Double-end face sealed pump

Double-end face seal pump is mainly used in pumping systems that contain hazardous, toxic, or expensive media. The design of double-end face seals can effectively prevent medium leakage, thereby enhancing the safety and environmental friendliness of the equipment. Specifically, it consists of two relatively independent sealing surfaces, which are usually installed at both ends of the pump and enable better control over the isolation between the interior of the pump and the external environment. .

Both Layout 2 and Layout 3 in API682 belong to double-end face mechanical seals, that is, they have two pairs of moving seal faces.

Arrangement of double-end face mechanical seals: In the arrangement that uses double-end face seals, the following aspects need to be taken into consideration: (1) The medium being pumped is a high-risk one, being toxic and harmful; any leakage of such a medium can cause serious harm to human health； (2) The medium pumped is a high-temperature one; therefore, during transportation, once the temperature exceeds the ignition point of the medium, a leak can lead to a risk of fire as well as the possibility of burns ； (3) It can have a significant impact on the environment in the event of a leak. Therefore, when using double-end face mechanical seals, in order to enhance safety, it is necessary to incorporate mechanisms within the equipment that complement this type of seal, so as to ensure a secure sealing effect. This allows the manufacturers of mechanical seals to provide not only the seals themselves but also corresponding flushing solutions. In such flushing solutions, it is important to use equipment with external pressure enhancement to assist in dealing with blockages; the pressure applied here is about 0.1–0.4 MPa higher than the pressure of the medium being sealed. Thus, it is necessary to use high-pressure fluids to overcome these blockages, allowing them to flow into the system where the sealing takes place. In the Plan53 or Plan54 approaches used in this article, some of the blocking fluid ends up mixing with the fluid that is to be sealed. Therefore, when selecting a fluid for use as a blocking fluid, it is necessary to choose one that is cost-effective and will not contaminate the fluid being sealed, in order to avoid any issues during production or transportation. Additionally, in the blocking fluid, circulation is generally achieved through the pump effect ring built into the mechanical seal or via the phenomenon of thermal siphonage; therefore, during installation, an auxiliary system must be used to ensure smooth flow of the blocking fluid. Therefore, when studying flushing schemes for double-end face mechanical seals, it is necessary to use the Plan53 or Plan54 schemes, which provide better flushing, cooling, and lubrication effects. In summary, when using double-end face sealing equipment, mechanical seal products must be provided during delivery, and an appropriate sealing flushing scheme should be selected based on the specific operating conditions. This scheme should be used correctly and appropriately to avoid mechanical damage or other failures that could lead to leaks.

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