Thermal Mass Flow Meter
Thermal Mass Flow Meter
From Sierra’s beginning over forty years ago, Founder Dr. John G. Olin was driven by the vision of supplying industrial customers with the world’s most accurate mass flow meter. And, he knew it was a “sensor” game.
The development of an industrialized metal-sheathed sensor in the early 80s was Sierra’s first big step, but Dr. Olin is a driven innovator, and this was only the beginning for someone who saw “Thermal Mass Flow” as his life’s work. Many successful innovations followed, but in 1999 Sierra experienced a major breakthrough with the introduction of their patented no-drift DrySense™ mass velocity sensor. Sierra engineers now recognized they were on the cusp of realizing Dr. Olin’s vision.
Realizing the Vision
Thermal technology, by its very nature, uses the physics of heat transfer and conservation of energy in an open system to measure mass flow rate. This means that for a thermal mass flow meter to achieve the greatest accuracy, it must solve the First Law of Thermodynamics (Heat Energy In = Heat Energy Out) for each data point.
As you can imagine, solving the First Law in a flow instrument was no easy task. By Dr. Olin’s own accounting, decades of “hard-nosed dedication to excellence” by himself and Sierra’s engineering team, years of testing, and his stack of yellow note pads over five feet high, jammed with his handwritten equations and designs, finally yielded the secret in the form of two revolutionary technologies— QuadraTherm® and qTherm™, now both patented worldwide.
QuadraTherm, Beyond Traditional Thermal
Traditional thermal sensors have two sensors-–one temperature sensor and one velocity sensor, each in a separate probe sheath. QuadraTherm (the term “Quad” meaning “four”) introduces four sensors—three precision platinum temperature sensors and one patented DrySense mass velocity sensor. Sensor performance improvements never thought possible are gained with QuadraTherm as forced convection is completely isolated (the critical variable for measuring gas mass flow rate) by calculating and then eliminating unwanted heat-transfer components, like sensor stem conduction, one of the major causes of false flow readings.
qTherm, the Brains Behind it
qTherm is the true “Brain” of the instrument and a revolutionary, living, learning algorithm set made possible by today’s hyper-fast microprocessors and QuadraTherm sensor inputs. qTherm manages changes in gas flow, gas temperature and gas pressure, as well as outside temperature, via a comprehensive heat-transfer model. The result is a proprietary, fundamentally different gas mass flow rate calculation using all pertinent variables for the most precise, stable and accurate mass flow measurement possible.
