CA1236447A - Sealed valve - Google Patents
Sealed valveInfo
- Publication number
- CA1236447A CA1236447A CA000439391A CA439391A CA1236447A CA 1236447 A CA1236447 A CA 1236447A CA 000439391 A CA000439391 A CA 000439391A CA 439391 A CA439391 A CA 439391A CA 1236447 A CA1236447 A CA 1236447A
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- CA
- Canada
- Prior art keywords
- chamber
- sealing
- actuator
- piston
- space
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Abstract
A SEALED VALVE
ABSTRACT
The invention has especial utility for providing com-pletely safe hermetic sealing of actuators extending into highly sensitive or isolative process equipment, such as that using atomic radiation. The invention uses a gen-eral principle taught by the inventor's prior U.S. Pat.
No. 3,933,052. The actuator is hermetically sealed by the aid of a flexible diaphragm, and the diaphragm is made safe by pressure compensation. A sealing liquid confined on the outside of the hermetic diaphragm ap-plies the same pressure to the outside face of the dia-phragm as is applied by the process atmosphere to the inside face of the diaphragm. According to the embodi-ment illustrated in that patent, a diaphragm (actually a bellows) entirely separate from the actuator was ex-posed to the process atmosphere to apply its pressure to the sealing liquid. According to the present invention, a diaphragm which accommodates the movement of the actuator and accomplishes the hermetic sealing also transmits the pressure of the process atmosphere to the sealing liquid. The present invention also has some fea-tures of "fail-safe" nature and achieves other simplifica-tion. Also, it provides a temporary seal that permits servicing of the outer packing around the actuator.
ABSTRACT
The invention has especial utility for providing com-pletely safe hermetic sealing of actuators extending into highly sensitive or isolative process equipment, such as that using atomic radiation. The invention uses a gen-eral principle taught by the inventor's prior U.S. Pat.
No. 3,933,052. The actuator is hermetically sealed by the aid of a flexible diaphragm, and the diaphragm is made safe by pressure compensation. A sealing liquid confined on the outside of the hermetic diaphragm ap-plies the same pressure to the outside face of the dia-phragm as is applied by the process atmosphere to the inside face of the diaphragm. According to the embodi-ment illustrated in that patent, a diaphragm (actually a bellows) entirely separate from the actuator was ex-posed to the process atmosphere to apply its pressure to the sealing liquid. According to the present invention, a diaphragm which accommodates the movement of the actuator and accomplishes the hermetic sealing also transmits the pressure of the process atmosphere to the sealing liquid. The present invention also has some fea-tures of "fail-safe" nature and achieves other simplifica-tion. Also, it provides a temporary seal that permits servicing of the outer packing around the actuator.
Description
The invention of which the present disclosure is offered for public dissemination if adequate patent protection is available relates to the field of providing safe hermetic seals for actuators by which something inside of a highly isolative process apparatus may be actuated from the outside. The term "highly isolative" is used here with respect to apparatus from which nothing must be permitted to escape, an example being a nuclear reactor.
The essential principles of safe sealing used in this invention were taught by the applicant's prior United States Patent No. 3,933,052. Hermetic sealing of the actuator was accomplished by use of a diaphragm, actually a bellows, which permitted necessary movemen-t oE a par-t oE -the actuator while providing a hermetic seal be-tween :i-t and the highly isolative appara-tus. Such hermetic sealing by a diaphragm was old, but according to the underlying principle of that patent, it is given a previously unattained safety by confining a sealing liquid on the outside of the diaphragm and using it to apply to the outer face of the diaphragm a compensating pressure exactly equal to the pressure applied to the inner face by the highly isolative apparatus.
As is oEten the case, the structure worked out for initially embodying this principle was relatively co~plex. For example, it included three additional diaphragms or bellows besides the one forming the main hermetic seal. According to the present invention, a simplified diaphragm system is provided in which the equalized compensating pressure results from the fact that the diaphragm system can accommodate itself positionally to the volume of the confined sealing liquid which is therefore placed under this compensating pressure by the diaphragm system.
Specifically, the present invention provides a valve apparatus used in controlling fluid in a wo:rking environment and seallng the working environment from an external environment, said valve apparatus comprising: a valve housing having an external opening exposed to the external environment and having a chamber in communication with said external opening and said working environment, an actuator means mounted for longitudinal movement within said external opening and said chamber so as to control the fluid in the working environment, a first flexible membrane means disposed in said chamber and connected to said housing, a second flexible membrane means disposed within said chamber and connected to said actua-tor means, and a guiding means disposecl with.i.n sa:i.d chamber and movable rela-tive to said actuator means, said guiding means being connected to said Eirst and second flexible means so as to guide said first and second flexible means as said first and second flexible means move within said chamber.
The sealing liquid must ordinarily be confined behind the hermetic diaphragm by a non-hermetic seal such as one using packing rings or a rotary seal for the actuating shaft where it passes through the seal housing to the external atmosphere. According to the prior patent, the minute seepage of sealing liquid through such an outer seal caused no great difficulty because this sealing liquid could be replenished as needed through a separate valved replenish-ment port. Of course, if the packing gland deteriorates to the point of leaking badly, constant replenishment would become a problem. According to the present invention, lt is possible to replace the packing gland wlthout loss of the compensating pressure on the sealing liquid. This is accomplished by letting the ~i .. ~
~L2;~
diaphragm system extend, as the sealing liquid is lost through the outer seal, to a terminal position at which it creates a temporary seal between the outer seal and the confined sealing liquid. This temporary seal may serve both for maintaining the sealing liquid confined so that it can exert the compensating pressure on the diaphrgam and also to permit removal of the packing gland and its replacement.
