Abstract:
The invention pertains to a hygienic vacuum valve for use in sterile environments such as food processing, medical and pharmaceutical applications where a vacuum valve is advantageously utilized in situ on processing equipment to eliminate multiple vacuum lines and valves remotely located from the processing equipment. The novel evacuation valve and method for evacuating, providing a sterilized environment and then sealing the package is accomplished by utilizing a vacuum valve having a housing which accommodates a first piston for opening and closing a vacuum inlet ported to a vacuum outlet and a second piston disposed between the housing and the vacuum outlet for rapidly releasing the vacuum after the package has been sealed. The first and second pistons each preferably include a sealing head which seats in a tapered frusto-conical shaped seat for positively sealing the vacuum inlet and the vent port in the operation of the valve.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application benefits from the filing date of an earlier filed provisional application Ser. No. 60/162,134 filed Oct. 29, 1999. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention pertains to a hygienic evacuation valve, typically employed in food industry, pharmaceutical or medical processing equipment. The novel hygienic evacuation valve includes a first piston cylinder combination for positively opening and closing a vacuum source which is ported in the housing to an evacuation port in combination with a second piston cylinder combination for rapidly releasing the vacuum after the packaging machine has sealed the product. Optionally, a special gassing or sterilization port may be providing along with a positive pressure release to assist in the release of the sealed package. The optional special gassing or the provision for a sterilized environment for the packaged product can be provided by a gassing port associated with the housing of the novel hygienic evacuation valve. 
     The novel hygienic evacuation valve includes a housing with a first piston having a sealing head for sealing a vacuum fitting having a tapered seat for receiving the sealing head of the first piston and a second piston, the second piston also having a sealing head for seating in a tapered seat in the novel evacuation valve in which the first piston and second piston are pneumatically controlled to operate sequentially to first close the vent port and then open the vacuum inlet to the vacuum outlet of the housing to provide evacuation of a product on a product processing machine and then, once evacuated, close the first piston and open the second piston to rapidly release the vacuum in the valve and the line to the product processing machine after sealing of the product. The rapid release of vacuum from the valve and the line to the packaged product as well as the option to provide positive pressure after closing the vacuum line assists in removing the sealed product from the product processing machine. 
     The novel evacuation valve further includes ports for providing special gas environments or the sterilization of packaged products by the introduction of specialized gasses into the product to be packaged to provide either a sterilized or a special gas environment for the packaged product. After providing a special gas environment or sterilization the vent port valve piston is closed and the evacuation piston is opened to remove some, if not all, the special gas from the inside of the package prior to sealing and then reopening the vent port valve piston to rapidly remove vacuum pressure to assist in the separation of the sealed and packaged product. In the preferred application of the novel evacuation valve, the wall or walls of the packaged product are collapsed around the package as is common in the vacuum packaging of cheese and dairy products in sealed thin film plastic packages. 
     Optionally, the novel evacuation valve may be adapted and operated to first evacuate a product to be packaged by first closing the vent port valve, then opening the evacuation piston to evacuate the package and then opening the special sterilization or gassing port to admit a special sterilization or processing gas to the package before sealing the package. Once the package is sealed the vent port is opened to release the vacuum in the line to the packaged product. In such applications, the packaged product is generally placed in sealed containers Which have one or more non-deformable walls such as are utilized in the packaging of cheese, meats and the packaging of some medical devices. 
     The novel evacuation valve includes flanges for connecting the vacuum inlet fitting to the housing, as well as a flange for connecting the vacuum outlet to the product processing machine and a further flange for connecting the first cylinder housing to the evacuation valve. An optional fourth flange can be provided for connecting the vent valve or gassing ports to the novel hygienic evacuation valve housing. The purpose of utilizing flanges in the preferred application of the invention is to provide a seamless, non-threaded, smooth stainless steel valve for processing packaged products requiring a clean, hygienic, sterile or sanitary environment. 
     The novel method of the invention provides for the hygienic and sanitary packaging of products requiring a partially or substantially completely evacuated package or a package containing a specialized gassed, sterilized or treated ambient environment prior to the sealing of the packaged product. The method provides for the treatment of the product in the package by the introduction of various sterilizing fluids or specialized gasses into the product before the sealing of the product package before the sealing of the package and subsequent release of the vacuum to the packaged product and release of the packaged and sealed product from the processing machine. 
