Corrosion Inhibition

Instructions for using sodium silicate and sodium sulfite to prevent corrosion in thermal storage systems.

Sodium silicate (corrosion inhibitor)

Sodium silicate forms a thin, protective silica film on metal surfaces such as copper, brass, and steel. This reduces maintenance costs by minimising corrosion-related damage.

Dosage: 400 grams per cubic metre of water.

Sodium sulfite (oxygen scavenger)

Sodium sulfite chemically reacts with dissolved oxygen in the water, eliminating it and thus reducing corrosion risk. This is particularly important where air ingress occurs.

Dosage: 30 grams per cubic metre of water.

Application process

1. Safety preparation — wear protective equipment (gloves, eye protection)
2. Dissolve and add chemicals to the thermal store
3. Circulate — run pumps for a minimum of 1 hour per cubic metre for thorough mixing
4. Monitor pH levels (target 9.0-10.5) and sulfite concentration (target 20-40 mg/L)
5. Top up chemicals when water is added or levels drop

Maintenance

Test every three months:

• pH level (maintain 9.0-10.5)
• Sulfite concentration (maintain 20-40 mg/L)
• Visual inspection for corrosion
• Water clarity

Additional considerations

• Minimise air ingress to reduce oxygen scavenger consumption
• Use softened or demineralised water where possible
• Store chemicals in cool, dry conditions away from direct sunlight
• Both chemicals are registered under the REACH Regulation (EC) No 1907/2006