Inputs
Pipe Internal Diameter (Di) Int. Diameter (Di)
Particle Size (d50)
Solids Vol. Conc. (Cvd) Solids V. Conc. (Cvd) %
Liquid Dyn. Viscosity (μ) Liquid Viscosity (μ) Pa*s
Pipe Roughness (ε) mm
Absolute roughness values based on pipe material:
Material Roughness (mm)
Aluminium, copper, lead, brass 0.001-0.002
PVC and plastics 0.0015-0.007
Smooth Rubber 0.006-0.07
Stainless Steel 0.015
Steel Commercial Pipe 0.045-0.09
Stretched Steel 0.015
Weld Steel 0.045
Carbon Steel (New) 0.02-0.05
Carbon Steel (New) 0.02-0.05
Carbon Steel (New) 0.02-0.05
Carbon Steel (Worn) 0.05-0.15
Carbon Steel (Badly Corroded) 0.15-1
Cast Iron (New) 0.25-0.8
Cast Iron (Worn) 0.8-1.5
Cast Iron (Corroded) 1.5-2.5
Galvanized Iron 0.025-0.15
Smoothed Cement 0.3
Ordinary Concrete 0.3-1
Rough Concrete 0.8-3
Pipe Inclination (θ) deg.
Liquid SG (SGl)
Solids SG (SGs)
Model calibration parameters:
Use the following parameters to calibrate the model to fit your empirical findings, or leave default values to get a good estimate:
- Cvb: Volumetric concentration of solids in the bed that forms on the bottom of the pipe. 60% is a decent estimate for silica-based solids, but you can contact us to help you determine the exact value.
- μs: Friction coefficient between solids and pipe wall. Usually between 0.45 and 0.50.
Bed Vol. Conc. (Cvb) Bed V. Conc. (Cvb) %
Friction Coef. of S.B. (μs) FCSB (μs)
Results
Deposition Velocity Deposition Velocity - m/s
Max. Deposition Velocity Max. Dep. Velocity - m/s
The "max. deposition velocity" is a more conservative value for the limit deposit velocity, which takes into account the worst-case scenario for a given pipe diameter, and ensures that no deposition will occur.

On the other hand, the regular LDV is still an excellent estimate, but it is more sensible to changes in parameters such as delivered concentration or particle size.
About
What is this calculator based on?

This calculator is a direct port of the VSCALC function provided in the book "Slurry Transport Using Centrifugal Pumps". The VSCALC function combines Wilson's approximations for medium to coarse particles with the Thomas formula for fine particles.

What is the Limit Deposit Velocity?

The Limit Deposit Velocity (LDV) is defined as the line speed above which there is no stationary bed or sliding bed in a slurry. Below the LDV there may be either a stationary or fixed bed, or a sliding bed.

Why is the LDV important?

If a slurry is pumped under the LDV, depositions might be formed in the pipe which would result in an increase of the hydraulic gradient, and therefore a loss of efficiency in the system. Blockages in the system are also a possibility if the slurry velocity is too low.

Should the slurry be pumped at the maximum velocity to avoid deposition then?

Pumping slurries at excessively high velocities is not a good idea either, since the higher speeds could also result in increases of hydraulic gradient or, most importantly, significant increases in pipe wear.