The present invention also incorporates a fail-safe feature. There will be no disaster if there should be a failure to replenish the sealing liquid when some or much of it has leaked out through the packing. Ins-tead, the diaphragm sys-tem, as it expands to occupy the space left by the leak:Lng sealing liquid, comes to a safe terminal point. In one Eorm, at thls point -the dlaphragm is s~ructurally restrained in a manner -that prevents rupture of the diaphragm. In the other form a temporary seal is formed to prevent Eurther loss of liquid. Under either condition it may not be possible, or may be difficult, to operate the control actuator.
This seeming disadvantage is actually an advantage in that an operator who attempts to operate the actuator will realize that special servicing such as the supply of more sealing liquid is required.
~ dvantages of the invention will be more apparent from the following description, and from -the drawings.
FIGURE 1 is a sectional view, approximately along an axial plane, of one preferred form of the invention.
FIGURE 2 is a fragmentary view similar to FIGURE 1 but showing the diaphragm fully ex-tended.
FIGURE 3 is a sectional view of another preferred form ~36~7 of the invention, -taken approximately on an axial plane.
FIGURE 4 is a fragmentary view similar to a portion of FIGURR 3 but showing the terminal or fully extended position of the membrane system.
Although the following disclosure offered for public dissemination is detailed to ensure adequacy and aid understanding, this is not intended to prejudice that purpose of a patent which is to cover each new invention concept therein no matter how others may la-ter disguise it by variations in form or additions or further improvements. The claims at the end hereof are intended as the chief aid toward this purpose, as it is these that meet the require-ment of pointing out the parts, improvements, or combinations in which the inventive concepts are ~ound.
Both forms oE the present invention are concerned with maintaining a reliable hermetic seal between a movable actuator shaft 11 and an isolative apparatus 12 within which a valve or other piece of equipment is to be actuated by the actuator 11. The apparatus 12 is isolative in the sense that some process takes place within it that must be kept isolated from the surrounding atmosphere. One example is a nuclear reactor within which radio-active particles are in the process atmosphere which must not be allowed to escape even in minute quantities. The present invention assumes that relatively limited movement of the actuator 11 is a~1 that is required. In FIGURE 1, both limited pivotal movement and limlted longitudinal movement could be required, whereas in FIGURE
3 it is assumed that limited longitudinal movement is enough.
In FIGURE 1, the main element of the hermetic seal is a diaphragm 13 made of an elastomeric material immune to or highly :, 72309-l resistant to the process a-tmosphere. The material known as neoprene rubber is an example of an elastomer which would be suit-able for the diaphragm for a great many process atmospheres.
It may be assumed that the diaphragm 13 is molded to a shape having approximately the cross section shown in FIGURE 1, the shape being also described as generally tubular but doubled back.
One end of the tubular structure is sealed to shaft 11 by a ferrule-like hose clamp 14 while the other outer end of the tubular diaphragm structure is sealed between base plate 16 and flange 17 with sufficient clamping force developed by the screws 18 to ensure a hermetic seal. Although the base plate may be secured to the isolative apparatus 1.2 in a varlety of manners, perlpheral we]dlng has been lllustrated because of lts dependable nature as a hermetic seal.
It will be apparent that one face of the dlaphragm 13 which may be called its inner face is exposed to the process atmos-phere or working atmosphere of -the isolative apparatus 12. Accord-ing to the prior patent of the present inventor, the outer Eace of the dlaphragm 13 ls exposed to a seallng llquld whlch ls confined adjacent to the diaphragm so that lt can exert on the outer face of the diaphragm a pressure exactly or approxlmately equal to the pressure on the lnner face of the diaphragm 13 so as to protect the diaphragm 13 from any rupturing differential force which would otherwise result from a high pressure on the inner face of the diaphragm. According to the present invention, the sealing liquid is conflned with the space 21. Part of this space 21 is between the diaphragm 13 and housing 22 which is secured in place by its flange 17. The confined space 21 may also extend between the '~
~ 72309-1 diaphragm 13 and actuator 11.
In order for the sealing liquid to be confined within the space 21, there must be an outer seal between the housing 22 and the shaf-t 11. It must be capable of withstanding pressure equal to the process atmosphere pressure. Because the shaft 11 must move with respect to the housing 22, practical considerations dictate the use of a packing seal 23 or other rubbing type of seal. The packing may be kept under necessary pressure by a packing gland or nut 24.
Some means should be provided for forcing the sealing liquid into the space 21. This has been illustrated as a conven-tional nipple 26 for a grease gun. Such nipples conventionally i.nclude a ball check valve so that grease can be forced into the space 21 under pressure but cannot flow out from this space through the fitting 26. A plug type of seal may be provided if greater dependability is required. The light grease such as is commonly used in grease guns is an ideal type of sealing liquid.
Some means should be provided for knowing when the supply of liquid sealant in space 21 should be replenished through the nipple 26 (unless replenishing is automatic). According to FIGURE
1, the seepage of sealing liquid past the packing 23 is caught in a transparent jar 31 which may have thereon an indication of the level which, when reached by the escaped liquid wlthin the jar 31, indicates the need for supplying replacement liquid through nipple 26. Alternatively, the jar 31 could be graduated, with markings indicating the number of strokes of the grease gun needed to replace the escaped liquid. Of course, it is desirable that the quantity of escaping liquid be as small as possible. Hence, two sealing rings ,. ~ . ,, ~3~
23 have been shown between the drain por-t 33 and space 21. To be sure that all escaping liquid is trapped in jar 31, a third sealing ring 34 may be provided on the outside of a drain ring 36. The gland 24 compresses all of the seal rings 23 and 34 so that they spread to engage the actuator 11 with suita:ble pressure for forming a seal without causing objectionable resistance to the movement of actuator 11. In the event of continuing leakage of sealing liquid from space 21 without replenishment through nipple 26, diaphrgam 13 would eventually stretch to the position shown in FIGURE 2. It will be observed that there is still no danger of rupture of the diaphragm 13 by pressure of the isolative or process a-tmosphere against -the inner surEace of diaphragm 13, because subs-tan-tially the en-tire sur:Eace o:E d.iaphragm 13 is supported by either the inner surEace of housiny 22 or the sur:Eace oE sha.Et or ac-tua-to:r 11.
