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Pumping Phenol

Phenol, or carbolic acid is a chemical commonly used a precursor to many well-known materials. It is a widely used chemical, principally as it is inexpensive and abundantly available. 

It is crystalline at ambient temperatures and is flowable/melts above 41oc. As a chemical it is mildly acidic and highly toxic, miscible in water, with a greater capacity to be soluble at higher temperatures. 

Exposure to Phenol vapours or directly onto the skin is highly poisonous with as little as 1g in the bloodstream causing death and can cause chemical burns.

Applications

  • Phenol is primarily used as a precursor in the production of plastics such as polycarbonate, Bakelite, Nylon, epoxy and herbicides.
  • Pharmaceuticals - most notably aspirin, surgical treatments and cosmetics
  • As paint stripper, notably in the aviation 
  • Oil and lubricant blends

Pumping considerations

The crucial aspects of pumping Phenol and related compounds are the levels of toxicity and the chemical resistance of the materials.

Phenol is highly toxic - Although it is only mildly acidic it is extremely poisonous and will cause chemical burns and attack the central nervous system. Inhalation of Phenol vapour can cause irritation to the eyes, skin, respiratory system and internal organs.

It is strongly recommended to transfer phenol and related compounds using a mag drive centrifugal pump as this will ensure absolute containment of the fluid from the working environment. 

A mag drive pump does not have mechanical seals as the power is transferred via magnetic force from a spinning outer magnet to an inner magnet, removing the need for a shaft seal. Where there are shaft seals, there is abrasive wear at the point of containment. As the wear increases and the tolerance increases there is the inherent problem of leaking.

By contrast, a mag drive pump uses an o-ring assembly so there is no mechanism operating between the fluid and the atmosphere and will keep any fluid contained providing the elastomers and construction is compatible with the fluid in terms of temperature, chemical resistance and pressure.

Phenol is compatible with most stainless steel pumps as well as Hastelloy and Titanium. Carbon steel and aluminium may also be compatible at lower temperatures, however these will react with Phenol at higher temperatures. Viton, Kalrez and PTFE elastomers are compatible.

An AODD pump may be used, particularly for IBC and container transfer and where small solids are present. It is recommended to install the pump with either a fluid barrier protection system which detects  when a diaphragm has ruptured and can send an electronic signal to either raise an alert or terminate the air supply. An alternative to this may be a spill-pot attachment with float device. 

As Phenol is a solid until approximately 41oc. Many pumps handling Phenol require a heating jacket to maintain a stable temperature, particularly if the pump is stopped and is not flushed, which may cause the fluid to crystallize. Should the fluid not return to a flowable state on start-up the pump may incur damage.

Phenol may be dosed in some processes such as pharmaceutical production. A cased peristaltic pump allows the accurate delivery of Phenol and the containment of the chemical should a hose rupture. The casing will contain the fluid and it is recommended leak detection is installed.