Understanding centipoises to pounds per foot-second Conversion
The centipoise (cP) is the common metric-derived unit of dynamic viscosity, with water sitting near 1 cP. The pound per foot-second (lb/(ft·s)) is the US customary absolute-viscosity unit built from mass, length, and time, and it is large — one lb/(ft·s) equals roughly 1488 cP. Converting centipoises to pounds per foot-second is needed when fluid-mechanics problems in American textbooks and process software use the foot-pound-second (FPS) system, particularly in chemical and petroleum engineering flow calculations.
Conversion Formula
To convert centipoises to pounds per foot-second, multiply by this factor:
Step-by-Step Example
Convert 25 centipoises to pounds per foot-second.
How to Convert centipoises to pounds per foot-second
Use this to move a metric viscosity reading into the US customary FPS system.
- Start with centipoises: Take the value in cP, for example 25 cP.
- Multiply by 0.000671969: This is the number of lb/(ft·s) in one centipoise.
- Work out the product: .
- Give the answer: 25 centipoises equals about 0.0167992 pounds per foot-second.
centipoises to pounds per foot-second conversion table
| centipoises (cP) | pounds per foot-second (lb/(ft-s)) |
|---|---|
| 0 | 0 |
| 1 | 0.000671969 |
| 2 | 0.001343938 |
| 3 | 0.002015907 |
| 4 | 0.002687876 |
| 5 | 0.003359845 |
| 6 | 0.004031814 |
| 7 | 0.004703783 |
| 8 | 0.005375752 |
| 9 | 0.006047721 |
| 10 | 0.00671969 |
| 15 | 0.01007953 |
| 20 | 0.01343938 |
| 25 | 0.01679922 |
| 30 | 0.02015907 |
| 40 | 0.02687876 |
| 50 | 0.03359845 |
| 60 | 0.04031814 |
| 70 | 0.04703783 |
| 80 | 0.05375752 |
| 90 | 0.06047721 |
| 100 | 0.0671969 |
| 150 | 0.1007953 |
| 200 | 0.1343938 |
| 250 | 0.1679922 |
| 300 | 0.2015907 |
| 400 | 0.2687876 |
| 500 | 0.3359845 |
| 600 | 0.4031814 |
| 700 | 0.4703783 |
| 800 | 0.5375752 |
| 900 | 0.6047721 |
| 1000 | 0.671969 |
| 2000 | 1.343938 |
| 3000 | 2.015907 |
| 4000 | 2.687876 |
| 5000 | 3.359845 |
| 10000 | 6.71969 |
| 25000 | 16.79922 |
| 50000 | 33.59845 |
| 100000 | 67.1969 |
| 250000 | 167.9922 |
| 500000 | 335.9845 |
| 1000000 | 671.969 |
What is the centipoise?
The centipoise (cP) is a CGS unit of dynamic (absolute) viscosity, equal to one hundredth of a poise. It is the most widely used practical viscosity unit in industry because water at about 20 °C has a viscosity of very nearly 1 cP.
Definition
One centipoise equals one hundredth of a poise, which in SI units is exactly one millipascal-second:
Since (the poise being defined as ), the centipoise is of that, i.e. exactly. The unit is dimensionally mass per length per time.
Origin and History
The poise is named after the French physician and physiologist Jean Léonard Marie Poiseuille (1797–1869), who studied the flow of liquids (blood) through narrow tubes and formulated what became the Hagen–Poiseuille law. The centipoise arose as a convenient submultiple because water conveniently sits near 1 cP, making comparisons intuitive.
Law and Notable Facts
The centipoise is a CGS-derived unit and is not part of the SI, which prefers the pascal-second (Pa·s) or millipascal-second (mPa·s). Because exactly, conversion between the everyday industrial unit and the SI unit requires no arithmetic beyond a change of name — a coincidence that has helped the centipoise survive.
Real-World Examples and Conversions
Water at 20 °C is about 1.002 cP. Whole milk is roughly 3 cP, olive oil around 60–80 cP, and honey near 2,000–10,000 cP. SAE 30 motor oil at 20 °C is on the order of 200 cP. To convert, .
What is the pound per foot-second?
The pound per foot-second (lb/(ft·s)) is a unit of dynamic (absolute) viscosity in the English absolute (mass-based) system, where the pound is treated as a unit of mass (pound-mass). It is the FPS analogue of the poise, which is the gram per centimetre-second.
Definition
One pound per foot-second is the viscosity of mass one pound-mass flowing through one foot per second:
The exact value comes from and , giving . This is the pound-mass form and must not be confused with the gravitational pound-force-second per square foot, which is about 32.174 times larger.
Origin and History
This unit arises from the English absolute (or "poundal") system of mechanics, in which mass is the base quantity and force is the derived poundal. It appears in older engineering and chemical-engineering literature, particularly British texts, as a direct mass-based counterpart to the CGS poise.
Law and Notable Facts
It is not an SI unit. A useful relationship: , and the difference between this mass-based unit and the force-based lbf·s/ft² is exactly the standard gravitational conversion factor (the ratio of pound-force to poundal).
Real-World Examples and Conversions
Water at 20 °C () is about . A fluid of is roughly as viscous as light honey. Motor oil around is about .
Frequently Asked Questions
How many pounds per foot-second are in one centipoise?
One centipoise equals about 0.000671969 lb/(ft·s), a small fraction because the FPS unit is much larger.
How many centipoises equal one pound per foot-second?
About 1488 centipoises make one lb/(ft·s), the reciprocal of the forward conversion factor.
What kind of unit is the pound per foot-second?
It is an absolute (dynamic) viscosity unit in the US customary foot-pound-second system, expressing mass flow resistance directly rather than through pound-force.
What is 25 cP in pounds per foot-second?
Multiply 25 by 0.000671969 to get about 0.0167992 lb/(ft·s).
In which fields is this conversion common?
It shows up in American chemical and petroleum engineering, where pipe-flow, pumping, and heat-transfer correlations are often written in FPS units.
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Complete centipoises conversion table
| Unit | Result |
|---|---|
| pascal-seconds (Pa-s) | 0.001 Pa-s |
| millipascal-seconds (mPa-s) | 1 mPa-s |
| poises (P) | 0.01 P |
| pound-force-seconds per square foot (lbf-s/ft2) | 0.00002088543 lbf-s/ft2 |
| pounds per foot-second (lb/(ft-s)) | 0.000671969 lb/(ft-s) |