     The advantages of the novel evacuation valve and method include the ability to place the novel hygienic evacuation valve in situ on the package processing machine as a result of the compact size of the novel evacuation valve. The novel evacuation valve further allows a single port to the packaged product to accomplish a multiplicity of functions including gassing, evacuating and venting in a single line as opposed to the requirement in the prior art of multiple lines to the packaged product. Further the novel evacuation valve positively opens and closes the vacuum and positively controls ventilation by the utilization of the first and second pistons and eliminates the necessity of remotely mounting the valve with respect to the processing machine and requiring the inefficient application of vacuum to the packaging machine by requiring vacuum hoses and a multiplicity of other hoses to run from the remotely located vacuum valve to the packaging machine. 
     2. Description of Related Art, Including Information Disclosed Under 37 C,F.R, 1.97 and 1.98 
     The prior art includes various types of vacuum valves employed in a variety of different machines and packaging applications. A few of the vacuum valves include various types of ports and systems for relieving vacuum pressure once the vacuum has been removed from the source. Some of these valves include threads and various types of vacuum fittings, which are generally not compatible with applications involving medical, pharmaceutical and food processing applications, which require an evacuation valve without seams or threads in which food or processed products can collect to contaminate the contents of the sanitary packaged material. Hygienic evacuation valves typically used in the food processing art, are commonly remotely located from the food processing machine as a result of their size and the complexity of their components. Typically, such remotely located valves require the connection of long vacuum hoses from the remotely located valve to the packaging machine, which reduces the efficiency of the evacuation process. 
     Further, such vacuum valves, due to their size and complexity, require an amount of space that is incompatible with locating the valve on the product processing and packaging machines. Typical prior art vacuum valves used in the food processing and pharmaceutical processing industries for hygienically packaging food products includes the Tiament valve manufactured by the Tiament Company at Im Rutter in D-35216 Biedenkopf Wallau, Germany. This valve is typically remotely located in a housing separate from the packaging machine and typically takes up a space of about 12 inches by 6 inches and includes hoses that connect the valve to the hygienic packaging machine. 
     Unlike available evacuation valves used in the food processing industry, the present valve is of a compact design, employs a positive control over both the vacuum inlet piston and vacuum vent piston and can be disposed directly on the hygienic packaging machinery. Further, unlike the available prior art the novel evacuation valve is designed to utilize a single port to not only evacuate but also to gas-purge and release pressure in the line, valve housing and port. In addition as a result of its compact size the novel valve allows the more efficient utilization of vacuum along with the more positive control over the vacuum, utilizing pistons having a cylindrical sealing head, in combination with a frustro-conical or tapered valve seat to positively control the opening and closing of the vacuum, as well as the opening and closing of the venting ports. 
     Other prior art uncovered in a patent search, includes Woods U.S. Pat. No. 4,221,101, which illustrates generally the type of packaging machines and processes utilized for sealing a food product such as cheese and bacon. As illustrated in FIG. 7, a pair of tubes are employed to provide for gassing and evacuation from a remotely located evacuation valve. The invention, unlike the prior art, allows the novel evacuation valve to be disposed in situ on the packaging machine as a result of its compact size and utilizes a single tube to provide evacuation, gassing and the release of pressure in the tube and valve housing. 
     Prior art valves uncovered in the search also include “two-in-one” pressure and vacuum relief vent devices as represented by Zenkich U.S. Pat. No. 5,479,978. These prior art valves, like the novel evacuation valve of the invention, utilize a single port in the container wall to supply vacuum and pressure release. Unlike the present invention, such prior art does not provide positive control over both vacuum and pressure relief, provide three in one capabilities and are not designed for medical pharmaceutical and food processing applications. 
