In water treatment and in the chemical industry, pumping highly reactive substances requires technological solutions specifically designed for the characteristics of different fluids. One of the fundamental elements of these processes is the sodium hypochlorite pump, a critical investment for safety, regulatory compliance, and process continuity in companies operating in these sensitive and highrisk sectors.
For pumping a substance such as sodium hypochlorite, every design choice—from the pump casing material to the type of sealing system, from the impeller geometry to the transmission solution—directly affects plant productivity and efficiency, contamination risks, and medium to longterm operating costs.
For aggressive and oxidising liquids like hypochlorite, CDR Pompe offers the ETN EVO, a lined magneticdrive pump designed to minimise leakage and extraordinary maintenance, ensuring consistent performance in both discontinuous and continuous service.
Chemical characteristics of sodium hypochlorite: properties, stability and risks
Sodium hypochlorite (NaClO) is widely used for its disinfecting and oxidising properties, but it also presents hazards if not handled correctly. In aqueous solution it is strongly alkaline and chemically unstable: its equilibrium can be altered by temperature changes, light, or contact with incompatible materials, particularly metals.
When these conditions are not controlled, hypochlorite tends to degrade, losing effectiveness and generating unwanted byproducts, including chlorine gas.
From a safety standpoint, sodium hypochlorite is classified as a corrosive substance: direct contact can cause skin and eye irritation, while inhalation of vapours or accidentreleased chlorine gas poses serious respiratory risks. For this reason, it is essential to avoid leaks and weak points in industrial pumping systems.
Its environmental impact must also be considered: accidental spills can damage aquatic ecosystems and react with organic compounds to form persistent chlorinated substances.
All these factors make it clear that handling this fluid requires pumping solutions designed to guarantee total containment, operational stability, and maximum longterm reliability — essential requirements for any industrialgrade sodium hypochlorite pump.
Industrial, chemical, and pharmaceutical uses of hypochlorite
Sodium hypochlorite is used across multiple sectors, from water treatment to industrial sanitation. Below are the main applications and related operational requirements.
- Drinking and wastewater treatment: controlled NaClO dosing is used for water disinfection and biofilm control in cooling circuits; pumps must ensure precise dosing, on/off cycles, and compatibility with chlorates and salts.
- Production of detergents and sanitising agents: used as a raw material or oxidising reagent; pumps must prevent contamination and preserve solution purity.
- Healthcare and pharmaceutical sectors: diluted solutions for surface and instrument sanitisation; pumps must often allow CIP (cleaninplace) washing and fast decontamination procedures.
- Specific industrial applications: microbiological control in food plants, coolingwater treatment, controlled oxidation processes in chemical plants; each application requires specific materials and certifications.
Critical issues in pumping sodium hypochlorite
Pumping sodium hypochlorite presents phenomena that, if not properly addressed, compromise plant safety and efficiency, and pose risks to both the environment and operators.
Main technical issues include:
- Metal corrosion and localised reactions: hypochlorite attacks many ironbased alloys and can accelerate stress corrosion cracking, causing rapid material loss and possible fluid contamination.
- Instability and chlorine formation: temperature increases or pH reduction promote chlorine release, increasing exposure risks and corrosion of unprotected components.
- Mechanical seals as a weak point: traditional seals wear quickly, leading to leaks and frequent replacements; they also represent a potential contamination pathway.
- Byproducts and environmental impacts: reactions with organic compounds can generate persistent chlorinated substances; a proper pumping system design minimises formation and dispersion.
Why choose fluoroplastic materials: ETFE and PP
To counter these issues, materials offering complete chemical resistance are required. Fluoropolymers (such as ETFE) provide excellent resistance to oxidation and strong bases found in industrial hypochlorite solutions.
ETFE, in particular, combines chemical resistance with mechanical rigidity.
PP is used in milder applications, but for higher concentrations and temperatures, fluoropolymers remain the preferred choice.
A metallic outer casing internally lined with ETFE or PP (the lined approach) offers the ideal balance between mechanical strength and chemical compatibility.
CDR’s ETN EVO pump: description and construction features
The ETN EVO is a singlestage centrifugal magneticdrive pump designed specifically for transferring chemically aggressive fluids such as sodium hypochlorite.
Its lined construction features a ductile iron external casing for mechanical strength and ease of installation, while the inner lining in chemically resistant plastics such as ETFE or PP fully protects all wetted parts. This combination ensures structural solidity and chemical durability, drastically reducing corrosion.
Motion transmission occurs through magnetic coupling, eliminating the need for traditional mechanical seals.
The magnetic assembly — using highperformance permanent magnets protected by a technicalmaterial containment shell — ensures stable and safe operation even under load fluctuations.
The ETN EVO complies with the SubISO 2858 standard, simplifying integration or replacement in existing plants without major structural changes.
Available in multiple sizes and configurations, the pump covers a wide range of flow rates and heads, and is designed for reliable operation even in discontinuous service. The internal design improves venting and correct filling of the pump chamber, enhancing overall reliability and service life.
Maintenance, reliability, and economic impact
From a maintenance perspective, the absence of mechanical seals in the ETN EVO eliminates a major source of downtime, while the internal lining protects surfaces from degradation.
The initial investment must be assessed in terms of fewer interventions, reduced sparepart consumption, and lower environmental risks — translating into a tangible economic return, especially in continuousdosing systems or highsafety applications.
Additionally, CDR Pompe supports customers with scheduled maintenance plans and onsite inspections to maximise product lifespan and operational safety.
For critical applications such as pumping sodium hypochlorite, the combination of the right technology (fluoropolymeric materials, lined design, magnetic drive) and specialised knowhow is essential.
If you need a sodium hypochlorite pump that reduces risks, downtime, and longterm costs, the ETN EVO is a proven solution backed by certified technical data.
Contact the CDR Pompe technical team for a tailored evaluation: process analysis, pump sizing, material selection, and maintenance planning will be adapted to your specific operating conditions.