The GMN gap seals are made of two plastic rings. They are creating a radially, increasing labyrinth gap.
The labyrinth peaks are overlapping each other. With the assembly the rings are simply clicked together.
POM-H
POM-C
Temperature range: -40° to +60° C
Specials with O-rings from -40° to +80° C
The acetal resin our seals are made of is resistant against a large variety of chemicals such as: the most of the common organic solvents, alcohols, esters, ketones, aliphatic and aromatic hydrocarbons, greases and oils. Alkaloid water and base even at higher temperature do not harm the material. Another advantage of this material is the very low value of water pickup (max. 0.8%).
On the other hand this material may not be used to seal against oxidants and organic and inorganic acids (pH < 4).
Please choose the first letter of the chemical and then the requested type.
The basic principle of a labyrinth seal is based on the geometric shape of the labyrinth which causes some turns of the contaminant on its way to penetrate the seal. With the GMN gap seal the efficiency of the centrifugal force to accelerate the contaminant radial to throw it away from the sealing gap is increased by the conic envelope of the labyrinth. To penetrate the seal the contaminant has to overcome the centrifugal force by creeping from the larger labyrinth diameter facing the contaminant to the smaller diameter on the "dry" side of the seal. Particles penetrating the first steps of the conic labyrinth are expelled by the centrifugal force and led back to the side of the seal facing the contaminant.
The most important aspects are
There is no chance for a gap seal to protect against higher liquid levels and a pressure gradient between inside and outside of a non-contact seal. Pressure gradients may be reduced or throttled but not sealed.
The right mounting direction:
Please note, that the larger labyrinth diameter faces the contaminant.
For this type of requirement the gap seal may be filled with grease before the mounting to increase the sealing efficiency against dusty environment. Please mark your order "pre-greased". A certain amount of the grease may be moved out of the seal at rotating shaft. Available for type "S" only.
Please note the indication with your order: S d x D x B greased.
Axial and radial clearances of the seal are almost the same - approximately 0.5 mm - 0.8 mm. They affect each other.
GMN gap seals are pressed onto the shaft with a certain press fit. Due to centrifugal forces the inner ring could lift off of the shaft because of its own mass. The diagram below shows the speed limit depending on the size.
The exact values can be found in the data sheets.
| Problem: | The contaminant is splashing directly into the sealing gap |
| Solution: | One should use a disc in front of the seal with enough space between the seal and the disc to avoid backup of liquids in front of the sealing gap. |
| Problem: | Heavy splashing liquids |
| Solution: |
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| Problem: | Dual sealing function required |
| Solution: | To keep the contaminant out of and the lubricant inside of the unit one may use two seals back to back (smaller labyrinth diameters of both seals facing each other). You should use a distance ring of at least 0.5 mm in between the seals. If heavy splashing liquids are expected, one may prepare drain hole located between both outer rings; in this case a minimum distance of 3 mm between both seals should be used. |
without any additional device our Non-Contact Seals are providing Ingress Protection (IP) category IP44 according to DIN EN 60 529 (IEC 60 529).
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