     Beck U.S. Pat. No. 5,564,457 provides a vacuum breaker valve configured for clean in place applications in the food and dairy processing industry. The vacuum breaker valve of Beck U.S. Pat. No. 5,564,457 is, however, not used for vacuum packaging, but instead provides for the entry of air into the valve body upon the depressurization of fluid to prevent a siphoning effect upon a fluid (liquid) in the passageway or conduit. The only features shared by Beck U.S. Pat. No. 5,564,457 and the invention are the ease of cleaning the valve and the valve&#39;s application to the food processing industry. 
     SUMMARY OF THE INVENTION 
     The invention pertains to a novel evacuation valve for use in pharmaceutical, medical and food processing applications having a single outlet port for gassing, evacuation and pressure release utilizing positive control over a first piston or vacuum, piston for opening and closing a vacuum port to a packaged product and positive control over a second piston or vent piston after the packaging or sealing of the package to rapidly release the vacuum to assist in the rapid release of an evacuated and sealed package from the packaging machine. 
     The novel compact evacuation valve eliminates problems of prior art packaging valves by providing a seamless, non-threaded valve assembly preferably made of stainless steel or other materials and alloys suitable for the sterile and hygienic handling of food, medical and pharmaceutical materials. The novel evacuation valve assembly includes a main valve body or housing, a piston activating chamber and a vacuum inlet assembly which are connected together with flange clamps. The utilization of flange clamps assists in the cleaning and maintenance of the valve in a sanitary and hygienic condition and allows for easy removal, cleaning and sterilization of the components. 
     As a consequence of its compact design, the novel valve not only can be attached in situ or directly on the packaging and filling machines, but also, the novel evacuation valve utilizes vacuum more efficiently allowing orifice sizes to be reduced as much as ⅓ the size of orifices on comparable vacuum valves. The compact nature of the design, as well as its positive control over vacuum and venting and optional specialized gassing or sterilization processing of packages allows the novel evacuation valve to be utilized in accordance with the method of the invention, which provides for attaching the novel valve directly to the product packaging machine, instead of requiring remote location of the novel evacuation valve, as has heretofore been utilized in the prior art. 
     The novel evacuation valve includes a main housing for accommodating a first piston having a sealing head for positively opening and closing a vacuum inlet connected to a vacuum outlet port in the housing. A second piston, disposed intermediate the vacuum outlet and a vent valve, operates to open and close the vent to the vacuum outlet. The operation of the first piston and the second piston to open and close the vacuum and vent ports are controlled by a solenoid. In operation, when the first piston is closed, the second piston opens the vent to the vacuum outlet and when the first piston is open the second piston closes the vent. The first and second pistons, preferably include a sealing head designed to seat in a tapered opening to provide positive control over vacuum and venting operations. 
     The first and second pistons are preferably pneumatically operated, which, together with the shape of the piston sealing head, in combination with the tapered seats, provide a rapid and positive control over the vacuum and venting operations. The positive control over vacuum, venting and gassing is provided by utilizing a piston with a tapered seat. This arrangement is further augmented by disposing the tapered seat intermediate the piston sealing head and the housing with the tapered seat tapering toward the area of greatest vacuum or least pressure. 
     An optional product gassing or sterilization processing port is provided in the valve housing to gas or provide for the sterilization of the product in the package before it is sealed. The optional gassing or sterilization port can also be opened and closed with a pneumatically controlled piston. Typically in food and pharmaceutical industries, a gas is introduced into the product package before the product is evacuated and sealed. The novel processing port can introduce nitrogen as is typically used in the food processing industry, or an inert gas or other processing or sterilization gas into the packaged product. Once gassing is complete the vent port is closed, the evacuation port opened by the activation of the vacuum piston to remove excess nitrogen, inert gas, or other processing gas introduced into the packaged product. Upon completion of evacuation, the first piston or vacuum piston is closed and the venting piston or second piston is opened. Optionally, the venting piston can be connected either to the ambient environment or to a positive pressure source to provide a positive pressure for assisting in the release of the sealed packaged product. 
