CA2182843C - Pressure equalization valve - Google Patents

Abstract

A pressure equalization valve for alternatingly equalizing pressures between a first fluid source and at least two second fluid sources is disclosed. The pressure equalization valve includes a valve body, which includes a first port in fluid communication with the first fluid source and at least two second ports in fluid communication with the at least two second fluid sources, respectively, and a valve gate movable between a first equalizing position, wherein the valve gate allows fluid flow through one of the second ports and restrains fluid flow through another of the second parts to equalize substantially the fluid pressure between the first fluid source and one of the second fluid sources, and a second equalizing position, wherein the valve gate restrains fluid flow through the one of the second ports and allows fluid flow through the other of the second ports to equalize substantially the fluid pressure between the first fluid source and another of the second fluid sources. The valve further includes a chamber in the valve body between the first part and the second ports, wherein, as measured in planes perpendicular to the central axis of the first port, a largest cross sectional area of the chamber is at least 10 times larger the smallest cross sectional area of the first port.

Description

B~-~,~~C"~QUNI~ ~F; rNVENTIUN
Field of the ~~vention The present invention relates to devices useful for equalizing fluid pressures. More particularly, the present invention relates ro pressl,xre equalization valves useful. for eqtzalizirg fluicx x:>rwssr.ax:ves between plural fluid sources.
i L I v=
As shown in Fig. ~~, which ~~ ~ diagram of a prior art material handling system, an aa_rlock, such as an airlock 1, is a device used for the transfer, by gravity, of fly ash or ot.~-ier d~:~v, ~:~~F~r,.~ ~~l~:~w:a.rn:~ gx~anu~Lar solids from one pres~~ure zone t.o ancathe2.~. For example, in the system of Fig, 1., granu:Lax~ scv:l :~.<~.s ~:ar ~e ca.L:lected in an overhead hopper 2 and are dropped ~i.xrta the airlo<~k 1 in controlled volumes througri aperatiun of a pneumatically-operated valve 3. Each controlled volume of granular solids is then dropped, by means cf another pneumatically-operated valve 4, into a conveying pipe 5 carrying a supply of pressurized ~~~~~nv~:yin.g fluid, such as air. The air in the con~,revin.g pipe _~~ generally compressed up t:o 20 ~>si., but u~ay bd::a cwampressed up too 25 psi.
Because the pressurized conveying fluid is normally at a much higher pressure than the r~.ea.r--atmosphex°ic pressure inside the ai.r.l.c~e~> .a_, toe pressure differential would slow down the movement: of ,?c.a~..:id~~ from t:hc~ airlock 1 into t;he pipe 5 if it:. wex°c~ r~.ot eq~x~~l.i.~,ed. Accordingly, prior art material handling systems such as that shown in Fig. i often include a pressure equalization valve 6.
With reference ~o Fic~ . 1 and F"igs . 2 ~-3 , whi~:.~h illustrate two pz:ior ax-t c~c~~za.l:~z<:xt: i.c>n va:l.ues E7 , , 6..
equalization vales t~ ~ , 6" each ::~r:~c:.inaci.e a pcari~ 7, , 7", respectively, in fluid cocncnurrication witru an air_Lock 1 via a fluid l ine 7 , a por*: ~s ' , f3 " , respect ively, in fluid communication wit=h a c:onvey~..ng pipe 5 at. point 5a via a fluid line 8 , and a port '::~ , , ~" , respect: iveiy, i.n. fluid communication wit:~h a r~coppra~ ~% ~r_i.a a fluid :LinE~ 9. Each ., equalization valve c~' , 6" alF~o i.nr°:l.udes valve gates 10' , 10", respectively, operab:l_e :~y an actuator 11', 11", respectively, f.or alternG~.t.elt~~ ~Na1_:~w.rZcl the ports t3' , 9' and 8", 9", respective.ly.
An equalization valve F~ , 6 ' , ~:~ "' normally operates as follows. Before a volume of granular solids is dropped from the hopper z into the ~~ Lrl.or~l~: ':i., the valves 3, 4 are in a closed position. 'rhe actuator 'a~.', 11", respectively, i.s in a pos:it:io:rr suc::~u t.ta.at. the port: ~3' , g..
respectively, is sealed and t:he port ~~', 9" is open. The hopper 2 and the airlc~c.~k 1 t:xx:~= thr.r:~ ir:, fluid communication, and the pressure off: the air in the hopper 2 above the sol i.c3s a.r~d t=he px~~=sstz:rv~ ref the ai:r a_n t:he airlock 1 are nearly equal and nearly at atmospheric pressure. The volume caf c~x~an.ul.ar- ~~olids is then dropped into the airlock 1 by operlirag and timed closing of the valve 3 , and t:he actuat:ar ~.:1 ' , ~y..''' , respectively," i.s then operated so that the part 8' , 8e', xespec:tively, is open and the port ~' , 9" , xvespe~t:i.vely, i.~~ sealed. The conveying pipe 5 is thus :in fluid comrr~uriication with the airlock 1 at point 5a, azxd t}ve pressure of th.e air in the airlock 1 thus nearly equalizes to the much higher pressure of the air in the ec~r~vey:img pipe 5 at point 5a.
The pressures normally da not comp..~etely equalize because of the pressure drops inherent in ~.~.he system. The entire pressure equali.zratiora proc~es;~ t.z.sua:L:iy takes no morES than 5-15 seconds, depending on the volume of the airlock 1.
