The mag-drive pump has long been an important pump design in the heavy chemical and pharmaceutical Industry. In the modern Industrial world, it is becoming more common to move increased volume of chemical and acids around by ship, lorry and in Intermediate Bulk Containers (IBC’s) for use on sites, and so 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 more the re-classification 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 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 of which allows magnetic drive pumps 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.
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 we assess the problems the pumps will face in such an application, it is evident that there are three major potential issues to concern ourselves with, 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 device. 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 advantage of eliminating a big problem area which is eddy currents, with a non metallic shell you simply don’t 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, however, 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, we 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 far superior mechanical strength to withstand hydraulic and mechanical forces. CDR Pumps widely use both the ETN-L series of lined pumps, and ETS series of Stainless steel pumps for such applications.
To find out more about how successful tanker unloading applications are achieved with minimum risk to operators and the environment, call our office on 01933 674777