Special benefits for liquified gas applications

Featured Product from Dickow Pump Company, Inc.

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Multistage Centrifugal Pumps Type HZSM/HZSMA

General
Magnetic coupled DICKOW-Pumps of series HZSM / HZSMA are of sealless design. The containment shell forms a closed system with hermetically sealed liquid end. The properties of the integrated side channel stage allows the handling of entrained gas and operation under suction lift conditions.

Applications
Magnetic driven HZSM / HZSMA-pumps are designed to improve plant and personnel safety, especially when handling toxic, explosive or other dangerous liquids which react on contact with the atmosphere. For all these services the containment shell replaces double acting mechanical seals, along with external fluid reservoirs and the necessary control equipment. HZSM / HZSMA-pumps therefore offer exceptional benefits to the chemical, petrochemical and allied industries and fulfill all environment protection rules. Due to the fact that 90% o pump failures are caused by leaking shaft seals, the sealless design increases the availability and reduces maintenance costs. The HZSM-type is used in tank farms, for offloading rail cars and trucks, filling of storage tanks and other applications where priming of empty suction pipes is required. Considering low NPSH-values, gas handling capability and sealless design, the HZSMA-type offers special benefits to liquified gas applications. Typical application is filling of LPG-trucks and rail cars in refineries.

Why Sealless?

Why Use Dickow Magnet Drive Pumps?

Since the 1970s concern for the environment has become increasingly important in the design of industrial plants. Today this issue is a vital concern in any discussion involving new plants and updating of facilities. Equipment designers, engineers, and suppliers must offer solutions which will eliminate any adverse environmental impact, or at a minimum reduce it to sustainable or regulated levels.

The weakest link with respect to centrifugal pumps is the shaft seal, when considering release of fluids to the environment. This is because there is always some inherent emissions from mechanical seals. The average emission rate of a mechanical seal is 0.13 GPM to 0.35 GPM, and although this appears to be quite small, the actual atmospheric penetration is quite large when one considers that large chemical plants have thousands of pumps in operation. In 1989 the Environmental Protection Agency (EPA) published its first report on environmental pollution. The report documents that American chemical and petrochemical industries, in 1987, emitted 390 tons of toxic materials into the atmosphere, in part attributable to pump leakage.

Potential problems occur by the formation of dangerous explosive mixtures, which become worse when toxic or malodorous gasses and vapors endanger plant personnel. In order to prevent the vaporization of liquids between seal faces additional cooling is required when the media has vapor pressure greater than atmospheric pressure at operating temperatures. Additionally, when handling fluids that crystallize in the atmosphere, an appropriate quench connection or barrier fluid must be provided.

Various attempts have been made to improve the performance of mechanical seals in order to meet regulations pertaining to emissions. Examples include double acting mechanical seals of "tandem design", "back-to-back design", and various gas seal types. All of these require auxiliary equipment, systems, and controls. For many applications the costs of this equipment is not justifiable in light of the gains attained.

It would appear that the outer limits have been reached for improvements in mechanical seals with regard to reliability and emissions control. The only realistic solution is a sealless pump with zero leakage, i.e. without the connection of the media to the environment due to the absence of a seal. Many of our earliest customers installed Dickow sealless magnet drive pumps for their zero leakage feature, but quickly realized that their mean times between failures was greatly improved as down time due to seal replacement was eliminated completely.

Dickow Pump Company has produced pumps for over 100 years. Our pumps are working steadily and dependably in all corners of the globe.

As the technical world leader in magnetic drive pumps, Dickow holds many patents, is ISO 9001 certified, and is a supplier-partner of major chemical companies.