MAGNETIC DRIVE SEALLESS PROCESS PUMPS
An possible alternative to mechanically sealled pumps

Ingersoll-Dresser Pumps has announced a new extension to its CPXS range of magnetic drive, sealless chemical process pumps. The number of drives has been increased with the introduction of the new model 150 drive. This extends the maximum drive rating to 45 kW at 2950 rpm with Neodymium magnets and 37 kW at 2950 rpm with Samarium Cobalt magnets. The increased torque has also resulted in the addition of another pump size to the range making 21 in all.

CPXS pumps combine the leading edge technology of the magnetic drive system with well-proven, state-of-the-art hydraulic designs from the CPX chemical process pump range to ensure high efficiency and low NPSH performance. The 21 sealless magnetic drive pumps in the CPXS range cover capacities up to 300 m³/h and heads up to 100m.

For process applications
CPXS pumps are used where a liquid being pumped is hazardous, toxic, flammable, explosive or simply valuable and the possibility of emissions or leakage owing to mechanical seal failure is unacceptable. The risk of leakage is removed by replacing the mechanical seal with a static containment shell to create a closed, leak-free system. The range can offer further assurance with the option of a secondary containment system comprising two static shells each providing 100% fluid containment. In addition, the company can carry out sophisticated analysis of flow, pressure and temperature at several locations within the pump using Flow Path Analysis Software. This can provide increased user confidence when specifying for critical applications.

condition monitoring option
For the ultimate in pump protection, it is also possible to install optional condition monitoring connections. As standard, the discharge to discharge circulation of the pumps eliminates flashing in the drive and an optional external flush arrangement improves solids handling and reduces maintenance costs. Tolerance rings provide optimum bearing bush alignment and retention and the use of graphite-filled silicon carbide, an advanced material, for the bearings, provides short term dry running protection. An also optional safety skid ring protects the containment shells from damage in the event of bearing failure.
Another of the many reasons for user confidence in the design of the new pump is the chrome oxide coated shaft which eliminates differential expansion problems at high temperatures. Where the customer prefers a sleeved shaft instead of the coated shaft, this is also an option.

not for all applications
According to the company, pumps with shaft seals normally exhibit minute leakage, either of the pumped liquid with single seals or barrier fluid with double seals. Seal manufacturers claim zero leakage with some designs but system upset conditions can still result in fugitive emissions and there is always the possibility of seal failure.
It should be noted that a magnetic drive is not the solution for all applications, says Ingersoll-Dresser Pumps. High temperature liquids, those with a high concentration of solids, those containing magnetic particles or liquids with a tendency to polymerise, all pose potential difficulties for magnetic drives. Ingersoll-Dresser Pumps says these difficulties can often be resolved but for some applications a mechanical seal system may well be the best solution.

twisted vane design
CPXS pumps form part of the CPX family of chemical process pumps. The CPXS design incorporates some of the best of the well-proven features of the CPX pump with a number of specific aspects for very energy-efficient, trouble-free operation and low maintenance costs. CPXS pumps therefore feature the same open impeller concept of the CPX range, providing excellent solids handling performance and reduced maintenance costs.
The twisted vane design of the impeller is very efficient and lowers the energy requirement for the pump. The ability to adjust the clearance on the impeller also maintains the high efficiency and low running costs of the pumps.

material options
The large number of material options for the new pump range ensures compatibility with a wide range of liquids for long-life performance.
Materials available include Ductile Iron, 316L Stainless Steel, 304L Stainless Steel, Duplex Stainless Steel, Carbon Steel and a selection of Alloys including Alloy C-276. A 3 mm corrosion allowance is standard on all casings.
The operating life of the pumps is further extended by the optimised internal flow path to lubricate bearings and cool the metal shell if fitted. Inner and outer rotors in the pump are dynamically balanced as standard, reducing vibration and contributing to the extended life performance.