Graphite loaded PTFE mechanical seals for rotating shafts
A mechanical seal surrounding a rotary shaft to prevent a fluid (i.e., a liquid or gas) from flowing across the seal, the seal including a rotatable seal ring that includes a rotatable seal face, where the rotatable seal ring is rotatable around a rotational axis of the rotary shaft, and a stationary seal ring spatially fixed relative to the rotatable seal ring and having a stationary seal face to engage the rotatable seal face to form the mechanical seal, where the stationary seal ring includes about 1% to about 30%, by weight, graphite, and about 70% to about 98%, by weight, polytetrafluoroethylene. Also, a graphite containing teflon sealing ring used to form a mechanical seal around a rotary shaft, where the teflon sealing ring includes a first seal face capable of engaging a second seal face on a second sealing ring surrounding the rotary shaft to form the mechanical seal. The teflon sealing ring may include graphite, polytetrafluoroethylene, and optionally, non-graphite carbon.
1 . A mechanical seal surrounding a rotary shaft to prevent a fluid from flowing across the seal, the seal comprising:
a rotatable seal ring comprising a rotatable seal face, wherein the rotatable seal ring is rotatable around a rotational axis of the rotary shaft;
a stationary seal ring spatially fixed relative to the rotatable seal ring and having a stationary seal face to engage the rotatable seal face to form the mechanical seal, wherein the stationary seal ring comprises:
about 1% to about 30%, by weight, graphite; and
about 70% to about 98%, by weight, polytetrafluoroethylene.
2 . The mechanical seal of claim 1 , wherein the stationary seal ring comprises about 1% to about 30%, by weight, of non-graphite carbon.
3 . The mechanical seal of claim 2 , wherein the stationary seal ring comprises about 3%, by weight, of the non-graphite carbon.
4 . The mechanical seal of claim 1 , wherein the stationary seal ring comprises about 5% to about 27% graphite.
5 . The mechanical seal of claim 1 , wherein the stationary seal ring comprises about 70% polytetrafluoroethylene.
6 . The mechanical seal of claim 1 , wherein the stationary seal face engages the rotatable seal face with a fluid that fills a gap between the two faces.
7 . The mechanical seal of claim 6 , wherein the fluid is air.
8 . The mechanical seal of claim 6 , wherein the rotatable seal face comprises a plurality of grooves formed in the seal face to conduct the fluid into the gap.
9 . The mechanical seal of claim 1 , wherein the rotatable seal ring comprises alumina, silicon carbide, or tungsten carbide.
10 . The mechanical seal of claim 1 , wherein a portion of the graphite from the stationary seal ring is deposited on the rotatable seal ring to form a graphite layer that is in contact with both the stationary seal face and the rotatable seal face.
11 . The mechanical seal of clam 1 , wherein the rotary shaft rotates at a rate of about 1750 rpm.
12 . The mechanical seal of claim 1 , wherein the seal comprises a gap between an inner diameter of the stationary seal ring and the rotary shaft.
13 . The mechanical seal of claim 12 , wherein an o-ring is positioned in the gap between the inner diameter of the stationary seal ring and the rotary shaft.
14 . The mechanical seal of claim 1 , wherein the seal comprises an elastic member circularly engaging the stationary seal ring to press the seal ring against the rotary shaft.
15 . The mechanical seal of claim 14 , wherein the elastic member is an o-ring or spring.
16 . The mechanical seal of claim 1 , comprising a compressive member coupled to the stationary seal ring to press the stationary seal face against the rotatable seal face.
17 . The mechanical seal of claim 1 , wherein the fluid is a gaseous hydrocarbon or water.
18 . The mechanical seal of claim 1 , wherein the seal is used in a dishwasher or a washing machine.
19 . A mechanical seal surrounding a rotary shaft to prevent a fluid from flowing across the seal, the seal comprising:
a stationary seal ring comprising a stationary seal face, wherein the stationary seal ring is positioned around the rotary shaft;
a rotatable seal ring that is rotatable relative to the stationary seal ring and having a rotatable seal face to engage the stationary seal face to form the mechanical seal, wherein the rotatable seal ring comprises:
about 1% to about 30%, by weight, graphite; and
about 70% to about 98%, by weight, polytetrafluoroethylene.
20 . The mechanical seal of claim 19 , wherein the rotatable seal ring comprises about 1% to about 30%, by weight, of non-graphite carbon.
21 . The mechanical seal of claim 19 , wherein the rotatable seal ring comprises about 3%, by weight, of the non-graphite carbon.
22 . The mechanical seal of claim 19 , wherein the rotatable seal ring comprises about 5% to about 27% graphite.
23 . The mechanical seal of claim 19 , wherein the rotatable seal ring comprises about 70% polytetrafluoroethylene.
24 . The mechanical seal of claim 19 , wherein the stationary seal ring comprises alumina, silicon carbide, tungsten carbide, steel, or stellites.
25 . A graphite containing teflon sealing ring used to form a mechanical seal around a rotary shaft, wherein the teflon sealing ring comprises a first seal face capable of engaging a second seal face on a second sealing ring surrounding the rotary shaft to form the mechanical seal, and wherein the teflon sealing ring comprises:
about 1% to about 30%, by weight, graphite; and
about 70% to about 98%, by weight, polytetrafluoroethylene.
26 . The graphite containing teflon sealing ring of claim 25 , wherein the teflon sealing ring comprises about 1% to about 30%, by weight, non-graphite carbon.
27 . The graphite containing teflon sealing ring of claim 25 , wherein the teflon sealing ring is stationary relative to the second sealing ring.
28 . The graphite containing teflon sealing ring of claim 25 , wherein the rotatable seal ring comprises about 3% of the non-graphite carbon.
29 . The graphite containing teflon sealing ring of claim 25 , wherein the rotatable seal ring comprises about 5% to about 27% graphite.
30 . The graphite containing teflon sealing ring of claim 25 , wherein the rotatable seal ring comprises about 70% polytetrafluoroethylene.
31 . The graphite containing teflon sealing ring of claim 25 , wherein the second sealing ring comprises alumina, silicon carbide, or tungsten carbide.