Valve with improved seal

A valve assembly including an annular ring having an inwardly directed projection and a seal having a groove into which the projection is fitted. The seal has a sealing surface which engages a valve member. The seal has two ribs which project from the sealing surface and a protrusion extending into the groove, the ribs and the protrusion engaging respectively the valve member and the annular ring for providing a bubble-tight seal.

BACKGROUND OF THE INVENTION 
This invention relates generally to valves and more particularly to gate 
and other similar type valves having an improved seal member associated 
with a valving member. 
With valves of the type noted above, the valve member seal arrangement 
includes a groove in a valve body or in a supporting ring structure in 
which the seal member is often retained by an adhesive. The seal member 
includes a sealing surface which engages the valve member to form a bubble 
tight seal. In the construction using an adhesive, the seal member which 
may be a rubber ring, protrudes from a valve seat surface so that when the 
valve is closed, there is an interference between the valving member and 
the rubber ring thereby effecting the bubble-tight seal. 
However, there are many problems associated with the adhesively retained 
seal arrangements. Since the temperature and media limits are not as good 
as the elastomer used in the seal, premature seal failure results. Also, 
the flexing of the seal caused by the frictional drag of the valve member 
upon the seal breaks down the mechanical retention properties of the 
adhesive until the bond fails. At this point, the seal moves into the 
pathway of the valve member and is ruined. Improper installation due to 
the application of too much adhesive or irregularly applied adhesive can 
cause the seal to fail. In addition, the different set up and cure times 
of adhesives can cause difficulties. Another problem associated with 
adhesively retained seals is that of replacing the seals in the field 
which entails a time consuming and often difficult process of removing the 
old adhesive from the groove. With respect to valves of the knife gate 
type, when the adhesive fails, the seal tends to bunch up and be sliced by 
the knife edge of the gate. 
In addition, seals which are retained by means of an adhesive physically 
confine the seal material along its inner diameter restricting flowability 
of the seal material. While prior seals have included ribbed portions on 
the sealing face, the ribbed structure has not permitted sufficient room 
for the material of the seal to flow when the seal is fully compressed. 
This restricting of the flowability of the material of the seal causes the 
seal to be pinched between the knife gate and the valve seat and damaged. 
OBJECTS OF THE INVENTION 
It is therefore an object of the present invention to provide a valve and 
an associated seal and a mounting structure therefor which overcome the 
disadvantages of the prior art. 
It is an additional advantage of the present invention to provide a seal 
which is easily installed and removed from a valve seat. 
It is a further object of the invention to provide a seal which will not be 
pinched and damaged during operation of the valve member. 
It is yet another object to provide a knife gate valve and seal arrangement 
which provides a bubble-tight seal. 
SUMMARY OF THE INVENTION 
These objects and others which will become apparent hereinafter are 
accomplished by the present invention which provides an annular seal which 
is retained on a valve body. The valve body has a passageway formed by 
inlet and outlet portions and a valve member which is mounted for movement 
in the passageway between an open and a closed position. The annular seal 
cooperates with the valve member and has a groove which permits seating of 
the seal on a projection which extends into the passageway from the valve 
body. The seal has a reinforcing ring of a rigid material which is 
embedded therein and which extends along the periphery of a portion of the 
groove which is closest to the sealing face and which is adjacent the 
upstream side of the projection. 
Preferably, two ribs extend from the seal face and one seal bead extends 
from the groove of the seal ring permitting retention of the seal on the 
ring and providing a fluid tight structure when the seal is in engagement 
with the knife gate.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
In FIG. 1, there is shown a knife gate valve 8 including a valve body 10 
having a fluid passageway 12 which includes an inlet section 14 and an 
outlet section 16. A gate 18 is reciprocally and slidably mounted in the 
valve body 10 between the inlet section 14 and the outlet section 16. The 
gate 18 slides from an open position (not shown), where the gate 18 does 
not obstruct the flow of fluid through the passageway 12, to a closed 
position where the gate 18 prevents the flow of fluid through the 
passageway 12. An actuator assembly (not shown) is associated with the 
gate 18 to move it between its open and closed positions and may take the 
form of a conventional hand operated screw assembly. In this arrangement, 
the valve body 10 is a fabricated housing with inlet section 14 and outlet 
section 16 and a chest area 15 in which the gate 18 is slidably mounted. 
