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An example of success using a cascade pump for volatile liquids

Petrochemical plantHigh pressure resistantCavitationSpace saving


Pump installed MSW
Cascade stainless steel magnet drive pump

Cascade stainless steel magnet drive pump MSW

The Model MSW cascade magnet pump made by Sanwa Hydrotech is highly rated by company D, North Carolina, one of the largest petrochemical companies in the USA, as it solved their cavitation problem for transferring volatile liquid (fluorocarbon).
(This section contains a description of the pump from a magazine specializing in pumps, the World Pump.)


An engineer Mr. K of company D had been worried as he could not find a pump with a specific special function. He needed a pump that met two requirements. One of them is that the pump must be able to circulate highly volatile fluorocarbons after it is installed at the bottom of a distillation column. The other requirement of the pump was that it must be able to feed the final liquid product without cavitation. The system requires that the pump always operate below 2ft NPSH while the liquid pressure is raised to 100 psi (6.9 bar). In addition, they requested that the pump be able to operate at a very small flow rate 2 to 3 gal/min (0.45 to 0.68 m3/Hr).

They tried various pumps. But they could not find what they were looking for. A canned motor pump does not have enough cooling efficiency, so a pot to add pressure is required and the feed distance had to be extended for this pot." Mr. K said. He also tried a diaphragm pump, and found it had constant liquid leaks and a large variation in the discharge flow rate.

"Lastly, Mechanical engineer Mr. T of company D proposed using a cascade pump, made by Sanwa Hydrotech, in their facility F." Mr. K said. "The MSW pump was equipped with various features and advantages that made it suitable for this specification."

Photographs of MSW model products

The cascade pump MSW by Sanwa Hydrotech has a rapid, sloped flow rate - pressure curve. It can restrict the variation in the flow rate caused by pressure variation in the system. Due to its fluid design, the MSW pump's impeller has a different action than a conventional impeller for feeding liquid at a low discharge pressure. Also different from other centrifugal pumps, the MSW pump can feed highly volatile liquid without causing cavitation.

This pump employs a sealless magnet drive so that it does not leak liquid at all. If expensive mechanical seals are used with conventional pumps for handling high temperature liquid, trouble is likely to occur. The permanent magnet is made of rare earth Neodymium which allows synchronized rotation without slippage. Furthermore, it does not generate much heat. Restricting the generation of heat is very important for the liquid to be fed by the motor. The temperature of fluorocarbon liquid in the distilling tower is always 100C or more.(By not allowing more heat to enter the system, the hazard of forming a liquid vapor can be prevented.)

Mr. T knew about a cascade pump made by Sanwa Hydrotech by Fluid Solution Inc., a local Carolina sales agent for Magnatex. Approximately one year before, he installed the first MSW pump in his factory. Parts contacting the liquid are made of SUS316. It is equipped with a totally enclosed forced fan, electric flange 1.5 HP motor. And it has NPT threads. Since then, there has been no problem.

"The trouble-free operation by the sealless magnet drive system, impeller shape, and specific performances of the MSW pump far exceeded our expectation." Mr. K said. Then they decided to order five additional MSW pumps with the same specifications for the facility.

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