Pumping Chromic Acid

Chromic acid is a strong acid, usually consisting of a dichromate dissolved in sulphuric acid.

The acid is a very powerful oxidizing agent and is predominantly used in industry, but also in laboratory settings. Although not flammable or volatile in itself, the reaction with other materials can be potentially hazardous.

Although declining in use worldwide, Chromic acid is still used in many premises. This is due to the toxic nature and new chemical and technological solutions for plating of metals.


Most chromic acid solutions are used in the metals plating industry where the acid itself acts as an intermediary for the application of the thin chrome layer.

Delivering a distinctive colouring to brass, chromic acid was used in restoration treatment of dull musical instruments. Chromic acid is also used in ceramic glazes and lacquer and wood preservatives.

Due to its powerful oxidizing nature, chromic acid is employed in the producton of circuit board and electronic components manufacture. Other chemcial solutions are often sought, such as sulphuric acid-based fluids, due to the highly toxic nature of Chromic solutions.

Pumping considerations

The key consideration for chromic acid is the highly poisonous and corrosive nature of the chemical. As a strong carcinogen it si recommended that there is zero exposure to employees and the environment. Chromic acid may also be hazardous when reacting with reducing agents.

It is recommended that a leak-free pumping solution be used, such as a mag drive centrifugal pump. The pump is made ‘leak-free’ by the separation of the motor drive and the pumping mechanism itself through the use of a magnet assembly. This negates the requirmeent for mechanical seals which are subject to abrasive wear and instead uses an o-ring assembly to seal the casing pieces which prevent any escape to atmosphere.

This seal arrangement also has additional benefits in that the servicing and spare parts cost reduces as the installation and periodic maintenance takes less labour time and over the life cycle of the pump will be dramatically less.

Many mag drive pumps are available in compatible materials such as SS 316 and PP for low 5% concentrations and ETFE/PTFE for higher 50% concentrations.

Where chromic acid is used in metals treatment and contains highly abrasive particulates, a thrust-balancing mag drive pump can be employed. This technology allows the passage of solids up to 3.2mm (not including iron-based magentic compounds). Where the fluid requires circulation such as a plating bath, a vertical centrifugal pump can be employed. Available in chemically compatible PVDF, the pump not only handle the flow and abrasive particles but also the temperatures that many processes require.

Where the fluid is being handled in a small system such as a packaged treatment cabinet, smaller mag drive pumps are available to provide the secure pumping process with the efficiency and compact-size required for installation within a confined space.

Where fitted with a barrier system or equivalent to protect against a failed diaphragm, an AODD pump can provide an excellent pumping solution for basic transfer from an IBC or container, especially in ATEX rated zones where hazardous fluids are in use.

Verder UK supply pumps for virtually every chemical type and application. The Verder range includes leak-free mag drive pumps, chemically inert non-metallic AODD pumps, peristaltic dosing pumps for the accurate delivery of chemical including abrasive and solid-laden types.