Other embodiments include a cast valve body 10 with the chest 15, inlet 
section 14 and outlet section 16 and seat 24 integral to the casting. In 
valves of this type, at least one seal assembly cooperates with a planar 
surface of a gate to prevent fluid flow through a passageway. Some 
embodiments, as illustrated in FIGS. 1 and 2 include two seal assemblies, 
one for the upstream planar surface and another for the downstream planar 
surface. Other embodiments include only one seal assembly usually located 
on the upstream side as illustrated in FIG. 3. Only one seal assembly will 
be described since the other is the same. 
The seal assembly includes an annular ring 24 which has a "T" shaped 
cross-section. As is clearly illustrated in FIGS. 2 and 3, the flat top 
portion 26 of the "T" is secured to the valve body 10, and a leg 28 of the 
"T" projects inwardly into the passageway 12 adjacent the gate 18. While 
the ring 24 has been described and illustrated as having a "T"-shaped 
cross-section, any other configuration in which a projection extends from 
the valve seat inwardly into the passageway 12 will be satisfactory. Such 
other configuration may include an L-shaped projection or a leg integrally 
formed on the valve body 10. 
Reference is now made to FIG. 4. An annular seat ring or seal 30 is made of 
a resilient material which is impervious to the fluid flowing in the 
passageway 12. Such resilient material may be rubber, neoprene or the 
like. The seal 30 has a sealing face 32 located adjacent the gate 18. The 
sealing face 32 and the gate 18 are adapted to cooperate with each other 
to form a bubble-tight seal. The seal 30 also includes an oppositely 
disposed planar face 34. A radially outer peripheral surface 35 of the 
seal ring 30 is formed with a U-shaped groove 36. The size of the groove 
36 is such that it fits onto the leg 28 of the annular ring 24 and in 
close engagement therewith. The seal 30 is located on the leg 28 with the 
groove 36 tightly seated thereon. A bottom section 50 adjacent the planar 
face 34 may extend the same distance as surface 35. In larger seals, the 
bottom section 50 may be recessed, in order to permit easier installation 
of the seal 30. 
A rigid ring insert 38 is embedded in the seal 30. The rigid ring insert 38 
has a substantially round cross-section and is made of stainless steel, 
fiber glass, plastic or other rigid material. The rigid ring insert 38 is 
not restricted to a round cross-section but may also be square or any 
other suitable shape. The rigid ring insert 38 is located in the annular 
ring 24 so that it is adjacent the side surface 40 of the groove 36 
closest to the sealing face 32. When the seal member 30 is located on the 
leg 28, the rigid ring insert 38 bears against the upstream side of the 
projecting leg 28. In this way, the forces of the fluid which bear against 
the gate 18 when in its closed position will not cause the seal 30 to 
become displaced from the annular ring 24 and thereby result in fluid 
leakage. 
A seal bead 42 extends from the side surface 40 of the groove 36 at its 
junction with the peripheral surface 35. When the seal 30 is positioned on 
the ring 24, the seal bead 42 engages the upstream side of the projecting 
leg 28 with an interference fit, thus affecting zero leakage around the 
backside of the seal 30. A grommet-like lip 50 wraps around the downstream 
side of projecting leg 28 locking the seal 30 in place. Thus, the seal 30 
is securely retained on the ring 24. The insert 38 is preferably molded 
into the seal 30 so that it is surrounded over a major portion of its 
surface by the resilient material forming the seal. The bead 42 is thus 
conveniently formed during the molding operation. 
