RO System with 0.5t per Hour Output Capacity

Pipeline Resistance Calculation for RO Piping System

In principle, to determine the optimal pipe diameter, different flow velocities can be used as calculation scenarios to find the most economical and reasonable velocity or pipe size. For pipelines within a workshop, the flow rate can be empirically selected within the economical range, then the pipe diameter is calculated using the mass conservation formula and rounded according to pipeline standards.

Flow resistance is mainly composed of two parts:

1. Straight pipe resistance, which causes mechanical energy loss due to flow friction.

2. Local resistance, caused by elbows, valves, and other fittings.

In most cases, straight pipe resistance is negligible compared to local resistance.

In this design system, the target product water output is 0.5 t/h.

Reverse Osmosis Membrane Selection:

The selected membrane model is 4040, with a unit output capacity of 0.25 t/h.
Thus, two membranes are sufficient to meet the design capacity.

To ensure a stable output of 0.5 t/h:

• The feed flow for parallel configuration would be 3.125 t/h

• The feed flow for series configuration would be 1.7 t/h

Upon comparison, a series arrangement of the membrane modules is chosen to improve recovery rate for low-capacity systems.

• Inlet flow of RO system: 1.7 t/h

• Inlet flow of entire water treatment system: 2.0 t/h

• Operating conditions: 25 °C at 1 atm

  • Water viscosity: 0.8949 mPa·s

  • Water density: 997.13 kg/m³

Pressure Drop Across Each Equipment Unit:

Pump Selection and Head Loss Analysis:

The total head loss due to straight pipe and local resistance is calculated as Hf = 6.761 meters.
Therefore, the selected pump head must exceed this value.
The chosen water delivery pump model is 25GP-30, with a rated head of 30 meters.