How to Calculate Clean Rate from Slurry Rate – Cost Calculator

Slurry to Clean Rate Calculator

Total Slurry Flow Rate (GPM or m³/h)

Concentration of Solids by Weight (%)

Specific Gravity of Solids (e.g., 2.65 for Sand)

Specific Gravity of Liquid (Water = 1.0)

Calculation Results:

Clean Liquid Flow Rate: 0

Dry Solids Flow Rate: 0

Concentration by Volume: 0 %

Mixture Specific Gravity: 0

Understanding Slurry vs. Clean Rate Calculations

In industrial pumping, dredging, and mineral processing, "slurry" refers to a mixture of solid particles and a carrier liquid (usually water). Calculating the clean rate—the flow rate of the liquid component alone—is critical for sizing pumps, managing water balances, and determining the efficiency of solid-liquid separation processes.

The Physics of Slurry Concentration

Slurry concentrations are usually measured by weight ($C_w$), but hydraulic calculations require understanding the volume ($C_v$). Because solids are typically denser than the liquid they are suspended in, 30% solids by weight does not mean 30% of the volume is occupied by solids.

The Formulas Used

To find the clean rate, we first determine the Mixture Specific Gravity ($S_m$) and the Concentration by Volume ($C_v$):

Mixture SG ($S_m$): $100 / [ (C_w / S_s) + ((100 – C_w) / S_l) ]$
Concentration by Volume ($C_v$): $C_w \times (S_m / S_s)$
Dry Solids Flow: $Total Flow \times (C_v / 100)$
Clean Rate (Liquid Flow): $Total Flow – Dry Solids Flow$

Example Calculation

Suppose you have a dredging operation with the following parameters:

Total Slurry Flow: 1,000 GPM
Concentration by Weight: 25%
Specific Gravity of Sand: 2.65
Specific Gravity of Water: 1.0

First, we calculate the Mixture SG, which would be approximately 1.18. Then, the concentration by volume ($C_v$) is calculated to be roughly 11.16%. This means that of the 1,000 GPM flowing through the pipe, 111.6 GPM is solid sand, and the Clean Rate (water flow) is 888.4 GPM.

Why This Matters

Identifying the clean rate helps engineers determine the actual volume of water being moved, which is essential for calculating friction loss. Since solids don't behave like liquids, the "clean" portion of the flow is what carries the kinetic energy required to keep the solids in suspension (preventing pipe blockage).

function calculateSlurryMetrics() { var flow = parseFloat(document.getElementById('slurryFlow').value); var cw = parseFloat(document.getElementById('concentrationWeight').value); var ss = parseFloat(document.getElementById('sgSolids').value); var sl = parseFloat(document.getElementById('sgLiquid').value); if (isNaN(flow) || isNaN(cw) || isNaN(ss) || isNaN(sl) || flow <= 0 || ss <= 0 || sl = 100) { alert("Concentration by weight must be less than 100%."); return; } // Calculate Mixture Specific Gravity (Sm) // Formula: Sm = 100 / ( (Cw/Ss) + ( (100-Cw)/Sl ) ) var sm = 100 / ((cw / ss) + ((100 – cw) / sl)); // Calculate Concentration by Volume (Cv) // Formula: Cv = Cw * (Sm / Ss) var cv = cw * (sm / ss); // Calculate Solids Flow Rate var solidsFlow = flow * (cv / 100); // Calculate Clean Rate (Liquid Flow Rate) var cleanFlow = flow – solidsFlow; // Display Results document.getElementById('slurryResult').style.display = 'block'; document.getElementById('cleanRateResult').innerText = cleanFlow.toFixed(2); document.getElementById('solidsRateResult').innerText = solidsFlow.toFixed(2); document.getElementById('volumeConcResult').innerText = cv.toFixed(2); document.getElementById('mixtureSGResult').innerText = sm.toFixed(3); }