The solids 4~re glen d.:~:c3pped :~r~tc> the conveying pipe 5 at point 5c by the openi.n.g of the. valve 4, and are carried away through the pipE:~ 5. ~:t should be noted that the pressure of the air at I::lne poir t ~~c .l.s much lower than at the point 5a (and thus in t:.he airlock lj, because an orifice is interposed i.r~ t:ne p:~.~:re ~~ at point !=3b intermediate points 5a and 5c~:. The resultant pressure drop between the air:l.ock amcl poixnt: 5~ encourages tree flow of solids into the pipe 5. When the valve 4 is c:°losed, some residual solids generally x~errw~.n in the airlock 1.
The actuator 11' , 11" , ~:espec:t:.:i.we.'i..y, ~..s. t,hen opE~rate~d to seal the port 8', 8". ~.°espectively, and to open the port 9', 9'", respec:ti.vely, such t:k~.~t t::~~.e. ai:rlock 1 anc:l the hopper 2 are again in fluid communication and the pressure of the a~.r in th.e airlock 1 c:axl equalize with the near-atmospheric pressure of t~m ,aix in the hopper 2.
During each pressure equal.i.z~.t.z.on proc.~ess, the velocity of the a:ir passing ttz:r~~>uc~l~t the. egualiaation valve 6' , 6"
can reach almost sonic speedsr due to the extreme pressure diffE~rential :~etweera. th~~ ~~i:r in the Conveying pipe 5 and the airlock 1, and then the airlock 1 and the hopper 2 . Tn dddit.ian, cl~ax: a.xig tne:e p~wssure equaL:ization process between the airlo~:k 1 and t..he hopper 2 , the air flowing through t:he equalizK~tion v~~:l.ve 6 ° , 5" no:~.-mally entrains a significant amount. of loose granular solids from the airlock 1, which, a:u.x-lso7_i.c~s n~ixtu:re :is normally very abrasive when flowing at high speeds.
Prior art pressure equa~.izst:~on valves 6', ~" have significant disadvantages. first, such valves 6', 6"
tend to have very rapid wear rates, especially with respect to the valve party t~~' , 9 P° , the ~ralve gates 10 ° , 10" and the actuators 7_~1.', 11", respectively, which are cyclically subjected to b:.laats «tc~x~an.ular articulates ._ entrained in air streams mr~vi.rig at:. ne~ax°-sonic speeds , It has been estimated that wear rates on such parts are proportional t<:~ Ya3, where ~r _i:eqr..r.al. to =she velocvit:y of the air-solids mixture. ~'ox° some prier art equalization valves 6, it is not uncon°inlon for l:~ne wa.Lves 6 to require replacement within three months a:f= being put into service.
Further, pressure equalization valves such as the valves 6' , ~" are desi.gnec~. such th~rt::, when an actuator 11', 11", respectively,, is operated to move between port sealing positions, the:r.e is a pe:rlcad of time where both the port 8', 9' and the port 8"', ~~", respectively, are open, allowing p:e.ess~zre e~~~~:ra:7..~.zat~c~}n k~etween the a:i-dock l, the hopper 2 and the conveying pipe 5 all at the same time . In systems that are vac:uurn--c:~per~ated, as opposed to the pressurized system shower :in Fig. 1, this transient three--way equali.zaticn has been x_c:~~.nd t.U result:. :i.n the suction of granular solids ix°ao r:~m. vacuum pumps, and thus increased maintenaricE~ of. 51.1.C.'.~i pumps .
In view of the abcwe, It is are object of the present invention to ;provide at7. -i.rrsp:rt~~veci p.x-es~~u:r°e equalization valve.
Tt is another object. of the present invention to provide a pres:~ure equal a.zat-:a.on va:k.we that wears a1. a relatively slow rate,.
A further object of tine pxesexrt i..nvention is to provide a px~essu.~~e equ~ali.zat:::i.o:n ~aa::k..w~~ that restrains unintended transient equalization of fluid sources"
Another object of the pr went invention is to provide a pre~~sure equali.z,:~t~:i_orm<~a..lrc::~ having int:rnal components that are re:.i_at ivel: yy wea~:~ resistant .
Yet another object cf t:~~e present. invention is to provide a pressure equali.zat~.oxa. valve ~vavirm~ .z.z~a.t:errzal componEmts that are relatively easy to service arid .rep l..ac:e .
SUMMARY ~ '' T~~V~NTION
The above objects as well a.;~ other objects not.
specifically enumerated are accomplished by a pressure equalizat:i.an valve, for ai.tex ~ati.ngly equalizing pressures between a first fluid source and at. least two second fluid sources, in acc:oz°darac.e w~l..t:.t~ ~::t~e pxv~sent invention. The pressure equalization valea of the present invention includes a valve body, w~o.i.ch i.nc l.~,zc~es a f first port in fluid communication with the first fluid source and at least. two second ports ire f.-luid commun~i.catiorl w~~.th the at ~.e<~st two second fluid sources, respectively, and a valve gate movable between a first: equalizin.c~ pc:~sitiaay wherein the valve gate allows fluid flow through one of the second ports and restrains flu_Ld flow t~nrc~u.<:~~1 anorhE-~:r c:~f the seco:rad ports to equalize substantially the aiuid pxwessure between the first fluid source and one of tree second fluid sources, and a second equalizing pasitier~, wherein trie valve gate restrains fluid flow through the on.e a:E th~~ c,ec:.c>r~d po:rt;~ and allows fluid flow through the other of t~~~E:~ second ports to equalize substantially the flwici prc~ssure bc7twee~.z the f_Lrst fluid source and another of the second fluid sources. The valve further includes a chamber ir:c the val..ve body between the first port and tYie sec:and ports, wtnerein, as measured in planes perpendicular to the c~er~t~Pa~~ axis of the first port, the largest cx°oss sectional area c~fthe chamber :i.s _ t, ..

