RO Membrane Elements: Specifications and Selection Guide

Product Specifications

Technical details and manufacturing context for RO Membrane Elements

Definition

RO membrane elements are the essential filtration units within reverse osmosis systems that utilize semi-permeable membranes to remove ions, molecules, and larger particles from water under pressure. They are the primary components responsible for the desalination and purification process. These elements are constructed with a polyamide thin-film composite active layer, supported by a polysulfone layer and a polyester backing, providing mechanical strength and durability. The membrane area ranges from 7.2 to 37.2 m², and the permeate flow rate varies from 0.5 to 45.4 m³/d, depending on feed water quality and operating pressure. The salt rejection rate is typically between 99.2% and 99.8%, indicating high efficiency in removing dissolved salts. Operating pressure should be maintained between 1.0 and 1.6 MPa. The maximum operating temperature is 45°C, and exceeding this may damage the membrane. The continuous operation pH range is 2 to 11; outside this range, hydrolysis may occur. Feed water turbidity must not exceed 1.0 NTU, and the SDI (15 min) must be ≤5.0 to prevent colloidal fouling. Free chlorine tolerance is limited to 0.1 mg/L, as chlorine degrades the membrane. Standard dimensions are 1016 mm in length and 201 mm in diameter (8-inch element), with a dry weight ranging from 11 to 16 kg depending on the model. These elements are used in various applications, including desalination, wastewater treatment, and pure water production. When selecting an element, verify model-specific values and standards with the legal manufacturer or supplier, as the listed ranges are for reference only.

Working Principle

Water is forced under pressure against the semi-permeable membrane surface. The membrane allows water molecules to pass through while rejecting dissolved salts, organics, bacteria, and other contaminants, producing purified permeate water and concentrated reject water. The driving force is the applied pressure, which overcomes the osmotic pressure of the feed solution. The membrane's selective permeability is based on the size and charge of the solutes. As water flows through the element, the concentration of rejected solutes increases near the membrane surface, leading to concentration polarization, which must be managed by proper cross-flow velocity. The permeate is collected in a central tube, while the concentrate exits at the end of the element. The efficiency of separation depends on the membrane's properties, operating conditions, and feed water characteristics.

Common Materials

Polyamide thin-film composite, Polysulfone support layer, Polyester backing

Technical Parameters

Parameter	Typical range	Notes & selection driver
Membrane Area	7.2–37.2 m²	Determines water production capacity
Permeate Flow Rate	0.5–45.4 m³/d	Varies with feed water quality and pressure
Salt Rejection Rate	99.2–99.8 %	Higher is better for pure water
Operating Pressure	1.0–1.6 MPa
Maximum Operating Temperature	45 °C	Exceeding may damage membrane
pH Range (Continuous Operation)	2–11	Outside range may cause hydrolysis
Maximum Feed Water Turbidity	1.0 NTU	Higher turbidity causes fouling
Maximum Feed Water SDI (15 min)	5.0	SDI >5 leads to colloidal fouling
Free Chlorine Tolerance	0.1 mg/L	Chlorine degrades membrane
Dimensions (Length × Diameter)	1016 × 201 mm	Standard 8-inch element
Weight	11–16 kg	Dry weight, varies with model

Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.

Components / BOM

Membrane Leaves Part
Active filtration layers where separation occurs

Material: Polyamide thin-film composite
Feed Spacer Part
Creates flow channels for feed water distribution across membrane surface

Material: Polypropylene
Permeate Spacer Part
Collects and channels purified water to the central tube

Material: Polyester
Central Tube Part
Collects and transports purified water from the membrane element

Material: ABS plastic
Anti-telescoping Device
Prevents membrane shifting under high pressure

Material: Fiberglass reinforced plastic

Applied To / Applications

This component is essential for the following industrial systems and equipment:

Reverse Osmosis Unit

View system integration details

Manufacturers of RO Membrane Elements

Manufacturer profiles associated with RO Membrane Elements.

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Frequently Asked Questions

What is the typical salt rejection rate for RO membrane elements?

The salt rejection rate typically ranges from 99.2% to 99.8%, depending on the membrane type and operating conditions. Higher values indicate better removal of dissolved salts.

What is the maximum operating temperature for these elements?

The maximum operating temperature is 45°C. Exceeding this limit can damage the membrane structure and reduce performance.

What feed water quality parameters are critical for RO membrane operation?

Key parameters include turbidity (max 1.0 NTU), SDI (max 5.0), and free chlorine (max 0.1 mg/L). High turbidity or SDI can cause fouling, and chlorine degrades the membrane.

How do I select the right RO membrane element for my application?

Selection depends on required permeate flow, feed water quality, and system design. Consider membrane area, flow rate, and rejection rate. Always verify model-specific specifications with the manufacturer or supplier.

Data Basis

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Preliminary Technical Classification

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pH range:	2-11 (continuous), 1-12 (cleaning)
pressure:	Max 1000 psi (69 bar)
flow rate:	8-16 GPM per 8-inch element
temperature:	5-45°C (41-113°F)
slurry concentration:	Max 1.0% TSS

RO Membrane Elements

Product Specifications

Applied To / Applications

Industrial Ecosystem & Supply Chain Structure

Application Fit & Sizing Matrix

Reliability & Engineering Risk Analysis

Compliance & Manufacturing Standards