How to Calculate Mining Hose Size, Flow Rate, and Pressure Drop

Choosing a mining hose size based only on nominal diameter can lead to inaccurate flow calculations, excessive pressure loss, or unnecessary liner wear. A reliable calculation should consider the required flow rate, actual internal diameter, operating velocity, hose length, conveyed material, elevation, fittings, and pressure conditions.

For liquid and slurry applications, the basic relationship is straightforward: flow rate depends on hose area and fluid velocity. Pressure drop then depends on the hose length, internal diameter, flow velocity, fluid density, and resistance from fittings and elevation.

This guide explains how to calculate mining hose size, flow rate, and pressure drop for preliminary system planning. It focuses mainly on water and slurry applications. Compressed air and other gases require separate compressible-flow calculations.

Before starting, it may be helpful to review what a mining hose is, including its liner, reinforcement, and outer cover construction.

Key Takeaways

• Use the actual internal diameter of the hose instead of relying only on the nominal hose size.

• Calculate hose diameter from the required flow rate and an appropriate operating velocity.

• Flow rate, velocity, and hose diameter are directly related through the hose cross-sectional area.

• Pressure drop includes straight-hose friction, fittings, elevation changes, and connected equipment.

• Slurry pressure drop cannot always be estimated accurately using water properties alone.

• A larger hose may reduce pressure loss, but the final choice must also consider pressure rating, vacuum resistance, bend radius, couplings, movement, and installation space.

• Use manufacturer pressure-drop data for final design whenever it is available.

Collect the Required Calculation Inputs

Before calculating, collect the operating data for the hose line. Missing or inaccurate inputs can make the result unreliable.

Use the normal flow rate and the expected maximum flow rate when possible. A hose that works at average flow may create excessive velocity or pressure loss when the system operates at peak capacity.

Determine the Required Flow Rate

The required flow rate normally comes from the pump, process equipment, dewatering requirement, or slurry transport capacity.

Common units include:

• Cubic meters per hour: m³/h

• Liters per minute: L/min

• Gallons per minute: gpm

Useful conversions include:

• 1 m³/h = 16.67 L/min

• 1 L/min = 0.06 m³/h

• 1 gpm ≈ 3.785 L/min

If the flow rate is already known from the pump or process design, use that value as the starting point. If the flow rate must be calculated from hose dimensions and velocity, use:

Q = v × A

The hose cross-sectional area is:

A = πD² / 4

Therefore:

Q = v × πD² / 4

Where:

• Q is the flow rate in m³/s

• v is the average fluid velocity in m/s

• D is the actual internal diameter in meters

• A is the internal cross-sectional area in m²

For practical calculations using millimeters and m³/h:

Q (m³/h) ≈ 0.00283 × D² (mm) × v (m/s)

For L/min:

Q (L/min) ≈ 0.0471 × D² (mm) × v (m/s)

These formulas show why a small change in internal diameter can produce a significant change in flow capacity.

Calculate the Required Mining Hose Diameter

When the required flow rate and design velocity are known, calculate the minimum internal diameter using:

D = √(4Q / πv)

For practical use:

D (mm) ≈ 18.8 × √[Q (m³/h) / v (m/s)]

Or:

D (mm) ≈ 4.61 × √[Q (L/min) / v (m/s)]

The result is the theoretical internal diameter required to carry the target flow at the selected velocity. It is not necessarily the final commercial hose size.

Example

Assume a slurry system requires:

• Flow rate: 90 m³/h

• Target velocity: 3.0 m/s

The required internal diameter is:

D ≈ 18.8 × √(90 / 3.0)

D ≈ 103 mm

This means a hose with an actual internal diameter of approximately 103 mm is required to transport 90 m³/h at 3.0 m/s.

A nominal 100 mm hose may have an actual internal diameter close to, but not exactly, 100 mm. At an actual 100 mm ID, the velocity would be approximately:

v = Q / A

v = 0.025 / (π × 0.1² / 4)

v ≈ 3.18 m/s

A 110 mm actual ID would reduce the velocity to approximately 2.63 m/s at the same flow rate.

The final choice depends on the acceptable velocity range, pressure-drop target, available hose sizes, installation space, and the characteristics of the conveyed slurry.

Choose an Appropriate Operating Velocity

Velocity should not be selected from hose diameter alone. It must match the conveyed material and the operating conditions.

A velocity that is too high may cause:

• Increased internal liner wear

• Greater pressure loss

• Higher pump energy consumption

• More severe erosion at bends and connections

• Increased pressure fluctuations

A velocity that is too low may cause:

• Solids settling in slurry lines

• Partial blockage

• Unstable discharge

• Increased cleaning or flushing requirements

• Poor transport performance

There is no single velocity that is suitable for every mining hose. The correct value depends on particle size, particle density, solids concentration, slurry viscosity, line layout, pump characteristics, and liner construction.