substantially largez than the snuallest cross sectional area of the first ;porn .
The objects of the ~..nve~~t.ian ,ire also accomplished by a pressure equalization valve, ~.or ~ltex~nat'ingly equalizing pressures betwee:ri a f first; f l~a.id sc~~.zrce~ a.nd at least. twa second fluid sources, that izicludes a valve body which includes a first. port. L~u f -~ o.~w.d corrlrcwnicatio:n with the first fluid source and at least. t:.wo second xaarts in florid communication with the at least twa second fluid sources, respectively, means fox rc,m~t::k::~o:llir~c;~ t.tue flow a:E t laid through the second ports to ~~ll..ow fltaa.d to flaw through the second parts alternately, anet nat~ simultaneously, to equalize the f_lul.d pre ssurr~ k~etweexr. th.e first fluid source and the second fluid saurc~es alternately, and means, in the valve body connected betweex~ the first port and the second ports, for substantially :xwc~uc~:i.n~,~ t;.he velocity of fluid flowing from the first port to at least one of the second ports.
_ y _ :~I~.ZEI~. ~,7FSCR,~1~~Q.1~~' .INGS_ The preferread embod~..menr s of '~h~. present invention will be described in greater detai.:l. with reference to the accompanying drawings, wraere:in like members like reference numerals and wherein;
Fig. 1. is a diagram of r~ pri.or an:t material handling system;
Fig. 2 i:~ a cross se~c~t~.ic.7nal vWi_ew of a prior a~°t pressure equalization valve;
Fig. 3 i:~ a cross sectional v:.E~w of another prior art pressure equalization valve Fig. 4 is a front elevat::ional view of a first embodiment of a pressure ~~c~ual.:izat::~i...oza valve o.f t~~7e present invention;
Fig. 5 is a cross sectional ~ri.ew along line V-~V of Fig.
4;
Fig. 6 is a cross sectional view along line VI-VI of Fig. 4;
Fig, 7 is a cross se~:ti.c~nal view along line VII-VII of Fig. 6; and Fig. 8 is a view sx.rnila~v tc~ Fig. F~ of a second embodiment of the pressurve egual.iz,-~.tac:~n valve of the present invention.
D T ' D p~, -, T
With referexnce t.o Fi.gs. 4--rvi, <~~ p~::essure equalization valve 16 in accordance with a first embodiment of the present inventVion inc:lvdes a valves body 18, a first: port 22 in fluid communication with a first f~..uid source, such as air within the airlock 1 :ire the material handling system of Fig. x., and a pair of second ports 24, 26 in fluid communication with a pair of secor°ic3 fluid sources, such as air within the ric~pper 2 a~n'~ ~:>ressr.~x i.zed a:ix w:i.t2n.i..n the conveying pipe 5, respectively. As shown in Fig. 5, the first port 22 i s Z.ocated a l c~rcg a f a rst wall 28 0:1: t;he valve body 18, and the seconr3. ports ~?4, 26 a.re located along a.
second wall 30 of the val4~e body 1~~, which second wall 30 is directly opposite the fixst. wall 28, Moreover, a central axis A c:of_ the (first port 22 and a central axis E~ off= the sec~:5mc1 pork: ~;4 lie along pc:~rt.ions of the same line (see Figs. 5 and 6), and the second port 26 is angled acutely by about ~.0-15 degrees relative to that: line, such that the central axis C o~ the second port 26 lies along a line that is acute7.y an.glc~c~ rc~~.ative to the axis A
by about 10-15 degrees arzd teat ext.ericis into the first port 26 (see Fig. 5) . The :~i.cyzz:i.:Ei.cancc of: these feat~.zres will be explained furr_her here:i.nbelow .
'fhe valve 16 also ir~ca~.~zcaes a piston 32 slidingly connected to a cylinder (mot showzy az:d pivotally connected to a link 34 by a pin 36. ':rhe liz~rk 34 is pivotally connected to a link 38 by a pin 40, and the link 38 is fixed to a pivot pin 42 to restrain rotat:.ion of the link 38 relative to the pivot pin. 42. Within the valve body 18, a valve actuator. 44 is fixed tc_s the x>ivat pin 42 such that rotation of the valve actwatc>r 44 z::°elative to thf~ ~>ivot pin 42 is also restrained. Ana c:varz :be seer: izn Figs, r~ and '7, the valve actuator.- 44 is a:~c~ugt~zl.y trr:iazrgul.ar in shape, and includes a paa..r of hollow cJy~:i.z:~dr~r;al extensions 46 therein.
An elongated ovoid valve ~~at:;~: 50 prveferab:ly made of: ground Ni-hard and having a pair of aolid car°lindrical extensions 52 ., ,_ thereon is provided such than the ~~ol~d extensions S2 are slidingly mounted within the holl.o~v extensions 4~. Each of the hollow extensions 46 includes a spring, such as a coil spring 56, therein to spr~..z~g bias i:..he valve gate 50 away from the valve actuator 44. '.T'he valvE>. body 18 further includes a va_Lve seat. p.latk5 ~at3 pr~~~erably made o:f around Ni-hard and attached on an inner surface of the second wall 30. The valve seat plate S8 has a paa..r of openings 60, 62 therein to form coplanar vs.lve seat::s 64, 66, respectively, at the two second ports 24, ~6. Because the °v~alwe gate 50 is spring bia sed away from the. vaa!.ve actuator 44, it is also spring biased against t:he va:l_ve seat plate 58. As will be discussed further hereinbel.ow, t~°ie valve gate 5U acts as means to control the flow of fluid through the second parts 24, 20 alternately.
All mater. ials of which t:he va7 ve 16 is const:_ructed preferably have ~ '750 deg,x~e~:a E~ahrerrhei.t temperat~.zre: rating.
The valve body I8 further inc7.~zdes a Chamber 70 intermediate the first and second walls 28, 30, respects.vely, arid th~,:m bet~wee~ra th~~ f3_rst port 22 arid the a. ~ _ second ports 24, 26, res~;~c-ct:~.vel-~r" 'fire chamber '?0 is very large relative to the ports 22, 2~, 2E~. Thus, when measured in planes perpendicul.a~~ t:r~ t~~e ce.r~t:.ra~i. axis A of the first port 22, such as planes c:ontaini:~g the lines D and E shown in Fig. 6, the largest cr.°oss sect:ic3na? area of the chamber 70 is substantially larg~:x t:;:ko.ar~ til<:~ srvallest cross sectional area of the first port 2~, as wall be discussed further hereinbelow.
With reference to Figs , 1 and 4--':j' , the structure and operation o.f the first embodiment cW the pressure equalization valve 1~ will ncv>w be r~x~>laiczed. As discussed above, the first port ~?2 is normally i..n fluid communication with a first flu id sou~~~ce , smc~.h a~ t~a.e air withi~:u t:he airlock 1 via the fluid litze 'T, orm second po:e~t '74 is normal ly in f 7_uid communi~.:.at ~ on wi.t:h one second f laid source, such as the tzoppe~~ ~? v:ia t:.t~.e fluid :Line .':~, and another second port 26 is ~mrmal~y i.rz fluid communication with another second fli.zid so~.arce, such as the conveying pipe 5 via the fluid line 8, rrL ~-~. :Lust equa:l.izing position, the valve actuator 4~ and the valve gate 50 are rotated roughly 80-85 degrees clockwa.se f:rTom the ~a~os:~t:i.on. shown :in Fig. 7.
