Thermal Mass Flow Meter

	Thermal Mass Flow Meter Thermal mass flow meters, also known as thermal dispersion or immersible mass flow meters, comprise a family of instruments for the measurement of the total mass flow rate of a fluid, primarily gases, flowing through closed conduits. A second type is the capillary-tube type of thermal mass flow meter. Many mass flow controllers (MFC) which combine a mass flow meter, electronics and a valve are based on this design. Furthermore, a thermal mass flow meter can be built by measuring temperature differential across a silicon-based MEMS chip. Both types measure fluid mass flow rate by means of the heat convected from a heated surface to the flowing fluid. In the case of the thermal dispersion, or immersible, type of flow meter, the heat is transferred to the boundary layer of the fluid flowing over the heated surface. In the case of the capillary-tube type, the heat is transferred to the bulk of the fluid flowing through a small heated capillary tube. The principles of operation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
picture info	Mass Flow Controller A mass flow controller (MFC) is a device used to measure and control the flow of liquids and gases. A mass flow controller is designed and calibrated to control a specific type of liquid or gas at a particular range of flow rates. The MFC can be given a setpoint from 0 to 100% of its full scale range but is typically operated in the 10 to 90% of full scale where the best accuracy is achieved. The device will then control the rate of flow to the given setpoint. MFCs can be either analog signal, analog or Digital data, digital. A digital flow controller is usually able to control more than one type of fluid whereas an analog controller is limited to the fluid for which it was calibrated. All mass flow controllers have an inlet port, an outlet port, a mass flow sensor and a proportional control valve. The MFC is fitted with a closed loop control system which is given an input signal by the operator (or an external circuit/computer) that it compares to the value from the mass flow sen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
	Fluid In physics, a fluid is a liquid, gas, or other material that continuously deforms (''flows'') under an applied shear stress, or external force. They have zero shear modulus, or, in simpler terms, are substances which cannot resist any shear force applied to them. Although the term ''fluid'' generally includes both the liquid and gas phases, its definition varies among branches of science. Definitions of ''solid'' vary as well, and depending on field, some substances can be both fluid and solid. Viscoelastic fluids like Silly Putty appear to behave similar to a solid when a sudden force is applied. Substances with a very high viscosity such as pitch appear to behave like a solid (see pitch drop experiment) as well. In particle physics, the concept is extended to include fluidic matters other than liquids or gases. A fluid in medicine or biology refers any liquid constituent of the body (body fluid), whereas "liquid" is not used in this sense. Sometimes liquids given for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
picture info	Moving Parts Machines include both fixed and moving parts. The moving parts have controlled and constrained motions. Moving parts are machine components excluding any moving fluids, such as fuel, coolant or hydraulic fluid. Moving parts also do not include any mechanical locks, switches, nuts and bolts, screw caps for bottles etc. A system with no moving parts is described as " solid state". Mechanical efficiency and wear The amount of moving parts in a machine is a factor in its mechanical efficiency. The greater the number of moving parts, the greater the amount of energy lost to heat by friction between those parts. For example, in a modern automobile engine, roughly 7% of the total power obtained from burning the engine's fuel is lost to friction between the engine's moving parts. Conversely, the fewer the number of moving parts, the greater the efficiency. Machines with no moving parts at all can be very efficient. An electrical transformer, for example, has no moving parts, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
picture info	Flow Conditioning Flow conditioning ensures that the “real world” environment closely resembles the “laboratory” environment for proper performance of inferential flowmeters like orifice, turbine, coriolis, ultrasonic etc. Types of flow Basically, Flow in pipes can be classified as follows – * Fully developed flow (found in world-class flow laboratories) * Pseudo-fully developed flow * Non-swirling, non-symmetrical flow * Moderate swirling, non-symmetrical flow * High swirling, symmetrical flow Types of flow conditioners Flow conditioners shown in fig.(a) can be grouped into following three types – * Those that eliminate swirl only (tube bundles) * Those that eliminate swirl and non-symmetry, but do not produce pseudo fully developed flow * Those that eliminate swirl and non-symmetry and produce pseudo fully developed flow (high-performance flow conditioners) Straightening devices such as honeycombs and vanes inserted upstream of the flow meter can reduce the length of straight p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]