MM2 Pressure



Pressure measurement is the analysis of an applied force by a fluid (liquid or gas) on a surface. Pressure is one of the derived values from mass, length and time. Pressure measurement and control is the most used process variable in the process control industry many segments. 

In addition, through the pressure it is possible infer a series of other process variables, like level, volume, flow and density. Hence, ensuring the measurements at each industrial application to be accurate is critical and significant. 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 Pressure & Flow Lab is expanding to cover the more areas such as the measurement of liquid density and the measurement of vacuum with a wider range. A density working standard traceable to the primary standard reference liquid is in the process of establishment, and a new vacuum system is also under construction.


The Pressure & Flow Laboratory at NMC has built the facilities for pressure, vacuum, gas, liquid, air velocity measurements and has proactively helped industry to solve industrial measurement issues through measurements and calibration services, consultancy and training as well as study for site measurement issues, developing measurement solutions in the area of pressure, vacuum, and fluid flow measurements. NMC develops, maintains and disseminates the pressure, vacuum fluid flow metrology related national measurement standards in Singapore.

Primary Gas Pressure Standards

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 can perform automatic calibration hence to reduce the possible human interference to the measurement and errors. The standards can calibrate absolute and relative pressure instruments.

Measurement range: 0.01 to 10 MPa
Measurement uncertainty: better than 30 ppm

Services Provided:

  • Pressure gauges and sensors

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

NMC Pressure standards include:

  • Deadweight pressure standard
  • Mercury manometer
  • Pressure gauges
  • Pressure indicators
  • Pressure reference standards

Services Provided:

  • Pressure reference standards and different types of pressure gauges.

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.

NMC Vacuum standards include:

  • Primary high vacuum standard
  • Vacuum gauges used for measurement of high vacuum systems
  • Vacuum gauges
  • Reference vacuum standards

Services Provided:

  • Vacuum reference standards and different types of vacuum sensors

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.

Primary liquid micro flow can calibrate the water flow rate range of 2 g/h to 180 g/h.

NMC Micro- to Nano-Fluid Flow Standards include:

  • Primary leak standard
  • Reference leak standard
  • Primary liquid micro-flow standard

Services Provided:

  • Calibration of gas leak standards, gas leak detectors and flow nozzles.
  • Calibration of different types of liquid micro-flow pumps and meters.

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 include

  • DANTEC, FlowLite; Wavelength of 532 nm; Continuous output power of 200 mW
  • Wind Tunnel Working Standard
  • Rotating Disk Primary Standard
  • Air velocity meters

Services Provided:

  • Calibration of different types of air velocity meters.

Primary Liquid Flow Standards

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

Primary Liquid Flow Standards include

  • Liquid flow measurement system
  • Static gravimetric standard

Services Provided:

  • Calibration of different types of liquid flow meters
  • R&D and Consultancy service

Primary Gas Flow Standards

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 0.7 % in the low flow range of 1 sccm to 50,000 sccm and mid flow range of 2 to 70 m3/h.

Primary Gas Flow Standards include

  • Low-range primary gas flow standard
  • High-range primary gas flow standard
  • Transfer standards

Services Provided:

  • Calibration of different types of gas flow meters
  • R&D and Consultancy service



The PL Laboratory also provides trainings on current and emerging technologies for pressure and flow measurements and monitoring. These trainings also act as a platform to educate scientists and engineers working in the fired on the fundamentals of pressure and flow metrology, and the importance of measurement comparability and traceability for international recognition of measurement and test results.

Trainings conducted in the past:

  • Pressure and Flow Measurement for Green Building
  • Advance Mass Flow Measurement Technology for Bunkering


To ensure the unbroken metrological traceability chain, the PL lab participated in several international comparisons in both the pressure and flow domains. NMC is the active member in the Asia Pacific Metrology Programme (APMP) Technical Committee for Fluid Flow (TCFF).

International measurement standards:

  • APMP.M.FF-K3 APMP Key Comparison for Air Speed
  • APMP.M.FF-K6.2010 APMP Key Comparison for Low-Pressure Gas Flow
  • APMP.M.FF-K6.2018 APMP Key Comparison for Low-Pressure Gas Flow
  • Bi-lateral Comparison for Liquid Flow (NMC and VSL)
  • Bi-lateral Comparison for Micro Liquid Flow (NMC and CMS)



The PL Laboratory also carries out R&D and consultancy for industry and other stakeholders to develop and apply pressure and flow measurement techniques for various applications.

Some of the projects in PL laboratory:

  • Natural gas transmission pipeline leakage detection
  • Technical advisory to design and build up a water flow calibration system
  • Venturi-Tube Calibration


movement birds 1

Have you ever wondered the movement of birds in the air?

The birds which are migrating from one place to another fly in groups. This can be explained by pressure and flow mechanism.

When a bird pushes its wings downward, a high pressure is formed below the wings. This high pressure moves to the low pressure and so the wings move upwards. This makes a bird to fly.

At the tip of bird’s wings, vortices are formed. The bird which is flying next gets a force from the vortices that are formed by the movement of wings of the first bird. So that, it need not have to put more force. Thus more energy is not required for the birds which are following the first bird.

For traveling long distances and to reduce the energy spent, birds use this technique of flying.