The valve gate 50 is spra..ng ~ai.asec~ against and extends across the valve seat 56 t.ro r.:::ic:>se she opening 62, and thus fluid flow through the second port. 26 i.s restrained and fluid flow through the second port 24 is allowed by the valve gate 50. The va:lve~ qat;:e 50 woul..d be in the first equalizing position if the valve 1~ were being used in the system of_ Fig. 1 and a vc~l~zrnc-s ~~f c~z:~am;Glar solids was waiting to be dropped from th.e hoppex- 2 into the airlock 1., The hopper 2 and the airlock 1 would thus be in fluid communication, and the pressure of the ai.r in the hopper 2 above the solids and the pressure caf the air in ~:~he airlock 1 would be nearly equal. ai-~d rEet~r~l~~ atw atmospheric..° g>ressure .
The volume of granular solids could then be dropped into the airlock 1 by means of t:~he ~;ra~l.vc.=. 3.
When the piston 32 is cont.ro~.~.ed to retract and to pull the links 34, 38 clockwise ir-t l~ig. 4 and thus to rotate the pivot pin 42 clockwise in Fi.g. ~,, :rotation of the pivot pin 42 (counterclockwise irr F:ig. '7! causes the va.Lve actuator 44 and thus the valve gat:~:a 5i'~ t:.c:> r~ot.~~.~.r.e counterCloc)~wi.se in :1. _; _ Fig. 7 with the pivot pin ~'a. 'fhe va'~ve gate 50 thus moves from the first equalizing pos~t~on to an intermediate position, whe:rei:n t~~.e wal.vc c~-ste ~a:~ i...; spring biased against and e~ctends across both valve seatw~ ~a~ , 66 to close both openings 60, ~~2 and restrain fluid f3.ow through both second ports 24, 2~ . From this poi:v~t i:n L.t:~s movement, the valve gate 50 remains spring biased against the valve seat 64, but continued movement causes t.hk~ va L~r<.-a gate 50 to s:fide across the opening 66 until the wa .ve gate 5t~ is in a second equalizing posi.t:ion wherein the va~!.ve gate 50 is spring biased against. and exte~nd.s acY:ross c~~ral~~ robe valve seat 64 to close only the opening 60. I:n the second equalizing position, shown in F.i.g. 7, t~r.e v<~.~.vc~ swat 50 thu;r> restrains fluid flow through the secrorud ,~,~ort. 24 and allows fluid flow through the second port 2~ to equalize substantially the fluid pressure betwe=~r~ t:hc~ fi.rsi= i::l~:,i.d sou.rc~e anc~ the other second fluid source, if the val~,re 15 were being used in the system of Fig . 1. , the conveys ng p .pe 5 would thus be in fluid communication with the .air::i.ock I , and the pressure of the air in the airlock 1 would thus substantially equalize to the much higher pressure of the air in the conveying pipe 5. The pressures normal~.y wr,:>ulc~, runt completely equalize because of the pressure drops i.nhex~ent:. i.n the system. The solids would there be drapped into °_.he conveying pipe 5 by means of the va~.ve ~ and ~:~~r3-~.ed ~~way through the pipe 5 , When the piston 32 asd thus the valve actuator_ 44 are operated in reverse, the va:'L~tre gat~.~ 50 moves bac.~ through the intermediate posi..tion to the f~~.rst equalizing position, wherein fluid flaw through the second part 26 is restrained and fluid flow t:2~rough th.e ~;~:~~:ond ~:~c:~x~t: 24 is al.l~.:awEed, to equalize substantially th.e fi_uid px.~es5ure between the first fluid source and the ore sec:c~nd fluid source . I:f the valve 16 were being used with tr~~~ sy~ater~u caf F.ig. 1, thf.~ airlock 1 and the hopper 2 would again be in fluid communication and the pressure of the aW :- irx the air°~.oc~k 1 would substantially equalize with the near--atmc.>spher:io pressure of the air in the hopper 2.
During e~~ch presst.zre ec~~~a.l. iz~ti_on process, lt:he~ velocity of the fluid entering the ohamber 'r0 i.n the vale<a body 18, for example from the first port 22, may achieve almost sonic speeds, due to the extreme pressur~a differentials that it is expected would exist i.rr r:msrrrml. u~~a be~:;.ween the first and second fluid sources, re:;pect:: iuel.y. 3~cawever, be~:ause, as measured in planes perper~d_ic~.a.lar !~o t~ne~ central axis A of the first port 22, the largest cross sectional area of the chamber 70 is substantially larger than the smallest cross sectional area of the first port 2~.?, the velocity of a fluid flowing from the first pcs:rt: ~?2 t« ~:~ sc.:cond port, such as the second port 24, will be ~;iz~.~.~t.arzti<~::L.:l.~~ reduced.
This resu:l.t is c~:i.c::tated :k;y t~m:~: mass flow :rate equation, which states that for'<~ f_iu:id flowing through an enclosed space, the cross sectional area of the space multiplied by the velocity and density of the fluid equals a constant.
Thus, if the r:ro<~s sectional area of the space increases, the fluid velocity should. ciec~reac~t~ pzc~portiona:Llvy, assuming the density remains comstar~t . ~Jheru the fluid f1~::7wi_ng through the valve 16 cc~nsist~> of L_7~.~xryti.culate mat~r:er entrained in a gas, i.t has been found that the particulate matter generally remains entrained irl the gas while traveling through the chan~ber:~ '?0. Thus the dens.i_ty of the fluid remains fairly constant, alt:~.ough the density of the fluid does drop a fairly :i.nsignif:ic::ant:. amount due to normal pressure losses in the fl.a.zid l.~.nes ~anci the valve 15.
Accordingly, the increase>d cross s~.:cti.onal area of the chamber '70 appears to proc~l.ac~~ a su:k:ostantial reduc,t_i.on of the velocity of suc:in a fluid flowing through the chamber 70. In actual tests, a valve including a chamber having a largest cross sectional area o:F roughly 1!~ times the smallest cross sectional area of a f:i.r;~t pt;~:x-t. ha.~ k7ee,n found to have substantially improved we,ax° orates c:wex prior a:rt pressure equalization valves. Lt is ~:stimated that the velocity of the fluid flowing within such va.ive is reduced by about 14 times from a first port; to a second port. As stated above it is believed t=hat the; wea:r.~ rate ~~ars.es proportionally with v3, and it i.s t:hus estimat:.ed t_:rnat. the wear x~at:e c>n the valve actuator and the valve ga.C~e c>f suc:~la valve may be reduced by as much as 2,744 times. ~ec:ause c~f.tra.e exponential relation between velocity and wear rate, it is believed that a chamber 70 having a largest. r~ros s sect Tonal area of 10 times the smallest c:z°oras sect ioa:m~l area c.~f the first p~.~rt: 22 would _. G~ _.

