Can anyone help me with viscosity conversion?

Question

I am working with a NGL pump which has been tested using water. I have a chart (which is logarithmic) for converting the viscosities. The viscosity for the fluid is in cP and the chart is in cS, and there are heaps of lines. I've haven't been this confused for years :) can anyone help?

Answer 1

Hope this would help u i know u know it but sometimes u have to read it and refresh ur mind

Units


[edit] Viscosity (dynamic/absolute viscosity): η or μ

The IUPAC symbol for viscosity is the Greek symbol eta (η), and dynamic viscosity is also commonly referred to using the Greek symbol mu (μ). The SI physical unit of dynamic viscosity is the pascal-second (Pa·s), which is identical to 1 kg·m−1·s−1. If a fluid with a viscosity of one Pa·s is placed between two plates, and one plate is pushed sideways with a shear stress of one pascal, it moves a distance equal to the thickness of the layer between the plates in one second. The name poiseuille (Pl) was proposed for this unit (after Jean Louis Marie Poiseuille who formulated Poiseuille's law of viscous flow), but not accepted internationally. Care must be taken in not confusing the poiseuille with the poise named after the same person!

The cgs physical unit for dynamic viscosity is the poise[1] (P; IPA: [pwaz])) named after Jean Louis Marie Poiseuille. It is more commonly expressed, particularly in ASTM standards, as centipoise (cP). The centipoise is commonly used because water has a viscosity of 1.0020 cP (at 20 °C; the closeness to one is a convenient coincidence).

1 P = 1 g·cm−1·s−1

The relation between Poise and Pascal-second is:

10 P = 1 kg·m−1·s−1 = 1 Pa·s
1 cP = 0.001 Pa·s = 1 mPa·s

[edit] Kinematic viscosity: ν

Kinematic viscosity (Greek symbol: ν) has SI units (m2·s−1). The cgs physical unit for kinematic viscosity is the stokes (abbreviated S or St), named after George Gabriel Stokes. It is sometimes expressed in terms of centistokes (cS or cSt). In U.S. usage, stoke is sometimes used as the singular form.

1 stokes = 100 centistokes = 1 cm2·s−1 = 0.0001 m2·s−1.
1 centistokes = 1 mm²/s

[edit] Dynamic versus kinematic viscosity

Conversion between kinematic and dynamic viscosity, is given by νρ = η. Note that the parameters must be given in SI units not in P, cP or St.

For example, if ν = 1 St (=0.0001 m2·s-1) and ρ = 1000 kg·m-3 then η = νρ = 0.1 kg·m−1·s−1 = 0.1 Pa·s [1].

For a plot of kinematic viscosity of air as a function of absolute temperature, see James Ierardi's Fire Protection Engineering Site

Answer 2

Check with the pump manufacturer....the manufacturer is always your best source of info for his product.