FIGURE 2 illustrates a visible clearance be-tween -the actua-tor 11 and the housing 22, but this is exaggerated for the sake of illustra-tion. There should be only enough clearance, if any, to ensure easy movement of the actuator 11. With such a small clearance, it is immaterial that the diaphragm will. be unsupported in the very small area where -this clearance is found. In fact, process pres-sure which might tend to burst the diaphragm 13 merely presses it firmly against both actuator 11 and the adjacent portion o-f housing 22 so as to form a temporary additional seal between the housing and the shaft. This permits replacing the packing rings 23, in the event that they have deteriorated to the point of permitting exces-sive leakage of the sealing liquid. Of course, to replace them the packing gland 24 is removed.
The surfaces supporting the diaphragm are smoothly con-~7 toured (free from corners) so that the diaphragm will not be sub-jected to excessive local stressing.
In some instances the elastomeric diaphragm of FIGURES 1 and 2 may be undesirable and the use of metal bellows may be pre-ferred. If rotation or substantial pivoting of the actuator is required, a sealed drive such as that of the prior patent mentioned may be needed. However, if only longitudinal movement of the actuator is required a bellows system having considerable resem-blance to the features of FIGURES 1 and 2 may be used, as shown in FIGURE 3. Here, the shaft or actuator llA is shown extending into an isolative apparatus 12. It might, however, extend merely to or toward the isolative apparatus, termlnating at a point short oE the appar~tus where it coulcl perEorm such a function as press:ing a con-trol button.
The hermetic seal in this instance is illustrated as a bellows system including an outer bellows 41, an inner bellows 42, and a piston 43 to which both of the bellows are hermetically attached as by brazing. The lower end of bellows 41 is hermetically attached to housing base 46 and the lower end of bellows 42 is hermetically attached to actuator llA. Thus, the bellows system forms a hermetic seal between the housing base 46 and the actuator llA. The housing base 46 is provided with a flange 47 which is hermetically attached, as by peripheral welding, to the isolative apparatus 12.
One of the reasons why an elastomeric diaphragm may be unsuitable is if the temperature of the isolative atmosphere might be too high for it. With such high temperatures in mind, the hous-ing base 46 has been illustrated with cooling fins 48. If .
.
~23~ 72309-1 necessary, there could be further cooling as by circulating a cooling medium which, after absorbing heat from the seal structure would pass through a heat-dissipating radiator and return. The cooling medium could be the sealing liquid, being drawn from and returned to the confined sealant space 21 wi.thin the housing 49 and outside of the bellows system 41, 42 and 43. Of course, the circu-lating cooling system should, in this instance, be hermetically sealed and of a nature to be a branch of the confined space 21.
The piston 43, in FIGURE 3, preferably has a free-sliding fit with housing 49, and either a free-sliding fit or a slight clearance around actuator 11~. It is thus able -to accommodate itself to the quantity of seallng liquid confined withln space 21, much of which wil:l usually be above piston ~3. The p.i.ston ~3 will therefore transmit to the sealing liquid the pressure of the iso-lative atmosphere, so that the sealing liquid located externally of the bellows 41 and 42 will have the same pressure, or substantially the same, as the isolative atmosphere. Thus, there will be the compensation descri.bed in the prior patent so that the pressure of the internal atmosphere will have no tendency to rupture the bellows.
FIGURE 3 illustrates diagrammatically a system for main-taining within the space 21 an ideal quantity of sealing liquid.
This is accomplished by automatically replenishing the liquid to whatever extent leakage occurs past packing rings 23. This auto matic replenishing system may be considered diagrammatic inasmuch as its details will be largely a matter o~ choice by a particular designer. It should have a constantly pressurized source 51 for the sealing liquid. The pressure should be a little higher than g ~i ~
,~
~2~;4~
any to be encountered in -the isolative atmosphere. If only moder-ate pressures will be in the isolative atmosphere, the source could be gravitational, such as a raised tank of the liquid. If very high pressures are to be encountered in the isolative atmos-phere, the source could be a closed tank of the sealing liquid with gas applied above it in the tank from a gas cylinder to maintain it under a predetermined pressure.
The pressurized source 51 should supply its sealing liquid through a valve 52 biased to the closed position but pressed open when piston 43 engages the tip of valve ball 53. This will press the valve ball 53 out of engagement with its seat so that the pressurized source can force sealing liquid into space 13, moving piston 43 downwardly (retracting it) untll it allows valve ball 53 to s~at and shut ofE the Elow oE sealing liquid.
In FIGURE 3, the condult between the pressurized source and valve 52 has been illustrated as including a check valve 56, an on-off valve 57 and a reducing valve 58. The check valve 56 pre-vents any loss of pressure on the sealing liquid in space 13 in the event of failure of the supply system. The on-off valve 57 wil~ be closed when it is desired to change the packing rings 23, as will be described. The reducing valve 58 may not be needed unless the pressure of the pressurized source would otherwise be much higher than the maximum expected pressure of the isolative atmosphere. If ~ a cylinder of pressurized or liquified gas is the source of the ; pressure, this reducing valve would be in a different position, where it controls the gas pressure.
With automatic replenishing system illustrated in FIGURE
3, the leakage-trapping jar 31 is less needed than in FIGURE 1, but .