For abrasive slurry, the design should balance two competing requirements:

1. Maintain enough velocity to transport solids through the line.

2. Avoid unnecessarily high velocity that accelerates liner wear and pressure loss.

The velocity specified by the process engineer, pump supplier, or hose manufacturer should take priority over a general rule of thumb.

Recalculate the Actual Velocity for the Selected Hose

After selecting the nearest available hose size, recalculate the actual velocity. This step is important because the commercial hose size may not match the theoretical diameter exactly.

Use:

v = Q / A

Or:

v = 4Q / πD²

For a known flow rate of 90 m³/h:

• A 100 mm ID hose produces a velocity of approximately 3.18 m/s.

• A 110 mm ID hose produces a velocity of approximately 2.63 m/s.

• A 125 mm ID hose produces a velocity of approximately 2.04 m/s.

The result should then be checked against the process requirements. A larger hose is not automatically the correct choice if the lower velocity could allow solids to settle.

Always use the manufacturer’s actual internal diameter. The nominal size may not reflect the liner thickness, construction tolerance, or finished ID of the hose.

Calculate Pressure Drop in the Straight Hose

For a preliminary liquid-flow estimate, the Darcy-Weisbach equation can be used:

ΔP hose = f × (L / D) × (ρv² / 2)

Where:

• ΔP hose is the pressure drop in Pa

• f is the Darcy friction factor

• L is the hose length in meters

• D is the actual internal diameter in meters

• ρ is the fluid or slurry density in kg/m³

• v is the average velocity in m/s

The equivalent head loss is:

h f = f × (L / D) × (v² / 2g)

Where g is the gravitational acceleration, approximately 9.81 m/s².

The friction factor depends on:

• Reynolds number

• Fluid viscosity

• Internal surface roughness

• Hose liner material

• Flow conditions

• Slurry concentration and particle characteristics

For water, a friction factor may be estimated using standard fluid-flow methods. For slurry, the calculation is more complex because the mixture may not behave like a simple Newtonian liquid.

For this reason, manufacturer pressure-drop charts or test data are usually preferred for final mining hose design.

Include Fittings, Couplings, and Other Local Losses

The straight hose is only one source of pressure loss. Elbows, reducers, valves, couplings, flanges, strainers, and other components also resist flow.

Local pressure loss can be estimated using:

ΔP fittings = ΣK × (ρv² / 2)

Where:

• ΣK is the total loss coefficient for all fittings

• ρ is the fluid or slurry density

• v is the flow velocity

If the manufacturer provides a loss coefficient for a coupling, elbow, or reducer, use that value. If not, equivalent-length methods may be used for a preliminary estimate, but the result should be treated cautiously for flexible hose assemblies.

A hose installed with several tight bends may have a much higher pressure loss than the same hose installed in a straight line. The bend angle, bend radius, connection design, and transition between pipe and hose can all affect the actual result.

Account for Elevation and Equipment Pressure

The total pressure requirement may also include elevation and the pressure required by downstream equipment.

The static pressure associated with elevation is:

ΔP elevation = ρgh

Where:

• ρ is the fluid or slurry density

• g is 9.81 m/s²

• h is the vertical elevation change in meters

For an upward lift, elevation adds to the pump pressure requirement. For a downward section, the static contribution may reduce the required pump head, depending on the complete system layout. Friction losses remain present in either direction.

A practical system calculation should therefore consider:

ΔP total = ΔP hose + ΔP fittings + ΔP elevation + ΔP equipment

The equipment term may include the required inlet pressure, spray pressure, cyclone pressure, nozzle pressure, or other process requirement.

Do not treat hose friction loss as the same thing as the total pump pressure. The pump must overcome the complete system resistance and still provide the pressure required at the discharge point.

Special Considerations for Slurry Pressure Drop

Slurry pressure drop is affected by more than flow rate and hose diameter.

Important variables include:

• Bulk slurry density

• Solids concentration

• Particle size and shape

• Particle hardness

• Carrier-fluid viscosity

• Flow velocity

• Hose length

• Number of bends

• Elevation

• Internal liner condition

• Changes in hose diameter or direction

Using water density in a slurry calculation may significantly understate the pressure loss. A slurry with a high solids concentration may also have a different apparent viscosity and flow behavior from clean water.

Slurry can also settle when the velocity is insufficient. Once solids accumulate, the pressure drop may increase further and the line may become partially blocked.

For preliminary planning, the Darcy-Weisbach equation can provide a useful estimate if suitable slurry properties and a reasonable friction factor are available. For final design, use test data or manufacturer engineering support based on the actual slurry conditions.

If the application involves highly abrasive solids, review suitable slurry rubber hose options according to the required liner construction and operating conditions.

Worked Example: Comparing Two Hose Sizes

Consider a slurry line with the following conditions:

• Required flow rate: 90 m³/h

• Slurry density: 1,400 kg/m³

• Hose length: 30 m

• Upward elevation: 10 m

• Total fitting loss coefficient: K = 3.5

• Illustrative Darcy friction factor: f = 0.03

The flow rate is first converted:

90 m³/h = 0.025 m³/s

The theoretical ID at a target velocity of 3.0 m/s is approximately 103 mm. Compare two candidate hose IDs: 100 mm and 110 mm.

