Tanker unloading applications

The mag-drive pump has long been an important pump design in the heavy chemical and pharmaceutical industry, finding its way into some of the most arduous applications, and proving to offer extended operating life, as well as zero emission into the atmosphere of toxic, corrosive or explosive liquor or vapour.

In the modern industrial world, it is becoming more common to move increased volume of chemical and site acids around by ship, lorry and in Intermediate Bulk Containers (IBC’s), and because of this the chemical distribution market has seen massive growth and investment to utilise ‘best practice’ to ensure the safe and efficient handling of toxic and corrosive liquids.

Continued government legislation and the reclass-ification of liquids under the ADR and IMDG regulations, means that industry is ‘preferring’ to unload road tankers by means of pumped discharge, as opposed to ‘blowing’. The ‘blowing method is achieved by pressurising the supply vessel, and the differential pressure results in emptying of the tran- sport tank to storage tank. With this however come a number of design and safety issues to address.

Changing pump design and technology, as well as  advancement in materials of construction, has evolved in recent years to make sure that this potentially troublesome application is safe and efficient. With the development of CDR Pumps RunSafe bearing’s, a technology which allows magnetic drive pumps to safely run dry for periods of time along with materials of construction, has allowed Magnetic drive pumps to safely and reliably be used on these applications. This method of tanker unloading is also proving to be a cheaper option for customers, as fume cleaning devices are not required as vapour can be safely returned to the tanker, thus eliminating the need for costly fume scrubbers.

The trend is leaning toward lined pump units, whether that be Polypropylene for general chemicals, or indeed ETFE for solvent based liquids and other more corrosive products, both available on the CDR Pumps type ETN-L and UTN-BL pumps. When CDR Pumps assess the problems the pumps will face in such an application, it is evident that there are three major potential issues of concern; priming of the pump prior to start up, dry-running of the pump unit when the tanker becomes empty, and nozzle loads and forces.

The issue of priming is simply a case of installation, plant layout and operational procedure to ensure that once the tanker is connected, the system can be effectively primed up to the pump impeller and suitably vented to fume scrubber or other vapour cleaning devices. If installation is to prove troublesome, then CDR Pumps can also offer magnetic drive self priming pumps for such applications.

The dry running issue has a number of points to consider, with non-metallic pumps comes the advanantage of eliminating a big problem area which is eddy currents, with a non metallic shell you simply do not generate heat in the product – eddy currents are an effect of passing moving magnetic forces through a stationery static metal component, in the case of a pump, the magnets rotate around a static isolation shell.

With modern bearing material coupled with impeller and magnetic coupling design, dry running of magnetic drive pumps can be readily achieved, how- ever, this is still not best practice, as the pump will be suffering excessive wear on the bearings, so with the use of a modern pump protection device, with CDR Pumps you can control the pump to automatically stop once the tanker becomes empty.

The general trend is to use flexible pipework from the road tanker to the pump, often by cam-lock style fittings. With the regular movement of pipework as tankers arrive and depart, the robustness of a lined pump is favourable, as these provide a far superior mechanical strength to withstand hydraulic and mechanical forces. CDR Pumps widely use both the EETN-L series of lined pumps, and ETS series of stainless steel pumps for such applications.

Successful tanker unloading applications are achieved by ensuring some key practices are implemented, once installed correctly, you can be assssured of long operational life of your plant, with minimum risk to operarators and the environment, and CDR Pumps will prove to be a reliable cost effective partner to ensure your plant remains operational at all times.

Contact CDR Pumps for more information on 01933 674777
or visit www.cdrpumps.co.uk