Pressure & Flow

Pressure is one of the derived values from mass, length and time. NMC's primary pressure standard is directly traceable to these SI units and disseminate the pressure value to industry. Hence, ensuring the measurements at each industrial application to be accurate, such as air data set used to measure the altitude level of airplane, is critical for the flight safety.

Flow measurement is important to determine the amount of fluid quantities such as water, oil, gas and chemicals to be purchased and sold. Accurate flow measurements are often required, since flow measurements always involve huge amount of quantities that a measurement error of just 0.1% can make a difference of millions dollars. In addition, flow meters for fluid flow measurement have various applications that also affect measurement results including allocation metering, check metering, measurement of process, district heating, and fluid types. Each measurement has their unique conditions and fluid properties that need to be calculated carefully with expertise and sufficient experiences.

NMC has built the facilities for gas, liquid, air speed flow measurements and has proactively helped industry to solve industrial measurements issues through measurement and calibration services, consultancy and training as well as study for site measurement issues, developing measurement solutions in the area of fluid flow measurements.

The Pressure & Flow Laboratory at NMC develops, maintains and disseminates the pressure, vacuum and fluid flow metrology related national measurement standards in Singapore.

Pressure Standards

The pressure unit is realised based on physical definitions. The pressure value can be calculated from the loading weights over a piston which is so called as deadweight pressure standard or from the mercury density, local gravity and the height displacement distance in a U-tube which is so called as mercury manometer.

NMC standards are classified as:
Low pressure: 1 -13,000Pa
Medium pressure:0.01MPa to 7Mpa
High Pressure: 7MPa-400Pa

Pressure Standards  

Deadweight pressure standard

Mercury manometer

Pressure gauges

Pressure indicators

Pressure reference standards

Vacuum Standards

The realisation of the vacuum standard is based on the principle of dynamic pressure expansion. Vacuum levels can be calculated from the measurement of the pressure ratio across an orifice nozzle and the admitted flow rate.

Vacuum gauges can be calibrated in the range of 10-7 to 10-2 with measurement uncertainty of 1 - 1.3% of readings.

The standard is capable of calibrating high and ultra-high vacuum gauges such as penning gauge, hot cathode ionization gauge etc.

Vacuum Standards  

Primary high vacuum standard

Vacuum gauges used for measurement of high vacuum systems

Vacuum gauges

Reference vacuum standards

Micro- to Nano-Fluid Flow Standards

The realisation of leak standard is based on ideal gas flow. The flow rate in mole mass (N) is calculated from pressure (P), temperature (T) and volume (V) by the application of gas law N = (P*V)/(R*T), where R is the gas constant value.

Leak flow rate can be calibrated in the range of 1 x 10-12 mol/s to 1x10-6 mol/s with measurement uncertainty of 1% of readings. The standard is capable of calibrating gas leak standards; gas leak detectors; micro-flow meters; flow nozzles; etc.

Micro- to Nano-Fluid Flow Standards  

Primary leak standard

Reference leak standard

Leak standard detectors

Air Velocity Standards

The air velocity in the wind tunnel is measured using a laser Doppler anemometer. The speed of small particles flowing with the air in the wind tunnel test section is detected by capturing the frequency of reflected light pulses when the particles pass through the laser fringes.

Air velocity meters can be calibrated in the range of 0.2 m/s to 60 m/s with the measurement uncertainty of 0.05% to 0.5% of reading. The standard is capable of calibrating air velocity standards, thermal anemometer, fan type Pitot tubes etc.

Air Velocity Standards  

DANTEC, FlowLite;
Wavelength of 532 nm;
Continuous output power of 200 mW

Air velocity meters

Air velocity meters used in the marine industry

Primary Liquid Flow Standard

The primary standard is developed to study novel measurement technology multiphase and high viscosity flow. The system measures and tests flowmeters using the static gravimetric measurement method.

Liquid flow meters can be calibrated in the range of 300 kg/h to 87,000 kg/h with measurement uncertainty of 0.05 %.

The standard is capable of calibrating most types of flow meters.

NMC collaborates with government agencies, manufacturers, and end users to conduct R&D works to explore measurement solutions for liquid flow measurement issues, and also provides consultancy and training on flow measurements.


Liquid flow measurement system

Static gravimetric standard 

R&D and Consultancy services

Primary Gas Flow Standard

The primary gas flow standards are established to calibrate all kinds of gas flow standards and meters in closed conduits, such as mass flow meter/controller, rotameter, turbine meter, sonic nozzle, ultra sonic flow meter and laminar flow meter, etc.

Gas flow meters can be calibrated with measurement uncertainty of 0.5 % in the low flow range of 1 sccm to 50,000 sccm and mid flow range of 3 to 110 m3.

Low-range primary gas flow standard

High-range primary gas flow standard

Transfer standards

Mass flow controller


Sonic nozzle

Gas meter

Ultrsonic flow meter

Primary Gas Pressure Standard

The primary pressure standard using the large area piston gauges of 35 mm and 50 mm generates precisely known pressure which is derived from loading masses and effective areas of piston & cylinder.
In order to acquire the accurate pressure, the piston and cylinders are precisely characterized. The new standards are capable of performing automatic calibration hence to reduce the possible human interference to the measurement and errors. The standards are able to calibrate absolute and relative pressure instruments.
Measurement range: 0.01 to 10 MPa
Measurement uncertainty: better than 30 ppm