National Physical Laboratory (NPL) is the National Metrology Institute (NMI) of India. It is the custodian of physical parameters of national standards. The objective of the Fluid Flow Measurement Standards Group of National Physical Laboratory is to establish, maintain and upgrade primary and secondary standards of fluid flow and provide traceable calibration service to various users in the country.

The water meter testing facility is used for testing domestic water meters of sizes DN15 to DN50 as per IS 779, IS 6784 and ISO 4064 standards and is also used for calibration of rotameters. It is based on the standing start and standing finish system. It uses two scales of 150 and 1500 kg capacity. It has 1, 3 and 7.5 HP pumps to supply the required flow in the range of 0-30,000 lph for testing of water meters and calibration of rotameters. Flow in the line is monitored by electromagnetic flowmeter and rotameter. The feature uncertainties in the total volume and volume flow rate are 0.10 and 0.25% (at k = 2), respectively. Rotameters are calibrated by the weighing method at low flow rates (up to 1000 lph), while at high flow rates (above 1000 lph), they are calibrated by the comparison method by employing electromagnetic flowmeters of DN25 and DN50 sizes as reference standards. is calibrated. The accuracy of the water meters/flowmeters tested/calibrated at this facility is in the range of 2-5%. Water meters (called bulk water meters) up to DN50 and up to DN200 sizes are tested in the primary water flow calibration facility. Figure shows a schematic diagram of the facility.

Domestic Water Meter Testing Facility

NPLI being the NMI of the nation is entrusted with the responsibility of establishing, maintaining, upgrading and disseminating the National Flow Standards in India. The WFCF at CSIR-NPL was designed as per ISO 4185 standard. It was established between 1992 and 1998 as a part of the NPLI-PTB technical cooperation programme. The facility had 2 test rigs with nominal diameters of 50 mm and 200 mm for calibration of WFM. The facility was operational until 2001. Although automated operation was beneficial, very complex operations began to experience regular issues. The operational functioning of both the test rigs was later restored between 2008 and 2009. In addition, most of the component parts, control systems and equipment used were obsolete. As a result, system improvements were planned to improve this facility using advanced measurement techniques, achieving uncertainty levels comparable to international standards in the water flow field.

This facility is designed and manufactured for the design and calibration of various types of flow meters up to DN300 using 12 kg, 300 kg, 3000 kg and 6000 kg systems in the flow range of 0.3 m³/h to 650 m³/h as per ISO 4185 standard. has been developed. In the flow range up to 530 m³/h, the extended uncertainty in flow meter calibration in totalizer mode is found to be ±0.01% to ±0.025% (k=2), while the mass flow in the flow range from 0.1 m³/h to 650 m³/h For flow rate (MFR) and volume flow rate (VFR) up to DN300 size, it is ±(0.03-0.05) % (k=2). The obtained measurement uncertainty is comparable to the state-of-the-art water flow measurement capabilities available at several National Metrology Institutes (NMI). Thus, the present designed and developed system at CSIR-National Physical Laboratory (CSIR-NPL) is a solution for users and industries to maintain the traceability.

Schematic Diagram of the Water Flow Calibration Facility Designed at CSIR-NPL

Primary Water Flow Calibration Facility

Over the past decade, low fluid flow measurement has become increasingly important. Accurately detecting and controlling low flow rates is a common challenge during medical operations and treatments. Syringes and infusion pumps are often used in hospitals and research laboratories for accurate and precise drug dosing for cancer patients undergoing chemotherapy, among other important applications. Syringe pumps and infusion pumps typically use liquid flow rates of less than 1500 ml/h. Syringe Pump, Infusion Pump, and Infusion Device Analyzer calibrations have been in high demand in India during the past few years. For such a solution, the Fluid Flow Metrology Section of CSIR-National Physical Laboratory (CSIR-NPL), New Delhi, in the range of 5 ml/h to 1500 ml/h, with an extended uncertainty (at k = 2) has proposed a total Set up a low liquid (micro liquid flow) calibration facility, in the range of 0.40% to 0.60% for volume and 0.50% to 1.0% for volume flow rate. This facility utilizes a static weighing method and a 220 g/82 g (dual range) weighing balance. The present study shows the detailed design and development and metrological quantification of the established facility. In addition, the Fluid Flow Working Group at CSIR-NPL aims to improve physical models, conduct research on small fluid flows, and develop best practices for measuring microscopic flows. CSIR-NPL has developed a primary standard which gives an extended uncertainty in the range of 0.40% to 0.60% (at k = 2) for total volume and an extended uncertainty in the range of 0.50% to 1.0% (at k = 2) for volume. For flow rates, covers a flow rate range of 5 ml/h to 1500 ml/h. This facility uses a 220 g/82 g (dual range) weighing balance and the static weighing method is used, as shown in Figure.

Photograph of CSIR-NPL facility with main components: syringe pump, infusion device analyzer (IDA), beaker on balance, weighing balance

Internal users of National Physical Laboratory (such as Department of Chemical Metrology, Solar Photovoltaic Group, Department of Radio and Atmospheric Sciences) and external users; Like Pollution Control Board, Pharmaceutical Laboratory, Research & Development Laboratory and NABL. Keeping in view the requirements of the accredited laboratories, a gas flow calibration system has been set up at the Liquid Flow Laboratory of the National Physical Laboratory. Its flow range is from 10 sccm to 1000 slm and its extended uncertainty is 0.2% at k=2. The system supports multigas calibration. It can calibrate various types of instruments like mass flow controllers, mass flow meters, rota meters, totalizer type meters, precision laminar and sonic flow meters etc. In the present article various parts of this system are described. The uncertainty in the measurement has been calculated according to the ISO ‘GUM’ document.

Gas Flow Calibration Facility

Dr. Shiv Kumar Jaiswal
Chief Scientist
Fluid Flow Measurement Metrology Section
Email: skjaiswal@nplindia.org
Phone : +91 1145609426