Hydrogen peroxide is a colourless liquid and is commonly used for its bleaching and disinfectant properties.
It is a strong oxidizer and it’s uses range from simple dilute cleaning through to rocket fuels. The chemical itself is non-flammable but is combustible.
The S.G. of the chemical ranges from 1 -1.45. Hydrogen peroxide is available at 3-6% concentration over the counter for household and simple first aid use, 30% concentration for laboratory applications and 68%+ for industrial processes.
- 60% of hydrogen peroxide chemical goes in to the paper industry as part of the pulping process where it bleaches the pulp.
- Hydrogen peroxide is also used for its bleaching properties in the production of flour, hair colouring and teeth whitening cosmetics.
- For basic disinfectant use, hydrogen peroxide is available in low concentration with the benefit that the chemical will degrade to simple water and oxygen.
- In the manufacture of washing powder, hydrogen peroxide is used in the production of sodium percarbonate and sodium perborate.
- As part of odour control in wastewater treatment, hydrogen peroxide is particularly effective in treating aromatic fluids and halogenated compounds.
- For its strong oxidizing nature, hydrogen peroxide is used in rocket propellants where a high concentration solution is released and reacted with a catalyst to cause an exothermic reaction which results in thrust.
Key to the successful pumping of hydrogen peroxide is the selection of appropriate materials and managing the dangers of the chemical ‘gassing off’ causing vapour lock or a potential explosion.
The decomposition of hydrogen peroxide is an exothermic reaction, where the chemical breaks into its constituent parts of water and oxygen. The energy and gas released in this reaction can cause a significant rise in temperature and pressure build up due to the gas volume. This can cause a vapour lock in the system and worse, an explosion and failure of pipe work or fittings.
Common reasons for the cause of off-gassing include the hydrogen peroxide reacting with wet-side materials such as cast iron and nickel.
Should hydrogen peroxide be discharged against a closed valve in the system causing a water hammer shock, the fluid can become unstable and start to decompose.
It is strongly recommended that venting is placed throughout the system.
Compatible elastomers include PTFE, Viton and Kalrez.
A centrifugal mag drive pump is recommended for this application due to the containment properties. A mag drive pump has no mechanical seals which can leak and potential cause a catastrophic incident should hydrogen peroxide be released into the environment. Using an o-ring sealing assembly with no wearable parts between the fluid and the atmosphere the pump will be leak free, providing the fluid is as stated. The wet-side materials may include stainless steel 316, titanium, Hastelloy where the casing is all metal or ETFE/PTFE or Kynar-lined cast iron casing. It is critical that the lining is intact with no permeability through to the iron.
As the working principle relies on flooded suction, it is important to prevent a vapour lock which would cause the pump to effectively run dry as the bearing assembly would fail very quickly.
An AODD pump is also acceptable to use, however it is important to use barrier precautions and leak detection due to the diaphragms being a wearable part. The range of wet-side materials and construction make an AODD pump a very flexible solution.