Hong Kong Branch: The value of non-corrosive water pumps
Corrosion of immersed water pumps is a common problem that leads to equipment failure. The CIPHE Hong Kong Branch discusses innovations to prevent damage occurring
When dealing with chemically aggressive and abrasive waste water, it’s important that pumps are made with resilient components. A common problem that occurs when pumping this type of waste water is that the shaft seal and cable inlet are attacked and destroyed by the fluids. This enables the corrosive liquid to enter the motor housing, which can reduce the performance, cause permanent defects or lead to total failure of the pump.
To combat this issue, HOMA Pumpenfabrik GmbH has developed a comprehensive range of stainless steel, submersible pumps. The individual series CH, CTP, MXS, CV, CVX and KX are equipped with discharge connectors from 2-inch to DN 400. The units are made of resistant, investment cast stainless steel, which means vibrations are absorbed more effectively. This results in less stress on the bearing and mechanical seal, which increases its service life and considerably reduces the frequency of maintenance required.
The highly resistant investment cast stainless steel makes the series resilient against aggressive fluids. In addition, contaminated water containing solids, such as sand and sludge, can also be pumped. The pumps can handle fluid with solid size starting from 10mm up to 150mm. Due to its compact and robust design, this stainless steel unit is versatile and can be installed and operated on either a stationary or mobile basis, making it ideal for use in the chemical industry and for the disposal of abrasive waste water.
To ensure continuous pumping, individual components, such as the motor housing, impeller and pump housing, are made of stainless steel 1.4408. The motor shaft is manufactured with stainless steel 1.4462, while the various mechanical connecting parts also use stainless steel 1.4408. The mechanical seal is available as an encapsulated version, so that the spring of the seal does not come into contact with the pumped medium. This eliminates the need for bellows, which tend to be a fragile component. Liquids can be transported at temperatures of up to 40°C and levels of 60°C can also be sustained for brief periods. In addition, the submersible pumps are available in an explosion-proof design, in line with the ATEX Directive II 2G Ex c d IIB T4(T3).
There is an increasingly high demand for using stainless steel submersible pumps in infrastructure projects, such as the Airport Authority (Third Runway project), MTRC (Shatin to Central Link) and some private developers of residential housing in Hong Kong.
Although the initial cost is high compared to cast iron pumps, companies are willing to use the stainless steel submersible pump due to its high corrosion resistance, enhanced service lifetime and trouble-free operation, which results in a reliable pumping system.