Eldridge Products (EPI) manufactures a wide variety of thermal mass flowmeters for gas measurement and process control applications. Built with over 18 years experience in thermal mass flowmeter design and manufacture, EPI thermal mass flowmeters have earned a reputation for quality, dependability, ease of use and durability in real world industrial process gas applications. Its Master-Touch family of thermal mass flowmeters continued and greatly expanded upon this legacy by adding a powerful microprocessor to its proven thermal technology in order to give the product range a high degree of flexibility, accuracy and control.
The rate at which heat is absorbed by a gas flow stream is directly proportional to its mass flow. As the molecules of a moving gas come into contact with a heat source, they absorb heat and thereby cool the source. At increased flow rates, more molecules come into contact with the heat source, and absorb even more heat. The amount of heat dissipated from the heat source in this manner is thus proportional to the number of molecules of a particular gas (its mass), the thermal characteristics of the gas, and its flow characteristics. The rate at which heat is dissipated from the source is directly proportional to the mass flow rate of the gas, and by measuring the rate of heat dissipation, the mass flow of the gas can be accurately measured.
The heart of EPI's thermal gas mass flowmeters is the sensor design, which consists of two matched reference-grade platinum resistance temperature detectors (RTDs). The platinum sensing element wire is wound on a ceramic base, given a thin protective glass coating, and then encapsulated in a 316 stainless steel sheath, which is the only part of the sensor that is exposed to the gas stream, and which gives the sensor added strength and durability for the most arduous industrial processes.
A forced null Wheatstone Bridge preferentially heats up one RTD while the other RTD acts as a temperature reference by taking on the temperature of the flowing gas. The resistance ratios are maintained through the Wheatstone Bridge to compensate for the dynamic changes in the process temperature. By maintaining a constant temperature difference between the two RTDs, EPI is able to measure the amount of heat dissipated by the flowing gas stream. As heat is dissipated, more power is needed to maintain the constant temperature, with the power demand being directly proportional to the gas mass flow rate, thus allowing EPI's sensors to measure the gas molecular rate of flow without further compensation for outside effects. EPI's standard flow sensors can re-spond to flow velocities as low as 5 metres per minute and as high as 15 000 meters per minute for most gases.
Eldridge Products is represented in South Africa by C&F Technologies in Randburg.
| Tel: | +27 11 792 4588 |
| Email: | [email protected] |
| www: | www.flowmeters.co.za |
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