. .:
~ 2~ ~
~ ~v ~ ~ 72309-1 lt may be provided anyway as a matter of cleanliness and so that need for replacing packing rings 23 can be detected. In the event of the excessive leakage of these packing rings, the valve 57 will be closed so that the leakage will allow piston 43 to move upwardly until it squeezes O-ring 61 to form a temporary seal between housing 49 and actuator llA as seen in FIGURE 4. With this temporary seal, the nut or gland 24 may be removed to permit replacement of the packing rings 23. The attendant's practice will probably be to loosen gland 24 as soon as he has closed valve 57, so that the seal-ing liquid will quickly leak through packing rings 23 until O-ring 61 has been sufficiently distorted to effectuate its temporary seal.
When -the leakage stops, the attendant will remove gland 24 and replace the packing rings 23. Ile will then reopen valve 57 which will supply enough replacement sealing liquid to thrust the piston 43 downwardly (retracting it) until it allows valve ball 53 to seat and shut off the replacement flow of sealing liquid.
As the piston 43 is moved away from O-ring 61, the O-ring would return to its normal position in which it is out of con-tact with actuator llA so as not to be worn or flattened by the movements of this actuator. It can hold itself in place by resilient engagement of its outer peripheral surface with housing 49. Also, housing 49 could be provided with a lip extending slightly under the greatest diameter of O-ring 61 to ensure its retention.
Although anyone desiring to use this invention will prob-ably do his own engineering, some effort has been made to illus-trate the invention in practical form. It is assumed that much of the assembly will be performed before the housing 22 or 49 is ,: :
~3~ 72309-1 applied. Access to clamping ring 14 may then be achieved by raising the outer portion of diaphragm 13. Likewise, access to brazing the lower end of bellows 42 to actuate llA can be achieved by upwardly compressing the bellows 41.
From the foregoing, it is seen that an improved and simplified device using the principles of this applicant's prior United States Patent No. 3,933,052 has been provided. In this instance, the same membrane which forms the flexible hermetic seal between the transmission means or actuator and the seal housing transmits to the compensating sealing liquid on the extrior of the membrane the pressure of the working a-tmosphere. This is accom-plished by havlng a portion oE the membrane accommodate i-tself in its position to the quantity oE conEined sealing liquid. This, in turn, requires an excess of the diaphragm material so that a portion of it can move independently of the actuator.
In addition the improved pressure-compensated sealed transmission device of the present invention has "fail-safe" charac-teristics. If the outer seal for the transmission means should fail, or if the attendant fails to replenish sealing liquid which has slowly seeped through this outer seal, the membrane still will not be subjected to a rupturing danger resulting from a high differential between the internal and external pressures, because the membrane must stretch to a point at which it is Eully protected.
It may be that the transmission means may no longer work easily but that fact will warn the attendant that the device needs replenish-ment of the liquid. Indeed, the ideal would be to incorporate some automatic locking device which prevents operation of the trans-mission means while it is stretched to the limit.
.
,~ .
;~236~
72309-l In 1-ts preferred forms, the present invention also forms a temporary seal between the confined sealing liquid and the outer seal, when the limit in stretching (or the terminal position) has been reached, so that the outer seal may be serviced, as by replac-ng it.
One preferred form of the invention includes automatic means for replacing the sealing liquid as needed. Stretching of the membrane to the terminal point, with the advantages previously mentioned, would thus only occur in the event of failure of the automatic replenishing device, or in the unli]cely event that the outer seal failed so thoroughly as to let leakage exceed the supply furnished by -the automatic replenishing device. A preferred Eorm oE the automatic replenishing device can be shut oEE, when ServiCinCJ
of the outer seal is desired, to permit the membrane to stretch to its terminal point and produce the temporary seal mentioned.
~t ~
,
The essential principles of safe sealing used in this invention were taught by the applicant's prior United States Patent No. 3,933,052. Hermetic sealing of the actuator was accomplished by use of a diaphragm, actually a bellows, which permitted necessary movemen-t oE a par-t oE -the actuator while providing a hermetic seal be-tween :i-t and the highly isolative appara-tus. Such hermetic sealing by a diaphragm was old, but according to the underlying principle of that patent, it is given a previously unattained safety by confining a sealing liquid on the outside of the diaphragm and using it to apply to the outer face of the diaphragm a compensating pressure exactly equal to the pressure applied to the inner face by the highly isolative apparatus.
As is oEten the case, the structure worked out for initially embodying this principle was relatively co~plex. For example, it included three additional diaphragms or bellows besides the one forming the main hermetic seal. According to the present invention, a simplified diaphragm system is provided in which the equalized compensating pressure results from the fact that the diaphragm system can accommodate itself positionally to the volume of the confined sealing liquid which is therefore placed under this compensating pressure by the diaphragm system.
Specifically, the present invention provides a valve apparatus used in controlling fluid in a wo:rking environment and seallng the working environment from an external environment, said valve apparatus comprising: a valve housing having an external opening exposed to the external environment and having a chamber in communication with said external opening and said working environment, an actuator means mounted for longitudinal movement within said external opening and said chamber so as to control the fluid in the working environment, a first flexible membrane means disposed in said chamber and connected to said housing, a second flexible membrane means disposed within said chamber and connected to said actua-tor means, and a guiding means disposecl with.i.n sa:i.d chamber and movable rela-tive to said actuator means, said guiding means being connected to said Eirst and second flexible means so as to guide said first and second flexible means as said first and second flexible means move within said chamber.