substantially reduce the velocity i~f fluid flowing through the chamber, and wau3.d pz:oduc~: adv~;azzts:~geous wear rate results. In sucka a va _v~~, it: :Ls c;~:~tircrated that t:_hE~ fluid velocity would be reduced about 10 times, to produce a wear rate reduction on the order of 10~
In addition, it: :is i:rr_==l:i~~ved t::l~at the positioning of the second ports ;?9:, 26 on tree sec: and wall. 30 apposite the first part 22 , such that the central axe; 8, t. of the second ports 24, 2~ either l.ie an the central a~:is A of the first port 22, or are acutely axngled w:it:hi:n 7..()-l..~s degrees r~.~lative thereto and tkuus lie axl l~.:rue~ t: ha t:. e~r.end .i:nto t:lne first port 22, helps to reduce the wear x:~ate of the internal valve parts . Because c~f this pas:i t: ian:inc~ of t he second ports 24 , 26, a fluid f~'Lawa.ng i:rom the fi.rst~ port 22 to a ~~ec:ond port 24 or 26, or tx~arr~ a second i~c:~rt 24 ox° 26 to the ~:ix~st port 22, follows a relatively streamlixled flow path through the valve 16, thus s~.zbject_~ng t:he i.ntex-nal. valve parts to relatively lees direct bl.ast.a.ng f=rc;fm granular solids entrained in the fluid. Lxv additl.an, because the valve seat plate 58 and the valve gate 50 are made of ground Ni-hard, ~, o,. ..

