German alfalaval seals alfalaval models alfalaval prices

alfalaval seals are a type of friction seal or stuffing box used to prevent liquid leakage between the shaft and bearing of compressors or other fluid handling equipment, and are also sealing devices installed to prevent leakage at the pump shaft and housing. Common types of shaft seals include packing seals, mechanical seals, and dynamic seals. The shaft seal of a reciprocating pump is usually a packing seal. When transporting media where leakage is not permitted, diaphragm reciprocating pumps can be used. The shaft seals of rotary pumps (including vane pumps, rotor pumps, etc.) mainly consist of packing seals, mechanical seals, and dynamic seals.

alfalaval seal classification

1) Packing seal: The packing seal has a simple structure, low price, and is easy to maintain. However, it has high leakage volume and significant power loss. Therefore, packing seals are used for transporting general media, such as water; they are generally not suitable for petroleum and chemical media, especially valuable, flammable, explosive, or toxic media. 2) Mechanical seal: Mechanical seals (also known as face seals) provide good sealing performance with very low leakage and long service life, but they are expensive and require higher standards for machining, installation, maintenance, and repair compared to general seals. Mechanical seals are suitable for transporting petroleum and chemical media and can be used with media of various viscosities, strong corrosivity, and containing particles. The American Petroleum Institute standard API610 (8rd edition) stipulates that cartridge mechanical seals shall be equipped unless otherwise specified by the user. 3) Dynamic seal: Dynamic seals can be divided into back-vane seals and auxiliary impeller seals. During pump operation, the centrifugal force of the back vanes (or auxiliary impeller) reduces the pressure of the medium at the shaft seal to atmospheric or negative pressure, preventing leakage during use. When the pump stops, the centrifugal force disappears, and the sealing effect of the back vanes (or auxiliary impeller) fails; at this time, the shutdown sealing device provides the seal. Packing seals are commonly used in shutdown sealing devices paired with back-vane (or auxiliary impeller) systems. There are two types of packing seals: standard and mechanically adjustable. Standard packing seals are similar to those in general packing seal pumps, requiring slight positive pressure at the shaft seal to avoid dry friction of the packing. Mechanically adjustable packing seals use counterweights to loosen the packing during pump operation and tighten it when stopped. Dynamic seals offer reliable performance, low cost, and easy maintenance, making them suitable for transporting media with many solid particles, such as slurry pumps and feed slurry pumps in the phosphate industry. The disadvantages are higher power loss compared to mechanical seals and shorter service life of the shutdown sealing device. The seal between the rotating pump shaft and the stationary pump housing is called a shaft seal. Its function is to prevent high-pressure liquid from leaking out along the shaft or outside air from entering along the shaft. For centrifugal pumps, the shaft seal is a type of dynamic seal. Depending on whether the sealing surfaces are in contact, dynamic seals can be classified as contact and non-contact dynamic seals. Contact dynamic seals involve contact between the sealing device and the shaft, resulting in relative friction. Contact dynamic seals include packing seals and mechanical seals.

alfalaval seal operation

1) If slight leakage occurs after the pump starts, observe for a period of time. If the leakage does not decrease after continuous operation for 4 hours, stop the pump for inspection. 2) The operating pressure of the pump should be stable, with pressure fluctuations not exceeding 1 kg/cm². 3) During operation, avoid cavitation to prevent dry friction and damage to the sealing surfaces. 3) Regularly check the sealing condition. During operation, if leakage exceeds the standard (no more than 5 drops/min for heavy oil, no more than 10 drops/min for light oil), and there is no improvement within 2-3 days, stop the pump to inspect the sealing device.

alfalaval seal failure causes

Mechanical seal failures are generally identified only after phenomena such as abnormal leakage, abnormal wear, or abnormal torque occur. The causes of failure can be broadly categorized into four aspects: 1) Incorrect design or selection of the mechanical seal; 2) Poor quality of the mechanical seal; 3) The precision of the machine using or installing the mechanical seal does not meet requirements; 4) Incorrect machine operation.

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