The sealing liquid must ordinarily be confined behind the hermetic diaphragm by a non-hermetic seal such as one using packing rings or a rotary seal for the actuating shaft where it passes through the seal housing to the external atmosphere. According to the prior patent, the minute seepage of sealing liquid through such an outer seal caused no great difficulty because this sealing liquid could be replenished as needed through a separate valved replenish-ment port. Of course, if the packing gland deteriorates to the point of leaking badly, constant replenishment would become a problem. According to the present invention, lt is possible to replace the packing gland wlthout loss of the compensating pressure on the sealing liquid. This is accomplished by letting the ~i .. ~
~L2;~
diaphragm system extend, as the sealing liquid is lost through the outer seal, to a terminal position at which it creates a temporary seal between the outer seal and the confined sealing liquid. This temporary seal may serve both for maintaining the sealing liquid confined so that it can exert the compensating pressure on the diaphrgam and also to permit removal of the packing gland and its replacement.
The present invention also incorporates a fail-safe feature. There will be no disaster if there should be a failure to replenish the sealing liquid when some or much of it has leaked out through the packing. Ins-tead, the diaphragm sys-tem, as it expands to occupy the space left by the leak:Lng sealing liquid, comes to a safe terminal point. In one Eorm, at thls point -the dlaphragm is s~ructurally restrained in a manner -that prevents rupture of the diaphragm. In the other form a temporary seal is formed to prevent Eurther loss of liquid. Under either condition it may not be possible, or may be difficult, to operate the control actuator.
This seeming disadvantage is actually an advantage in that an operator who attempts to operate the actuator will realize that special servicing such as the supply of more sealing liquid is required.
~ dvantages of the invention will be more apparent from the following description, and from -the drawings.
FIGURE 1 is a sectional view, approximately along an axial plane, of one preferred form of the invention.
FIGURE 2 is a fragmentary view similar to FIGURE 1 but showing the diaphragm fully ex-tended.
FIGURE 3 is a sectional view of another preferred form ~36~7 of the invention, -taken approximately on an axial plane.
FIGURE 4 is a fragmentary view similar to a portion of FIGURR 3 but showing the terminal or fully extended position of the membrane system.
Although the following disclosure offered for public dissemination is detailed to ensure adequacy and aid understanding, this is not intended to prejudice that purpose of a patent which is to cover each new invention concept therein no matter how others may la-ter disguise it by variations in form or additions or further improvements. The claims at the end hereof are intended as the chief aid toward this purpose, as it is these that meet the require-ment of pointing out the parts, improvements, or combinations in which the inventive concepts are ~ound.
Both forms oE the present invention are concerned with maintaining a reliable hermetic seal between a movable actuator shaft 11 and an isolative apparatus 12 within which a valve or other piece of equipment is to be actuated by the actuator 11. The apparatus 12 is isolative in the sense that some process takes place within it that must be kept isolated from the surrounding atmosphere. One example is a nuclear reactor within which radio-active particles are in the process atmosphere which must not be allowed to escape even in minute quantities. The present invention assumes that relatively limited movement of the actuator 11 is a~1 that is required. In FIGURE 1, both limited pivotal movement and limlted longitudinal movement could be required, whereas in FIGURE
3 it is assumed that limited longitudinal movement is enough.
In FIGURE 1, the main element of the hermetic seal is a diaphragm 13 made of an elastomeric material immune to or highly :, 72309-l resistant to the process a-tmosphere. The material known as neoprene rubber is an example of an elastomer which would be suit-able for the diaphragm for a great many process atmospheres.
It may be assumed that the diaphragm 13 is molded to a shape having approximately the cross section shown in FIGURE 1, the shape being also described as generally tubular but doubled back.
One end of the tubular structure is sealed to shaft 11 by a ferrule-like hose clamp 14 while the other outer end of the tubular diaphragm structure is sealed between base plate 16 and flange 17 with sufficient clamping force developed by the screws 18 to ensure a hermetic seal. Although the base plate may be secured to the isolative apparatus 1.2 in a varlety of manners, perlpheral we]dlng has been lllustrated because of lts dependable nature as a hermetic seal.
It will be apparent that one face of the dlaphragm 13 which may be called its inner face is exposed to the process atmos-phere or working atmosphere of -the isolative apparatus 12. Accord-ing to the prior patent of the present inventor, the outer Eace of the dlaphragm 13 ls exposed to a seallng llquld whlch ls confined adjacent to the diaphragm so that lt can exert on the outer face of the diaphragm a pressure exactly or approxlmately equal to the pressure on the lnner face of the diaphragm 13 so as to protect the diaphragm 13 from any rupturing differential force which would otherwise result from a high pressure on the inner face of the diaphragm. According to the present invention, the sealing liquid is conflned with the space 21. Part of this space 21 is between the diaphragm 13 and housing 22 which is secured in place by its flange 17. The confined space 21 may also extend between the '~
~ 72309-1 diaphragm 13 and actuator 11.
In order for the sealing liquid to be confined within the space 21, there must be an outer seal between the housing 22 and the shaf-t 11. It must be capable of withstanding pressure equal to the process atmosphere pressure. Because the shaft 11 must move with respect to the housing 22, practical considerations dictate the use of a packing seal 23 or other rubbing type of seal. The packing may be kept under necessary pressure by a packing gland or nut 24.
Some means should be provided for forcing the sealing liquid into the space 21. This has been illustrated as a conven-tional nipple 26 for a grease gun. Such nipples conventionally i.nclude a ball check valve so that grease can be forced into the space 21 under pressure but cannot flow out from this space through the fitting 26. A plug type of seal may be provided if greater dependability is required. The light grease such as is commonly used in grease guns is an ideal type of sealing liquid.
