up and data collection; and
- 1 week for report writing and review.
To have your flow meter calibrated on one of the 0.1 L/s standard or the 2.5 L/s standard contact Sherry Sheckels to schedule your calibration dates. To have your flow meter calibrated on the 65 kg/s standard or the 15 kg/s standard contact Joey Boyd to schedule your calibration dates.