The sealing face 32 is corrugated. In this embodiment it has two projecting 
ribs or beads 44, 46 separated by a trough 45. The rib 44 is formed on the 
radially inward surface 47 of the seal so that it is closest to the flow 
passageway. The rib 46 is positioned radially outwardly of rib 44 and 
extends adjacent the surface 35 and the valve body 10. The rib 46 
protrudes a greater outward distance from the trough 45 than the rib 44. 
This configuration provides better sealing capability at low differential 
pressures. In a typical size valve, the rib 46 extends from the trough 45 
a distance of 0.005 inches further than the rib 44. It has been found that 
this distance provides optimum sealing conditions. When the valve is 
closed, the ribs 44 and 46 engage a planar surface of the gate 18. The 
positioning of the gate 18 against the ribs 44 and 46 causes compression 
of the seal 30. During compression, the ribs 44 and 46 are deformed and 
the seal 30 is compressed approximately 22 percent. It has been found that 
compression of the seal 30 to a maximum of 22 percent provides an 
effective sealing arrangement when the gate 18 is in its closed position 
and must withstand the forces of the fluid which bear against the surface 
of the gate 18. Greater amounts of compression overstress the seal 30 and 
cause the the tear resistance of the seal to decrease resulting in 
premature deterioration thereof. The following equation will give the 
compression percentage: 
##EQU1## 
The dimensions represented by A and B are measured as indicated in FIGS. 5 
and 2, respectively. The width A represents the uncompressed condition of 
the seal 30 when the gate 18 is not in engagement therewith. The width B 
represents the compressed condition with the sealing face 32 engaging the 
gate 18. In the compressed condition the seal material flows so as to fill 
the trough 45 and present a substantially planar surface in contact with 
the gate 18. 
The rigid ring insert 38 prevents the seal 30 from being dislodged from the 
leg 28 by the frictional drag caused by the movement of the gate 18 
against the seal 30. Thus, displacement of the seal 30 out of the annular 
ring 24 and into the passage way 12 is eliminated. This also prevents 
slicing of the seal 30 by the gate 18 due to the frictional drag on the 
seal 30 as it proceeds between its closed and open positions causing 
radial movement of the seal 30. 
Due to the configuration of the sealing face 32 and the protruding ribs 44 
and 46 and the fact that the inside diameter of the seal 30 is not 
confined because of the resiliency of the material thereof, the 
compression of the seal 30 when the gate 18 is in engagement therewith 
permits the material of the seal 30 to flow. This further minimizes the 
chance of pinching of the seal 30. 
The ribs 44 and 46 together with the seal bead 42 provide a bubble-tight 
seal between the gate 18 and the seal 30 both at the sealing face 32 and 
at the back portion of the seal 30 adjacent the annular ring 24. 
FIG. 5 illustrates generally the seal 30 positioned on the annular ring 24. 
FIG. 2 illustrates one embodiment of the invention in a bi-directional gate 
valve in which a valve seal surrounds both the inlet section 14 and the 
outlet section 16 of the passageway 12 and one seal 30 is positioned on 
each of the valve seats. 
FIG. 3 illustrates a second embodiment of the invention in which one seal 
30 and one "T" shaped annular ring 24 are used in a gate valve which 
performs a uni-directional shut off function. In this figure, the gate 18 
in its closed position is situated between the seal 30 and a body wedge 48 
on the valve body 10. The arrow indicates the direction of flow of the 
fluid material. 
While the seal of the invention has been described with particular 
reference to an annular ring and a knife gate valve, it is to be noted 
that the seal may be used in other types of valves such as swing check 
valves and with other valve seat arrangements. 
While I have described the principles of my invention in connection with 
specific apparatus, it is to be clearly understood that this description 
is made only by way of example and not as a limitation to the scope of my 
invention as set forth in the objects thereof and in the accompanying 
claims.