Some means should be provided for knowing when the supply of liquid sealant in space 21 should be replenished through the nipple 26 (unless replenishing is automatic). According to FIGURE
1, the seepage of sealing liquid past the packing 23 is caught in a transparent jar 31 which may have thereon an indication of the level which, when reached by the escaped liquid wlthin the jar 31, indicates the need for supplying replacement liquid through nipple 26. Alternatively, the jar 31 could be graduated, with markings indicating the number of strokes of the grease gun needed to replace the escaped liquid. Of course, it is desirable that the quantity of escaping liquid be as small as possible. Hence, two sealing rings ,. ~ . ,, ~3~
23 have been shown between the drain por-t 33 and space 21. To be sure that all escaping liquid is trapped in jar 31, a third sealing ring 34 may be provided on the outside of a drain ring 36. The gland 24 compresses all of the seal rings 23 and 34 so that they spread to engage the actuator 11 with suita:ble pressure for forming a seal without causing objectionable resistance to the movement of actuator 11. In the event of continuing leakage of sealing liquid from space 21 without replenishment through nipple 26, diaphrgam 13 would eventually stretch to the position shown in FIGURE 2. It will be observed that there is still no danger of rupture of the diaphragm 13 by pressure of the isolative or process a-tmosphere against -the inner surEace of diaphragm 13, because subs-tan-tially the en-tire sur:Eace o:E d.iaphragm 13 is supported by either the inner surEace of housiny 22 or the sur:Eace oE sha.Et or ac-tua-to:r 11.
FIGURE 2 illustrates a visible clearance be-tween -the actua-tor 11 and the housing 22, but this is exaggerated for the sake of illustra-tion. There should be only enough clearance, if any, to ensure easy movement of the actuator 11. With such a small clearance, it is immaterial that the diaphragm will. be unsupported in the very small area where -this clearance is found. In fact, process pres-sure which might tend to burst the diaphragm 13 merely presses it firmly against both actuator 11 and the adjacent portion o-f housing 22 so as to form a temporary additional seal between the housing and the shaft. This permits replacing the packing rings 23, in the event that they have deteriorated to the point of permitting exces-sive leakage of the sealing liquid. Of course, to replace them the packing gland 24 is removed.
The surfaces supporting the diaphragm are smoothly con-~7 toured (free from corners) so that the diaphragm will not be sub-jected to excessive local stressing.
In some instances the elastomeric diaphragm of FIGURES 1 and 2 may be undesirable and the use of metal bellows may be pre-ferred. If rotation or substantial pivoting of the actuator is required, a sealed drive such as that of the prior patent mentioned may be needed. However, if only longitudinal movement of the actuator is required a bellows system having considerable resem-blance to the features of FIGURES 1 and 2 may be used, as shown in FIGURE 3. Here, the shaft or actuator llA is shown extending into an isolative apparatus 12. It might, however, extend merely to or toward the isolative apparatus, termlnating at a point short oE the appar~tus where it coulcl perEorm such a function as press:ing a con-trol button.
The hermetic seal in this instance is illustrated as a bellows system including an outer bellows 41, an inner bellows 42, and a piston 43 to which both of the bellows are hermetically attached as by brazing. The lower end of bellows 41 is hermetically attached to housing base 46 and the lower end of bellows 42 is hermetically attached to actuator llA. Thus, the bellows system forms a hermetic seal between the housing base 46 and the actuator llA. The housing base 46 is provided with a flange 47 which is hermetically attached, as by peripheral welding, to the isolative apparatus 12.
One of the reasons why an elastomeric diaphragm may be unsuitable is if the temperature of the isolative atmosphere might be too high for it. With such high temperatures in mind, the hous-ing base 46 has been illustrated with cooling fins 48. If .
.
~23~ 72309-1 necessary, there could be further cooling as by circulating a cooling medium which, after absorbing heat from the seal structure would pass through a heat-dissipating radiator and return. The cooling medium could be the sealing liquid, being drawn from and returned to the confined sealant space 21 wi.thin the housing 49 and outside of the bellows system 41, 42 and 43. Of course, the circu-lating cooling system should, in this instance, be hermetically sealed and of a nature to be a branch of the confined space 21.
The piston 43, in FIGURE 3, preferably has a free-sliding fit with housing 49, and either a free-sliding fit or a slight clearance around actuator 11~. It is thus able -to accommodate itself to the quantity of seallng liquid confined withln space 21, much of which wil:l usually be above piston ~3. The p.i.ston ~3 will therefore transmit to the sealing liquid the pressure of the iso-lative atmosphere, so that the sealing liquid located externally of the bellows 41 and 42 will have the same pressure, or substantially the same, as the isolative atmosphere. Thus, there will be the compensation descri.bed in the prior patent so that the pressure of the internal atmosphere will have no tendency to rupture the bellows.
FIGURE 3 illustrates diagrammatically a system for main-taining within the space 21 an ideal quantity of sealing liquid.
This is accomplished by automatically replenishing the liquid to whatever extent leakage occurs past packing rings 23. This auto matic replenishing system may be considered diagrammatic inasmuch as its details will be largely a matter o~ choice by a particular designer. It should have a constantly pressurized source 51 for the sealing liquid. The pressure should be a little higher than g ~i ~
,~
~2~;4~
any to be encountered in -the isolative atmosphere. If only moder-ate pressures will be in the isolative atmosphere, the source could be gravitational, such as a raised tank of the liquid. If very high pressures are to be encountered in the isolative atmos-phere, the source could be a closed tank of the sealing liquid with gas applied above it in the tank from a gas cylinder to maintain it under a predetermined pressure.
The pressurized source 51 should supply its sealing liquid through a valve 52 biased to the closed position but pressed open when piston 43 engages the tip of valve ball 53. This will press the valve ball 53 out of engagement with its seat so that the pressurized source can force sealing liquid into space 13, moving piston 43 downwardly (retracting it) untll it allows valve ball 53 to s~at and shut ofE the Elow oE sealing liquid.
