Choosing between 20% and 50% sodium hypochlorite (NaClO) rests on three levers: active chlorine per litre (dosing and freight economics), free-alkali buffering (decay rate and storage life) and the clarity/handling of the solution. The critical point: in the KORKİMYA portfolio the '20%' and '50%' in the grade name refer to the light transmittance coefficient, not to chlorine strength. Per the product data, the 20% grade actually carries higher active chlorine (min. 190 g/dm³); the 50% grade has active chlorine of min. 170 g/dm³ but higher free alkali (20-30 g/dm³). So water treatment and bleach producers that prioritise disinfection power per litre usually prefer the 20% grade, while buyers who prioritise a clearer solution and a higher alkali buffer prefer the 50% grade. Both grades sit in the same transport class (UN 1791, packing group III).

What do sodium hypochlorite 20% and 50% actually mean?

Both grades are the same chemical: a greenish-yellow homogeneous aqueous solution with the chemical formula NaClO and CAS number 7681-52-9. The percentage in the grade name is the light transmittance coefficient, not the chlorine content; in other words it is an indicator of the solution's clarity/quality. The parameter that determines disinfection power is a separate specification, the active (available) chlorine content. This distinction matters: although the '50%' name looks higher, in the product data its active chlorine per litre is lower than the 20% grade's. The right grade is chosen by your application's active chlorine, stability and logistics needs, not by the label percentage.

How do active chlorine, decay and storage life differ?

Sodium hypochlorite is a strong oxidiser and loses active chlorine over time under the influence of light, heat and metal ions (especially iron); this is the most critical issue in supply. The free alkali in the solution (expressed as NaOH) acts as a buffer and slows decomposition. Per the product data, the 50% grade has higher free alkali (20-30 g/dm³) whereas the 20% grade has 10-20 g/dm³; in both grades iron is limited to a maximum of 0.02 g/dm³. For shipments held in stock for a long time or stored in warmer conditions, the higher alkali buffer gives more handling margin. Even so, the value that sets the final dose is the current active chlorine at delivery; rotate stock quickly (FIFO) and rely on batch-based analysis values.

İNORGANİK KİMYASALLARSodium Hypochlorite 20%The 20% grade with high active chlorine per litre (min. 190 g/dm³); an easy-to-dose solution for drinking water, pools, textile bleaching and industrial water treatment.

Which grade wins on freight and dosing economics?

Freight and dosing are calculated on active chlorine per litre. Per the product data, the 20% grade has active chlorine of min. 190 g/dm³ and the 50% grade min. 170 g/dm³; that is, to deliver the same total active chlorine you ship slightly fewer litres with the 20% grade, so freight per unit of active chlorine is that much more efficient. Because dosing systems are calibrated to a target active chlorine value, when you switch grades you must update pump/injection settings to the new active chlorine figure. The table below compares the two grades using the product specification values:

PropertySodium Hypochlorite 20%Sodium Hypochlorite 50%
AppearanceGreenish-yellow homogeneous liquidLight yellow to greenish-yellow homogeneous liquid
Light transmittance coefficient (%)min. 20min. 50
Active chlorine concentration (g/dm³)min. 190min. 170
Free alkali / decay buffer (as NaOH, g/dm³)10 - 2020 - 30
Iron concentration, max. (g/dm³)0.020.02
Transport class (UN / packing group)1791 / III1791 / III
Packaging optionsRubber-lined tanks and containersRubber-lined tanks, containers and polyethylene barrels
Dosing economics (active chlorine per litre)Higher (min. 190 g/dm³)Lower (min. 170 g/dm³)

The values in the table are taken from the product specifications. If you target a specific active chlorine range or different packaging for your application, you can share your requirement with our supply team.

İNORGANİK KİMYASALLARSodium Hypochlorite 50%The 50% grade with a higher light transmittance coefficient and higher free alkali (20-30 g/dm³); for bleaching, food facilities and chemical processes, with a polyethylene barrel option.

Which grade for water treatment, sanitation and textiles?

Both grades serve water treatment, sanitation and textile applications; the choice is made by the application's active chlorine and handling needs. The active ingredient of household bleach is also sodium hypochlorite, so producers looking for a bleach raw material use these grades. The leading application areas in the product data are:

  • Disinfection of drinking water networks (registered disinfectant applications).
  • Disinfection and treatment of swimming pool water.
  • Industrial water treatment and sterilisation.
  • Bleaching of fabrics and pulp in the textile and paper industries.
  • Active ingredient in household bleach and general surface/sanitation products.
  • Disinfection of food facilities and equipment.
  • Wastewater and environmental disinfection.

Selection and safe handling

Sodium hypochlorite is a corrosive oxidiser; it causes irritation or burns to skin and eyes. On contact with acids it releases toxic chlorine gas and must never be mixed with acids or organic substances. Always work with chemical-resistant gloves and eye/face protection in a well-ventilated area; store the product away from sunlight in closed, unheated areas in corrosion-resistant containers, and follow the product's current Safety Data Sheet (SDS).

Sodium hypochlorite supply with KORKİMYA

KORKİMYA supplies sodium hypochlorite in 20% and 50% grades to industrial buyers in the water treatment, pool, textile/paper, sanitation and chemical sectors. Each shipment is confirmed against the active chlorine, free alkali and iron values in the product specification; on request, a certificate of analysis (CoA) and a Safety Data Sheet (SDS) are shared. Submit your grade, volume and delivery point through a single form on the product pages, and we respond quickly to your sample and quote request.