How tekMass Operates
tekMass embodies 2 high stability thermal sensors, either for insertion into a pipe or duct, under pressure if necessary. Alternatively, it may be supplied as an in-line sensor, complete with spool piece and process flanged connections. They are only suitable for gas flow, not including steam.
One sensor is heated and the other is a reference. The reference sensor resistance is accurately maintained and the power required to provide a constant temperature between the heated sensor and the reference sensor is a measurement of the mass flow of the gas flowing past the 2 sensors.
tekMass is normally calibrated on air, or the application gas, against a pressure and temperature compensated sonic nozzle to ISO9300 with an accuracy of 0.2% of reading. This is an internationally recognized primary standard.
On some occasions, for example exotic or mixed gases, the calibrated air mass flow can be corrected by determining the square root of the product of the thermal conductivity and density of the particular application gas. A customized NIST traceable Calibration Certificate is provided for each tekMass, expressed in either volumetric flow corrected to normal NTP conditions or in mass flow units.
The overall accuracy of tekMass, including corrections where necessary, and the sonic nozzle, is < ± 1% of reading, or ± 0.5% of full scale, whichever is the greater.
Why Use tekMass – Some Useful Facts
It is obvious why tekMass should play an enormous role in both money saving and in protection of the environment. Please consider:
+ A I kg mass of methane gas has 28 times greater influence on global warming than 1 kg of carbon dioxide, but both play a major role in global warming. (Energy Institute of Haas, University of California, Berkeley)
+ Methane gas leaking from natural gas systems represents 2.8% of the total energy related world’s greenhouse gas emissions. (USA Environmental Protection Agency)
+ The value of natural gas lost through pipe leakage is US $300 million per annum using 1996 average costs. Applying a “social cost” of US $37 per normal metric USA ton of carbon dioxide, the cost of leaked gas exceeds US $2 billion per annum. (USA Department of Environment)
+ It is incumbent on utilities world-wide involved with biogas, methane, carbon dioxide and natural gas to accurately monitor both ends of pipeline carriers to determine how much leakage occurs and to use the results to ensure minimal or zero leakage. With tekMass such leakage is detected at typically within 1% NIST traceable accuracy. This 1 % applied to
US $300 million natural gas lost per year represents an annual saving of US 297 million.
+ Large savings can be demonstrated using simple compressed air applications.
Example: A typical compressor uses 50kWh and produces 480 nm3/h air.
Therefore, 1 nm3/h consumes 50 / 480 = 0.104 kWh
Assume average electricity costs are US $0.137 / kWh
The cost of electricity = 0.104 kWh / nm3 x US $0.137 = US $0.0143 / nm3
To arrive at a more truthful amount, the compressor industry estimates an average 70% due to the compressor, the total being the additional costs of maintenance, installation, etc.
Therefore a more accurate cost would be US $0.0143 / 0.7 = US $0.0204/nm3
Taking a typical example of a 100mm pipe delivering 1000 nm3/h, the cost would be
US $0.0204 x 1000 nm3/h = US $20.4 / h = US $178700 per year.
The USA Department of Energy estimates most compressed air plants are operating at 10% leakage. From the figure above this represents a loss of US $17870 per annum
With serious leak remediation and using a tekMass TMS to show leakage to a known and traceable 1% represents a saving of US $178700 – US $1787 = US $176900 per annum.
Presented by: Dr Robert Batey