In FIGURE 3, the condult between the pressurized source and valve 52 has been illustrated as including a check valve 56, an on-off valve 57 and a reducing valve 58. The check valve 56 pre-vents any loss of pressure on the sealing liquid in space 13 in the event of failure of the supply system. The on-off valve 57 wil~ be closed when it is desired to change the packing rings 23, as will be described. The reducing valve 58 may not be needed unless the pressure of the pressurized source would otherwise be much higher than the maximum expected pressure of the isolative atmosphere. If ~ a cylinder of pressurized or liquified gas is the source of the ; pressure, this reducing valve would be in a different position, where it controls the gas pressure.
With automatic replenishing system illustrated in FIGURE
3, the leakage-trapping jar 31 is less needed than in FIGURE 1, but .
. .:
~ 2~ ~
~ ~v ~ ~ 72309-1 lt may be provided anyway as a matter of cleanliness and so that need for replacing packing rings 23 can be detected. In the event of the excessive leakage of these packing rings, the valve 57 will be closed so that the leakage will allow piston 43 to move upwardly until it squeezes O-ring 61 to form a temporary seal between housing 49 and actuator llA as seen in FIGURE 4. With this temporary seal, the nut or gland 24 may be removed to permit replacement of the packing rings 23. The attendant's practice will probably be to loosen gland 24 as soon as he has closed valve 57, so that the seal-ing liquid will quickly leak through packing rings 23 until O-ring 61 has been sufficiently distorted to effectuate its temporary seal.
When -the leakage stops, the attendant will remove gland 24 and replace the packing rings 23. Ile will then reopen valve 57 which will supply enough replacement sealing liquid to thrust the piston 43 downwardly (retracting it) until it allows valve ball 53 to seat and shut off the replacement flow of sealing liquid.
As the piston 43 is moved away from O-ring 61, the O-ring would return to its normal position in which it is out of con-tact with actuator llA so as not to be worn or flattened by the movements of this actuator. It can hold itself in place by resilient engagement of its outer peripheral surface with housing 49. Also, housing 49 could be provided with a lip extending slightly under the greatest diameter of O-ring 61 to ensure its retention.
Although anyone desiring to use this invention will prob-ably do his own engineering, some effort has been made to illus-trate the invention in practical form. It is assumed that much of the assembly will be performed before the housing 22 or 49 is ,: :
~3~ 72309-1 applied. Access to clamping ring 14 may then be achieved by raising the outer portion of diaphragm 13. Likewise, access to brazing the lower end of bellows 42 to actuate llA can be achieved by upwardly compressing the bellows 41.
From the foregoing, it is seen that an improved and simplified device using the principles of this applicant's prior United States Patent No. 3,933,052 has been provided. In this instance, the same membrane which forms the flexible hermetic seal between the transmission means or actuator and the seal housing transmits to the compensating sealing liquid on the extrior of the membrane the pressure of the working a-tmosphere. This is accom-plished by havlng a portion oE the membrane accommodate i-tself in its position to the quantity oE conEined sealing liquid. This, in turn, requires an excess of the diaphragm material so that a portion of it can move independently of the actuator.
In addition the improved pressure-compensated sealed transmission device of the present invention has "fail-safe" charac-teristics. If the outer seal for the transmission means should fail, or if the attendant fails to replenish sealing liquid which has slowly seeped through this outer seal, the membrane still will not be subjected to a rupturing danger resulting from a high differential between the internal and external pressures, because the membrane must stretch to a point at which it is Eully protected.
It may be that the transmission means may no longer work easily but that fact will warn the attendant that the device needs replenish-ment of the liquid. Indeed, the ideal would be to incorporate some automatic locking device which prevents operation of the trans-mission means while it is stretched to the limit.
.
,~ .
;~236~
72309-l In 1-ts preferred forms, the present invention also forms a temporary seal between the confined sealing liquid and the outer seal, when the limit in stretching (or the terminal position) has been reached, so that the outer seal may be serviced, as by replac-ng it.
One preferred form of the invention includes automatic means for replacing the sealing liquid as needed. Stretching of the membrane to the terminal point, with the advantages previously mentioned, would thus only occur in the event of failure of the automatic replenishing device, or in the unli]cely event that the outer seal failed so thoroughly as to let leakage exceed the supply furnished by -the automatic replenishing device. A preferred Eorm oE the automatic replenishing device can be shut oEE, when ServiCinCJ
of the outer seal is desired, to permit the membrane to stretch to its terminal point and produce the temporary seal mentioned.
~t ~
,
Claims (13)
1. A valve apparatus used in controlling fluid in a working environment and sealing the working environment from an external environment, said valve apparatus comprising:
a valve housing having an external opening exposed to the external environment and having a chamber in communication with said external opening and said working environment, an actuator means mounted for longitudinal movement within said external opening and said chamber so as to control the fluid in the working environment, a first flexible membrane means disposed in said chamber and connected to said housing, a second flexible membrane means disposed within said chamber and connected to said actuator means, and a guiding means disposed within said chamber and movable relative to said actuator means, said guiding means being connected to said first and second flexible means so as to guide said first and second flexible means as said first and second flexible means move within said chamber.
a valve housing having an external opening exposed to the external environment and having a chamber in communication with said external opening and said working environment, an actuator means mounted for longitudinal movement within said external opening and said chamber so as to control the fluid in the working environment, a first flexible membrane means disposed in said chamber and connected to said housing, a second flexible membrane means disposed within said chamber and connected to said actuator means, and a guiding means disposed within said chamber and movable relative to said actuator means, said guiding means being connected to said first and second flexible means so as to guide said first and second flexible means as said first and second flexible means move within said chamber.
2. The valve apparatus as set forth in claim 1 wherein said first flexible membrane means is a first impervious bellows means and said second flex-ible membrane means is a second impervious bellows means.
3. The valve apparatus as set forth in claim 1 wherein said guiding means is a piston which is guided for movement within said chamber by said actuator means.
