This calculator is based on the DHLLDV Framework, a correlation model used to determine hydraulic gradients and Limit Deposit Velocities for slurries which aims to provide a combination of the most precise parts of all previous existing models in a single easy to use algorithm.
| 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 |
Check out our Concentration Conversion Calculator to convert between Cv and Cw.
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.
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.
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.
Experimental data (Graf & Robinson, 1970) shows that the LDV tends to decrease with increasing ascending pipe inclination. However, said experimental data is limited and only includes tests with small inclination angles. Therefore it is recommended that the angles used in this calculator are kept below 15 degrees.