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Rotating Cylinder Pipe Velocity to Rotation Rate Calculator

Rotating Cylinder Pipe Velocity to Rotation Rate Calculator

This tool correlates Rotating Cylinder Electrodes (RCE) rotation rate to pipe velocity. Commonly, labs that evaluate pipeline corrosion inhibitors do so in the laboratory. The rotation rate of the RCE should be tuned to match the representative pipe velocity. Users are encouraged to review the Study of Mass Transport Limited Corrosion with Rotating Cylinder Electrodes support article to learn the origin of the equations and relationships used in this calculator. NOTE: This tools has been provided free or charge to the greater corrosion community. We have taken care to carefully code the utility; however, we make no claim to the accuracy of the results. Users in need of analytical certainty must derive their own equations and calcaulte their own values.

This tool provides three different computed outputs and a reference table, as follows:

  • Calculator : Calculate RCE Rotation Rate from Pipe Velocity
  • Calculator : Calculate Pipe Velocity from Pipe ID and Rotation Rate
  • Calculator : Calculate RCE Rotation Rates from a Select List of Pipe Velocity for Common Schedule 40 Pipe Sizes
  • Reference Table : Hydrodynamic Computations
Do not exceed maximum rotation rate!

Pine Research specifies maximum rotation rates for all rotating electrodes.
The maximum rotation rate of the 15 mm OD RCE (E9 Series) is 4000 RPM.
The maximum rotation rate of the 12 mm OD RCE (QC012 Series) is 2000 RPM.
Never exceed the specified maximum rotation rate.

How to Use this Calculator

  1. Choose the RCE electrode in the Rotating Cylinder Electrode (RCE) Selection section.
  2. Enter the system variables in the System Specific Variables section.
  3. Open Calculators , , or to view results.
  4. Click the Start Over button at any point to reset all selections and input variables.Start Over

Rotating Cylinder Electrode (RCE) Selection

To begin, select the Rotating Cylinder Electrode (RCE) you plan to use, for which this tool will compute values linking pipe velocity and rotation rate. After selecting an RCE, the table will display the dimensions of the cylinder inserts used with the selected shaft, whose values are used in the calculators.

15mm OD RCE Electrode - E9 Series
12 mm OD RCE Electrode - QC012 Series
Term
Value
Unit
Symbol

System Specific Variables

Please provide values for the following variables. We provide you with some common values for each variable (for water) in the Notes column. You may enter values with scientific notation using the format 1.2e-6 for 1.2 × 10-6, for example.

Click the Water Defaults button to automatically fill in the values below for pure water. Water Defaults

Term
Value
Unit
Symbol
Notes
Concentration
mol/cm3
C
bulk concentration, assume 1e-6 for pure water
Density
g/cm3
ρ
of the solution, 0.99713 for pure water at STP
Absolute Viscosity
g/cm s
μ
Assume 0.00891 for pure water at STP
Diffusion Coefficient
cm2/s
D
Assume 1e-5 for pure water at STP
# Electrons
-
z
Set by reaction (n = 1 default)

This calculator allows you to input a desired pipe velocity and compute the RCE rotation rates necessary to achieve it, as a function of some common Schedule 40 Pipe Types. First, select your RCE. Then, provide System Specific Variables. Finally, enter the desired velocity (choose any unit, the others will be calculated for you) and press the Compute button to generate the data in the table below.

Pipe Velocity

ft/s
cm/s
mi/hr
Pipe Velocity
Schedule 40 Pipe Type (Pipe ID)
ft/s
cm/s
mi/hr
1 in
2.667 cm
2 in
5.2578 cm
3 in
7.7978 cm
4 in
10.2362 cm
5 in
12.827 cm
6 in
15.4178 cm
8 in
20.2692 cm
10 in
25.4508 cm
12 in
30.3276 cm
14 in
33.3502 cm
16 in
38.1 cm
18 in
42.8752 cm
20 in
47.7774 cm
24 in
57.4802 cm

This calculator allows you to input a specific Pipe Type (pipe ID) and RCE rotation rate to calcualte the pipe velocity. First, select your RCE. Then, provide System Specific Variables. Finally, enter the specific pipe inner diameter (ID) in cm and the RCE rotation rate in RPM and press the Compute button to generate the data in the table below.

Pipe ID and Rotation Rate

Inner Diameter
cm
Rotation Rate
RPM
Pipe Velocity
ft/s
cm/s
mi/hr

Computation Output

The table below shows RCE rotation rates, for the selected RCE, required to achieve the pipe velocity across several common Schedule 40 Type Pipes. The Rotation Rates are a function of the RCE diameter, System Specific Variables, and Pipe Velocity as described in our support article, Study of Mass Transport Limited Corrosion with Rotating Cylinder Electrodes.

Pipe Velocity
Schedule 40 Pipe Type (Pipe ID)
ft/s
cm/s
mi/hr
1 in
2.67 cm
2 in
5.26 cm
3 in
7.80 cm
4 in
10.24 cm
5 in
12.83 cm
6 in
15.42 cm
8 in
20.27 cm
10 in
25.45 cm
12 in
30.33 cm
14 in
33.35 cm
16 in
38.10 cm
18 in
42.88 cm
20 in
47.78 cm
24 in
57.48 cm

The table below shows the computed hydrodynamic values for the selected RCE electrode, based on the RCE diameter, System Specific Variables you provided above.

Rotation Rate
(RPM)
Rotation Rate
(radians/s)
Surface Velocity
(cm/s)
Reynolds Number
(unitless)
Wall Shear Stress
(g/cm s2)
Wall Shear Stress
(kg/m s2)
Mass Transfer Coefficient
(cm/s)
Limiting Current
(A)
Limiting Current Density
(A/cm2)

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