4. The valve apparatus as set forth in claim 1 wherein said chamber is cylindrically shaped having an outer cylindrical wall and wherein said guiding means is a piston which is guided for movement in said chamber by said outer cylindrical wall.
5. The valve apparatus as set forth in claim 1 including sealing means disposed adjacent said external opening, said guiding means movable to engage said sealing means to seal the external opening from said chamber.
6. A valve apparatus used in controlling fluid in a working environment and sealing said working environment from an external environment comprising:
a valve housing having an external opening exposed to the external environment and having a chamber in communication with said external opening and said working environment, an actuator means mounted for longitudinal movement within said external opening and said chamber so that said fluid is controlled by the movement of said actuator means, a piston means disposed within said chamber and movable in said chamber relative to said actuator means, a first bellows means having a first end connected to said housing and a second end connected to said piston means, a second bellows means having a first end connected to said actuator means and a second end connected to said piston means, a first space within said chamber in communi-cation with said working environment, a second space within said chamber in com-munication with said external opening, said second space being sealed from said first space by said piston means and said first and second bellows means, a first sealing means sealing said external opening from said external environment, and a sealing liquid disposed within said second space.
a valve housing having an external opening exposed to the external environment and having a chamber in communication with said external opening and said working environment, an actuator means mounted for longitudinal movement within said external opening and said chamber so that said fluid is controlled by the movement of said actuator means, a piston means disposed within said chamber and movable in said chamber relative to said actuator means, a first bellows means having a first end connected to said housing and a second end connected to said piston means, a second bellows means having a first end connected to said actuator means and a second end connected to said piston means, a first space within said chamber in communi-cation with said working environment, a second space within said chamber in com-munication with said external opening, said second space being sealed from said first space by said piston means and said first and second bellows means, a first sealing means sealing said external opening from said external environment, and a sealing liquid disposed within said second space.
7. The valve apparatus as set forth in claim 6 wherein said piston means is guided by said actuator means and said housing so that said piston means guides said first and second bellows means as said first and second bellows means move within said chamber.
8. The valve apparatus as set forth in claim 6 including second sealing means disposed rela-tive to said external opening, said piston means being engageable with said second sealing means to seal said external opening from said second space.
9. The valve apparatus as set forth in claim 6 including replenishment means to provide addi-tional sealing liquid to said second space, said replenishment means being controlled by said piston means to provide said additional sealing liquid to said second space.
10. The valve apparatus as set forth in claim 9 wherein said replenishment means includes a pressurized source of additional sealing liquid and a valve means, said valve means being opened as said piston means moves within said chamber toward said external opening to provide additional sealing liquid to said second space and being closed upon the movement of said piston means away from said external opening.
11. In combination with a valve apparatus used in controlling fluid in a working environment and sealing said working environment from an external environment, said valve having a valve housing having a external opening exposed to the external environment and having a chamber in communication with said exter-nal opening and said working environment, having an actuator means controlled from the external environment so as to control liquid within the working environment, said actuator means extending through said external opening and said chamber and having a first sealing means sealing the external opening from said external environment, a valve sealing mechanism comprising:
a first flexible membrane means disposed in said chamber and connected to said housing, a second flexible membrane means disposed within said chamber and connected to said actuator means, and a movable piston disposed within said chamber so as to be movable relative to said actuator means, said piston being connected to said first and second flexible membrane means such that said first and second flexible membrane means and said piston means provide said chamber with first and second spaces, said first space being in communication with said working environ-ment and said second space being in communication with said external environment.
a first flexible membrane means disposed in said chamber and connected to said housing, a second flexible membrane means disposed within said chamber and connected to said actuator means, and a movable piston disposed within said chamber so as to be movable relative to said actuator means, said piston being connected to said first and second flexible membrane means such that said first and second flexible membrane means and said piston means provide said chamber with first and second spaces, said first space being in communication with said working environ-ment and said second space being in communication with said external environment.
12. The valve sealing mechanism as set forth in claim 11 including a second sealing means disposed relative to said external opening such that said piston is engageable with said second sealing means to seal said second space from said external opening.
13. The valve sealing mechanism as set forth in claim 11 including a sealing liquid in said second space so that the pressure in said first and second space so that the pressure in said first and second spaces are maintained substantially equal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000439391A CA1236447A (en) | 1983-10-20 | 1983-10-20 | Sealed valve |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000439391A CA1236447A (en) | 1983-10-20 | 1983-10-20 | Sealed valve |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1236447A true CA1236447A (en) | 1988-05-10 |
Family
ID=4126332
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000439391A Expired CA1236447A (en) | 1983-10-20 | 1983-10-20 | Sealed valve |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1236447A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5474303A (en) * | 1993-04-15 | 1995-12-12 | Coles; Carl R. | Actuator rod hermetic sealing apparatus employing concentric bellows and pressure compensating sealing liquid with liquid monitoring system |
| WO2017049366A1 (en) * | 2015-09-24 | 2017-03-30 | Weir Minerals Australia Ltd | A flexible sealing arrangement for a valve or pump |
| USD926944S1 (en) | 2019-11-25 | 2021-08-03 | Joseph P. Marcilese | Fluid connector |
-
1983
- 1983-10-20 CA CA000439391A patent/CA1236447A/en not_active Expired
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5474303A (en) * | 1993-04-15 | 1995-12-12 | Coles; Carl R. | Actuator rod hermetic sealing apparatus employing concentric bellows and pressure compensating sealing liquid with liquid monitoring system |
| WO2017049366A1 (en) * | 2015-09-24 | 2017-03-30 | Weir Minerals Australia Ltd | A flexible sealing arrangement for a valve or pump |
| USD926944S1 (en) | 2019-11-25 | 2021-08-03 | Joseph P. Marcilese | Fluid connector |
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