they are relatively wear wesistant.
It should also be appreciated that because the valve gate 50 reaches the intermediate pr.~sit:ion wherein fluid flow through both of_ the second ports 24, a6 is restrained each time that it moves between t~~.e f ix::~t c~nd second equalizing positions, the valve 1~~ x~~str~~.ns ':~rar~sient cross equalization between the second fl~.z:~d sources. When the valve 15 is used wit;ru ;~ vvac:~.zxam syst::em, this feature is useful to rest:rc~in the uriiz~tf::nder.~ :f::l.c:~w of granular solids entrained in a fluid :into a vacuum pump, therelby reducing wear on and maintenance of the pump.
A further advantage of the prr:ser~t invention arises from the construction of the valve 16. Specifically, as can be seen in Figs . 4 and 6 , th~~ secor2d port s 24 , 2 6 , the 1 inks 34, 38, the pivot pin. 42, t~2f~ va2~lE~ actuator 44 and the valve gate 50 are all rnou:nt:.ert, d~x°r-:otly or ind:irr~ct:ly, to the second walk 30 of t~:hae va:! vca ~~r.~c:ly i 8, and the second wall 30 is mounted to the remainc~e r o:~ t. he valve body lf3 by six bolts 31. Thus, the valves= ac.tuator~ 4~ and the valve gate 50 may be easily serviced or replaced mezely by dis~~onnecting the piston 32 from the pz.ri :fit>, Lzz~sr.:rewing the :bolt: 31 and removing the second wa:l.l 30.
With ref erence to F'ig . 8 , a s~::cond embodiment of the pressure equali.zatiorr valve :~.1 > 4~af t~rE~ present irmesntion is illustrated, wherein parts ~:~f~ the ~rai_~,Fe 116 similar to parts of the valve 16 are numbered similarly, with the addition of 100 to the numbers. 'rhe v~x:L~re 1:16 i:~ structured and functions ident.ir,ally t.o thc~ valve L6, with o:ne exception.
Specifically, the valve 1:~6 includes an elongated chamber 170, and a valve body :1:18 c1f the ~,T~~.L~re~ 116 include; an elongated removable do«r 180, to allow on-sate maintenance of the valve 116. The removable door 180 is especially useful in on-site emergen~::~j s;iruua~:.~..cam:~;.
It should be appreci~ts~d t:hat:, a4 used throughout the specification and claims, the te:rrn "fl.uid" is used to refer broadly to any type of fl;x.ic~ ir~c:iuc.lix~g a gas, a gas/solid mixture, a ga:~jlz.quid. mixa~_z:r~:?, or G.a liquid. In ,~dc~ition, the term "fluid source" as ~zsed herei.r~ is used broadly to refer to any mass of fluid, including a mass under very high or very low pl:essure, ;~~zck~ ay wou~.c~l exist in a v,:~cuum system. It shou.l.d also be apprec:i~:~t~~c:~ that, while the ports 22, 24, 26 are :i1_lust.::rated aua.d des~:.~.ra.k>ed as being one piece with the valvf~ body :1.8, t.l~t~5y may ko:= sE:aparate pie~.es attached to the valve body 18, ~:~r may c~onsiat c:..f the terminal ends of fluid lines attached to the valve i~od~,~~ 18. Also, although the valve seat plate 5f3 and thus the valve seats 64, 66 are illustrated and described hez.-ein a~~ being separate from the valve body, the valve seat p~_ate ~>~ may be removed from the valve 16 such that the valve seats 64, 66 would consist of l0 the terminal ends of the ports 24, 26. Tn such an embodiment, the ports 24, 26 prefez-ably would be formed such that the valve seats 24, 26 were coplanar. Further, although the operating means for operating the valve actuator 44 to move the valve gate 50 is shown as including a piston 32, links 34, 38 anr~ pivot pin 42, other operating means, such as a rotary type of aca~uat.or, could :k~e used and the advantages of: the present: invert ~.c~n obtained thereby .
The principles, a prefe~~~red embodiment and the made of operation of the present. imvr~roticm have been desc::ribed in the foregoing specif_i.c~~ti~~tx. i~owt~jrp~:~:~, t: he invent.: ion which ~_ is intended to be protected ~~~ n~~r.:. Lc~ be construed as limited to the=_ particulax° embodimezit: c:lisc:losed. The embodiment is therefore to be regarded as illustrative rather than restrictive. ~Jariations and changes may be made by others wit7aout departi.nc~ from glue ~;~pirit of tine present invention.
Accordingly, it is e~cp.ressly intended that all such equivalents, variations and c~hange:~ which fall within the spirit and sccape of t:he present i.zv~~.le.rut::i.on as defined in the claims be emb:rar_ed t;he:reb~,~ .
G

