German NILOS seals NILOS models NILOS prices

NILOS seals refer to devices that prevent fluid leakage, formed by at least one pair of end faces perpendicular to the axis of rotation maintaining contact and sliding relative to each other under the action of fluid pressure and the elastic force (or magnetic force) of the compensation mechanism, in conjunction with auxiliary seals. When the auxiliary seal of the compensation ring is a metal bellows, it is called a bellows mechanical seal. There are mainly the following four types of components. a. Primary sealing elements: rotating ring and stationary ring. b. Auxiliary sealing elements: O-rings. c. Clamping elements: springs, thrust rings. d. Drive elements: spring seats and keys or fixing screws.

NILOS seal classification

1) Packing seal; the packing seal has a simple structure, low price, and convenient maintenance. However, it has high leakage volume and high 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, and toxic media. 2) Mechanical seal: mechanical seals (also known as face seals) provide good sealing performance, very low leakage, and long service life, but they are expensive, and their processing, installation, maintenance, and repair requirements are higher than those of general seals. Mechanical seals are suitable for transporting petroleum and chemical media and can be used for media with various viscosities, strong corrosiveness, and containing particles. The American Petroleum Institute standard API610 (8rd edition) stipulates: unless otherwise specified by the user, cartridge mechanical seals shall be installed. 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 medium pressure at the shaft seal to atmospheric or negative pressure, preventing leakage during use. When stopped, 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 sealing effect. Packing seals are commonly used in shutdown sealing devices paired with back-vane (or auxiliary impeller) seals. Packing seals come in two types: 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 price, and convenient 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 greater power loss compared to mechanical seals and shorter service life of the shutdown sealing device. The seal between the rotating pump shaft and the fixed pump casing is called the shaft seal. Its function is to prevent high-pressure liquid from leaking out along the shaft from inside the pump, 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, it can be divided into contact dynamic seals and non-contact dynamic seals. In contact dynamic seals, the sealing device contacts the shaft, resulting in relative friction between the two. Contact dynamic seals include packing seals and mechanical seals.

NILOS 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 pump operating pressure should be stable, with pressure fluctuations not exceeding 1 kg/cm². 3) During pump operation, avoid cavitation to prevent dry friction of the sealing faces and seal damage. 3) Check the sealing condition frequently. During operation, if leakage exceeds the standard, it should not exceed 5 drops/min for heavy oil and 10 drops/min for light oil. If there is no improvement within 2-3 days, stop the pump to inspect the sealing device.

NILOS seal troubleshooting

1) Main factors causing oil seal leakage: poor sealing of the oil seal is the main cause of leakage. When the shaft wears and forms grooves, even replacing with a new oil seal may not achieve sealing because the contact pressure between the oil seal lip and the shaft decreases, resulting in insufficient interference fit between the oil seal lip diameter and the shaft diameter after installation. Taking the S195 diesel engine crankshaft oil seal as an example, the main reasons for poor sealing are analyzed as follows: (1) poor manufacturing quality of the oil seal; (2) poor quality of the shaft or bearing; (3) improper use and maintenance; (4) improper installation; (5) improper storage, adversely affected by environmental pollution. 2) Countermeasures for leakage due to poor oil seal sealing: acquire basic knowledge to identify counterfeit and inferior products, and purchase high-quality, standard oil seals. During installation, if the outer surface roughness of the shaft diameter is low, or if there are defects such as rust spots, corrosion, or burrs, polish smooth with fine sandpaper or an oil stone; apply clean engine oil or lubricating grease to the oil seal lip or the corresponding position on the shaft diameter. Apply sealant to the outer circle of the oil seal, wrap the keyway area on the shaft with hard paper to avoid scratching the oil seal lip, and use special tools to rotate and press the oil seal inward. Never hammer or force it, to prevent deformation of the oil seal or breaking of the spring, which would cause failure; if the lip turns over, the spring falls off, or the oil seal tilts, it must be removed and reinstalled. Note: do not arbitrarily tighten the inner spring when the shaft diameter is not worn and the oil seal spring tension is sufficient. Oil seals used in machinery generally operate under harsh conditions, with large environmental temperature differences, much dust, and frequent vibration causing changing stress conditions on components; therefore, frequent inspection, maintenance, and upkeep are required. If the shaft diameter and bearing are severely worn; if the oil seal rubber ages or the spring fails, repair and replace the corresponding parts promptly. Troubleshoot abnormal heating of components or assemblies promptly; avoid overspeeding and overloading the machinery to prevent increased temperature at the oil seal lip, rubber aging, and premature wear of the lip. Frequently check the engine oil level; if there are too many impurities in the engine oil, such as alloy powder or metal iron filings, completely replace with new engine oil. The brand and quality of the replacement engine oil must meet seasonal requirements. It is recommended to add Metral Super Sealant & Lubricant to the engine oil; it is an excellent gearbox additive that forms an inert material film on components, which can reduce oil seal leakage, extend the service life of oil seal gears, and reduce gearbox noise. The use of this Metral super sealant lubricant will not contaminate the oil or cause deterioration.

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