These values are illustrative estimates based on the stated assumptions. They do not replace manufacturer test data or a project-specific hydraulic calculation.

The 100 mm hose produces a higher velocity and higher estimated friction loss. It may still be suitable if the process allows that velocity and the pump has sufficient pressure capacity.

The 110 mm hose reduces velocity and estimated pressure loss, but it may not be the best choice if the lower velocity increases the risk of slurry settling. The final decision should therefore consider both hydraulic performance and solids-transport requirements.

Common Calculation Mistakes

Using Nominal Diameter Instead of Actual ID

The flow area is determined by the finished internal diameter, not the nominal size printed in the product name. Always confirm the actual ID from the technical data.

Mixing Flow Units

Using m³/h in a formula that requires m³/s can produce a result that is 3,600 times different. Convert all values before applying the basic equations.

Treating Slurry as Water

Water-based calculations may be acceptable for an initial comparison, but they can underestimate pressure loss in dense or viscous slurry.

Ignoring Fittings and Elevation

A long hose may not be the largest source of system resistance. Multiple bends, reducers, valves, and vertical lifts can add substantial pressure requirements.

Checking Only Normal Flow

Pump startup, valve closure, blockage, and process changes may create higher flow or pressure than normal operation. Consider peak and transient conditions.

Applying Liquid Formulas to Compressed Air

Air density changes significantly with pressure. A liquid-flow calculation should not be applied directly to compressed-air hose sizing.

Selecting a Hose Based Only on Flow

A hose may have the correct ID but still be unsuitable because of insufficient working pressure, vacuum resistance, temperature range, liner compatibility, bend radius, or coupling design.

A Practical Mining Hose Sizing Workflow

Use the following sequence for a preliminary calculation:

1. Define the normal and maximum required flow rate.

2. Identify the conveyed material and obtain its density and viscosity or slurry properties.

3. Select a process-appropriate velocity.

4. Calculate the theoretical internal diameter.

5. Compare the result with available hose IDs.

6. Recalculate the actual velocity for each candidate hose.

7. Estimate straight-hose pressure loss.

8. Add losses from fittings, couplings, valves, and reducers.

9. Add elevation and downstream equipment pressure requirements.

10. Check working pressure, vacuum rating, temperature, bend radius, movement, and coupling compatibility.

11. Confirm the final assembly with manufacturer data or engineering support.

For the broader application and assembly considerations, see how to choose the right mining hose assembly.

Conclusion

Calculating mining hose size starts with the relationship between flow rate, velocity, and actual internal diameter. Pressure-drop calculations must then include straight-hose friction, fittings, elevation, and the pressure required by connected equipment.

For water, standard fluid-flow equations can provide a useful preliminary estimate. For slurry, the result depends strongly on density, solids concentration, viscosity, particle behavior, and liner conditions, so manufacturer data should be used whenever possible.

If you are selecting a new hose or replacing an existing assembly, explore ZYfire's mining hose product range and provide the required flow rate, conveyed material, pressure, temperature, hose length, elevation, routing, and coupling details for a more suitable application match.

FAQ

How do I calculate mining hose size from flow rate?

Use the required flow rate and target velocity:

D = √(4Q / πv)

For practical metric calculations:

D (mm) ≈ 18.8 × √[Q (m³/h) / v (m/s)]

Always use the actual internal diameter when checking available hose sizes.

Does a larger mining hose always reduce pressure drop?

A larger hose generally reduces velocity and straight-hose friction loss at the same flow rate. However, it may also increase cost, weight, bend radius, and installation space. In slurry applications, an excessively large hose may reduce velocity enough to increase settling risk.

What is the difference between pressure drop and pump pressure?

Pressure drop is the pressure lost as the material moves through the hose, fittings, elevation changes, and other components. Pump pressure must cover these losses and still provide the pressure required by the downstream equipment.

Can I use a water pressure-drop calculation for slurry?

A water calculation can be used for an early comparison, but it may not represent the actual slurry pressure loss. Use the slurry density, viscosity, solids concentration, and manufacturer test data whenever possible.

Should I use nominal hose size or actual internal diameter?

Use the actual internal diameter for flow and pressure-drop calculations. Nominal size is useful for product identification, but the finished ID may vary with liner thickness and hose construction.

How should I size a hose for suction service?

Suction service requires a check of flow velocity, actual ID, vacuum rating, collapse resistance, pump inlet conditions, and available NPSH. A pressure-rated hose is not automatically suitable for vacuum or suction applications.

Can these formulas be used for compressed-air mining hoses?

Not directly. Air is compressible, so its density changes with pressure and temperature. Compressed-air sizing should use a suitable compressible-flow method and the hose manufacturer’s pressure-drop data.