Pumping Ethanol

Ethanol aka Ethly alcohol is a colourless volatile, flammable fluid with a slight odour. In concentrated, purer form it is toxic with background fumes requiring monitoring for occupational exposure.

As a chemical it is produced via fermentation for biofuel and beverage consumption and by the hydration and distillation of ethylene for industrial applications.

The production of ethyl alcohol involves the uses of agricultural crops, enzymes and yeast solutions, all of which are slurry fluids with a particular demand from pumping solutions. The focus of this sheet is  the end ethly alcohol product which can be thought of a water-type consistency. 

• Ethyl alcohol is predominantly used as a fuel or fuel additive for automotive, spirit and rocket fuel blends
• As a solvent, ethyl alcohol is utilised in cosmetics, flavourings, medicines and even paints and varnishes.
• Proteins and cells can be denatured by ethly alcohol and for this quality it is used in anti-septic treatments and household products
• As an industrial feedstock for organic compounds such as acetic acid and ethyl halides, used in lighting.

As ethanol is a volatile fluid and also toxic, the containment of the fluid should be the first consideration. The prospect of a leak, particularly in a refinery can be exceptionally dangerous and cause costly downtime. Where shaft-sealed pumps are in use it is recommended switching to a mag drive pump.

A mag drive pump does not use mechanical seals, but rather employs an o-ring sealing system. As the pump is driven by a magnet assembly attached to the impeller, yet separated form the drive there is no danger of leakage.

Providing the ethanol is pumped as briefed the pump should work for many years. It is recommended that where mag drive pumps are installed that they are kept in a flooded state to prevent dry-running and even cavitation.

Ethanol has a higher vapour pressure than water and attention should be given to the suction and discharge ports to prevent any dangers from cavitation from lower NSPHr.

Depending on the filtering of the ethanol, a fine micron filter should be applied as many mag drive pumps can not handle any degree of solids or build-up e.g. 150 microns and above. Where particulates are unavoidable or in a high concentration, thrust-balancing mag drive pumps can be used to handle small solids. The pump prevents small solids accessing the containment tube which can get clogged. The solids are instead sent straight through the impeller and out of the discharge. The solids handling capability is up to 3mm with softer particles only being passed. Any type of harder, abrasive particles 

Most metals are acceptable with the avoidance of aluminium, brass and zinc alloys. Contaminants in the ethanol can cause an increase in corrosiveness, however most stainless steel alloys are excellent. 

PTFE and Kalrez elastomers are preferable with lower grade quality materials being reported as ‘swelling’ and degrading. Where higher temperatures are in use it is certainly recommended to use PTFE and at lower temperatures Viton is acceptable.

Many ethanol pumps are installed in ATEX rated areas so a conforming specification and leak-free performance is a priority.

For smaller transfer and container applications, an AODD air diaphragm pump can be used, particularly in ATEX areas as compressed air is used to power the pump.

AODD pumps can handle smaller solids and run-dry for short periods, making it ideal for transferring ethanol from containers.

The range of materials available also makes it exceptionally versatile for use in hazardous areas.