Claims (23)

1. A pressure equalization valve for alternatingly equalizing pressures between a first fluid source and at least two second fluid sources, comprising:
a valve body including a first port in fluid communication with the first fluid source, said first port having a central axis, said valve body further including at least two second ports, each in fluid communication with a respective second fluid source, each said second port having a central axis wherein said central axis of at least one said second port forms an acute angle with said central axis of said first port;
a valve gate movable between a first equalizing position wherein said valve gate allows fluid flow through one of said second ports and restrains fluid flow through another of said second ports to substantially equalize the fluid pressure between the first fluid source and one of the second fluid sources, and a second equalizing position, wherein said valve gate allows fluid flow through said another of said second ports and restrains fluid flow through said one of said second ports to equalize substantially the fluid pressure between the first fluid source and another of the second fluid sources;
a valve seat at each of said second ports, said valve seat having a contact surface and wherein said valve gate has a contact surface adapted to slidably confront said contact surface of said valve seat, said valve gate and said valve seat being fabricated from Ni-Hard material such that, when a particulate material is introduced between said contact surface of said valve seat and said contact surface of said valve gate, said sliding confrontation of said contact surface of said valve seat with said contact surface of said valve gate causes said contact surface of said valve seat and said contact surface of said valve gate to become smoother; and a chamber in said valve housing between said first port and said second ports, wherein said chamber has a predetermined volume such that the velocity of fluid flowing between said first port and at least one of said second ports is substantially reduced.

2. The pressure equalization valve as claimed in claim 1, wherein a said predetermined volume of said chamber is at least 620 cubic inches.

3. The pressure equalization valve as claimed in claim 1 wherein as measured in planes perpendicular to the central axis of said first port, a largest cross-sectional area of said chamber is at least nine times larger than a smallest cross-sectional area of said first port.

4. The pressure equalization valve as claimed in claim 1, wherein said valve gate is further movable to an intermediate position intermediate said first and second equalizing positions, wherein said valve gate restrains fluid flow through both said second ports.

5. The pressure equalization valve as claimed in claim 1 wherein said contact surfaces of said valve seat and said valve gate have a flatness tolerance of at least 0.002 inches and a surface finish of at least 32 micro inches.

6. The pressure equalization valve as claimed in claim 1 wherein said valve gate is attached to a rotary actuator for moving said valve gate between said first and second equalizing positions.

7. The pressure equalization valve as claimed in claim 6, wherein said valve gate is adjustably biased away from said valve gate arm into sealing contact with said valve seat.

8. A pressure equalization valve as claimed in claim 1 further comprising a cover plate removably attached to said valve body, said cover plate having said second ports extending therethrough and said valve seat attached thereto and surrounding each said second port to sealingly confront said valve gate as said valve gate is moved between said first and second equalizing positions.

9. The pressure equalization valve as claimed in claim 8, wherein said rotary actuator is attached to said cover plate and has a rotatable actuator pin extending into said valve body and wherein said pressure equalization valve further comprises a valve gate arm attached to said actuator pin and said valve gate.

10. The pressure equalization valve as claimed in claim 1, wherein said central axis of at least one other said second port is coaxially aligned with said central axis of said first port.

11. The pressure equalization valve as claimed in claim 1 wherein at least some of said particulate material is wiped away from said contact surface of said valve seat as said contact surface of said valve gate slidingly engages said contact surface of said valve seat.

