Products specs are divided to seven based on nominal line sizes: DN6, DN10, DN15, DN25, DN40, DN50, DN80, DN100 (units: mm).
     Selecting correct specs of mass flow meters is the base for safe operation and nicety measurement. Follow these selecting directions, could help you right use mass flow meters. Before selecting, should know parameters needed to select: flow range (maximum flow rate, rating flow rate, common use flow rate, minimum flow rate), line size (inner diameter, outside diameter), operation pressure, permission pressure drop, temperature of fluid, density (specific gravity) and viscosity of fluid, permission velocity of flow, accuracy. Further should know demands of real world installation: such as length of cable, signal format, demand for explosion-proof, environment and so on.
     （1） Primary select a nominal line size of mass flow meters
     User or engineer primary select a spec of mass flow meters base on flow range of fluid and inner diameter.
     Example: such as flow range: 8～20t/h, inner diameter: Φin = 50mm, viscosity of fluid: μ = 25cP, specific gravity: S = 0.8. So primary select DN50 mass flow meters, nominal line size: 50mm, maximum flow rate: 80t/h. (if user has known motive viscosity value mm2/s of fluid, could obtain absolute viscosity value μ with multiply by fluid density or specific gravity.)
     （2） Check pressure drop
     Reference the figure supplied by our company, there are curves of flow rate / pressure drop with different viscosity based on water (μ=1) of multi-specs of flow meters. In this example, find the point of 20t/h in the abscissa of the figure, draw a parallel with the ordinate through this point intersect with curve of μ= 25, got point Q, draw a parallel with the abscissa through the point Q intersect with the ordinate, got point P, we can read out point P pressure drop 0.08MPa.
     This pressure drop called figure pressure drop, sign as ΔPF = 0.08MPa.
     （3） Calculate real pressure drop using fluid specific gravity S
     Real pressure drop of fluid: ΔPR = ΔPF / S = 0.08MPa / 0.8 = 0.1MPa
     Commonly, this pressure drop would meet with demand of design and engineering. Next, check if tube pressure, temperature range meets with demands.
     （4） Check velocity of flow
     If there is the limit flow velocity by design and engineering, you have to calculate flow velocity using this formula:
     V = Kv × Qm / C.
     Herein: maximum flow rate Qm = 20 (t/h);
     Velocity parameter (see spec supplied by our company) Kv = 0.197 (h m/t s);
     Ratio of density of fluid by water (or specific gravity) C = S = 0.8.
     Then, got velocity: V = 20 ×0.197 / 0.8 = 4.925 m/s.
     For flammability and explosive chemical fluid, maximum velocity must lower the limit by safety and engineering, to avoid static high-voltage produced.
     （5） If viscosity more than 25cP, such as 500cP, then find pressure drop 0.8MPa at same flow rate reference the figure. If this pressure drop could not permit by design or engineering, must select a large line size of mass flow meters, such as DN80. Then repeat above（1）（2）（3）（4）to calculate and check.
     （6） After selecting right line size of mass flow meters, should check if measurement accuracy met the demands.
     Accuracy = ±[0.2% +（zero stability /flow rate×100%）]