12. A pressure equalization valve for alternatingly equalizing pressures between a first fluid source and at least two second fluid sources, comprising:
a valve body including a first port in fluid communication with the first fluid source, said first port having a central axis, said valve body further including at least two second ports, each in fluid communication with a respective second fluid source, each said second port having a central axis wherein said central axis of at least one said second port forms an acute angle with said central axis of said first port;
a valve gate movable between a first equalizing position wherein said valve gate allows fluid flow through one of said second ports and restrains fluid flow through another of said second ports to substantially equalize the fluid pressure between the first fluid source and one of the second fluid sources, and a second equalizing position, wherein said valve gate allows fluid flow through said another of said second ports and restrains fluid flow through said one of said second ports to equalize substantially the fluid pressure between the first fluid source and another of the second fluid sources, said valve gate being further movable to an intermediate position intermediate said first and second equalizing positions, wherein said valve rate restrains fluid flow through both said second ports;
a valve seat at each of said second ports, said valve seat having a contact surface and wherein said valve gate has a contact surface adapted to slidably confront said contact surface of said valve seat, said valve gate and said valve seat being fabricated from Ni-Hard material such that, when a particulate material is introduced between said contact surface of said valve seat and said contact surface of said valve gate, said sliding confrontation of said contact surface of said valve seat with said contact surface of said valve gate causes said contact surface of said valve seat and said contact surface of said valve gate to become smoother; and a chamber in said valve housing between said first port and said second ports, wherein as measured in planes perpendicular to said central axis of said first port, a largest cross-sectional area of said chamber is at least nine times larger than a smallest cross-sectional area of said first port.

13. The pressure equalization valve as claimed in claim 12 wherein said contact surfaces of said valve seat and valve gate have a flatness tolerance of at least 0.002 inches and a surface finish of at least 32 micro inches.

14. The pressure equalization valve as claimed in claim 12 wherein said valve gate is attached to a rotary actuator for moving said valve gate between said first and second equalizing positions.

15. The pressure equalization valve as claimed in claim 12 further comprising a cover plate removably attached to said valve body, said cover plate having said second ports extending therethrough and said valve seat attached thereto and surrounding each said second port to sealingly confront said valve gate as said valve gate is moved between said first and second equalizing positions.

16. The pressure equalization valve as claimed in claim 15 further comprising:
a rotary actuator attached to said cover plate, said rotary actuator having a rotatable actuator pin extending into said valve body; and a valve gate arm attached to said actuator pin and said valve gate.

17. The pressure equalization valve as claimed in claim 16, wherein said valve gate is biased away from said valve gate arm into sealing contact with said valve seat.

18. The pressure equalization valve as claimed in claim 12, wherein said central axis of at least one other said second port is coaxially aligned with said central axis of said first port.

19. The pressure equalization valve as claimed in claim 12 wherein at least some of said particulate material is wiped away from said contact surface of said valve seat as said contact surface of said valve gate slidingly engages said contact surface of said valve seat.

20. A removable cover plate assembly for a pressure equalization valve having a valve body having a first port therein having a first central axis and being in fluid communication with a first fluid source, said removable cover plate assembly comprising:
a cover plate removably attachable to said valve body, said cover plate having at least two second ports each constructed for fluid communication with a respective second fluid source, each said second port having a central axis wherein said central axis of at least one said second port forms an acute angle with respect to the central axis of at least one said first port when said cover plate is attached to said valve body;
a valve seat attached to said cover plate adjacent to each said second port, said valve seat having a contact surface;
a valve gate movably attached to said cover plate and being constructed for sliding confrontation with said valve seat between a first equalizing position in which the valve gate permits fluid flow through one of said second ports and restrains fluid flow through another of said second ports to equalize substantially fluid pressure between the first fluid source and one of said second fluid sources and a second equalizing position wherein said valve gate restrains fluid through said one of said second ports and permits fluid flow through said other of said second ports, said valve gate having a contact surface adapted to slidably confront said contact surface of said valve seat, said valve gate and said valve seat being fabricated from Ni-Hard material such that, when a particulate material is introduced between said contact surface of said valve seat and said contact surface of said valve gate, said sliding confrontation of said contact surface of said valve seat with said contact surface of said valve gate causes said contact surface of said valve seat and said contact surface of said valve gate to become smoother; and a rotary actuator attached to said cover plate and said valve gate for selectively moving said valve gate between said first and second equalizing positions.

21. The removable cover plate assembly as claimed in claim 20 wherein said contact surfaces of said valve seat and valve gate have a flatness tolerance of at least 0.002 inches and a surface finish of at least 32 micro inches.

22. The removable cover plate assembly valve as claimed in claim 20, wherein said central axis of at least one other said second port is coaxially aligned with said central axis of said first port when said cover plate assembly is attached to said valve body.

23. The removable cover plate assembly valve as claimed in claim 20 wherein at least some of said particulate material is wiped away from said contact surface of said valve seat as said contact surface of said valve gate slidingly confronts said contact surface of said valve seat.