     The novel evacuation valve of the invention, as a result of its compact size and configuration, is easily cleaned on the machine, easily disassembled for maintenance or sterillzation for use in various pharmaceutical, medical and food and dairy products applications. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The advantages of the invention will become more apparent to those skilled in the art in conjunction with the detailed description of the invention in which: 
     FIG. 1, FIGS. 1A,  1 B and  1 C are exploded views of the novel evacuation valve with FIGS. 1A,  1 B and  1 C enlarged views of FIG. 1; 
     FIG. 2 is a top plan view of the novel evacuation valve housing with the internal parts removed; 
     FIG. 3 is a front elevational view of the novel evacuation valve housing of FIG. 2; 
     FIG. 4 is a right side elevational view of the novel evacuation valve housing of FIG. 2; 
     FIG. 5 is a side elevational view illustrating the cylinder housing of the novel evacuation valve of FIG. 1; 
     FIG. 6 is a bottom plan view of the cylinder housing of FIG. 5; 
     FIG. 7 is a cross-sectional view of FIG. 6, taken along the lines  7 — 7  of FIG. 6; 
     FIG. 8 is a perspective view illustrating the piston sealing heads utilized in combination with the tapered seats in the novel evacuation valve; 
     FIG. 9 is a side view of FIG. 8; 
     FIG. 10 is a side view of an alternative embodiment of the sealing head illustrating a tape red sealing head; 
     FIG. 11 is a perspective view of an alternative embodiment of a sealing piston head; 
     FIG. 12 is an elevational view of a further embodiment of a sealing piston head and tapered seat combination; 
     FIG. 13 is a schematic view of a further embodiment of the novel evacuation valve utilizing an optional pneumatically activated gassing piston; 
     FIG. 14 is a schematic view of an alternative embodiment of the novel evacuation valve; 
     FIG. 15 is a schematic view of a prior art package and evacuation system; 
     FIG. 16 is a schematic view of a package and evacuation system of the invention; and 
     FIG. 17 is a side elevational view illustrating an application of the novel evacuation valve in situ on a packaging machine. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Evacuation valves constructed in accordance with the preferred embodiment of the invention, employ a housing having a single outlet line to a packaging machine along with a first piston, preferably pneumatically operated to open and close a vacuum inlet and a second piston to open and close a vent valve, wherein the first piston and second piston are designed to operate so that when the first piston is closed the second piston is opened to provide venting through the single outlet line and when the first piston is open, the vent piston is closed to provide evacuation through the single outlet line of the housing. An optional gassing port and an optional gassing piston and seat can also be provided. 
     Preferably, the first and second pistons are disposed substantially perpendicular to one another in the housing and connected to the single outlet line and the optional product gassing or sterilization port is provided for providing a modified atmosphere packaging or medium for the packaged product before the packaged product is partially or completely evacuated and the vacuum in the housing and line to the packaged product is either rapidly removed or a positive pressure is provided to assist in the removal of the packaged product from the packaging and sealing machine. Typically, such evacuation valves demand the valve be easily cleaned, provide a positive control over vacuum and the rapid release of the vacuum after the sealing of the package. Such evacuation valves have no perceptible leakage and operate at a vacuum of about 29.4 inches of mercury to about 1 Torr as well as providing positive control over the vacuum and the release of vacuum in the valve housing. 
     Referring now to FIGS. 1,  1 A,  1 B and  1 C, a novel evacuation valve  10  is illustrated in accordance with the best mode of the invention. The evacuation valve  10  includes a housing  12  and a combination gassing, venting and evacuation port  14  (FIG.  1 A), which provides vacuum to the packaging machine chamber for the package (FIG. 17) and which is designed for easy connection directly to an evacuation nozzle of a packaging machine (FIGS. 16 and 17) through a flange clamp  16 , which connects flange  18  of housing  12  to a matching flange on the line to the evacuation nozzle of the packaging machine. 
     An O-ring  20  is provided for sealing flange  18  to a corresponding evacuation flange on the packaging machine to provide a vacuum tight seal. Flange clamp  16  is preferably a tri clover flange clamp and is available from various venders including Tri-Clover of Kenosha, Wis. and Top Line Process Equipment Corp. Of Bradford, Pa. Flange clamp  16  preferably is made in two halves pivotably attached to each other and secured through a threaded bolt  22  for adjustably securing flange clamp  16  to flange  18  of housing  12  to provide a vacuum-tight seal. 
     Referring now to FIGS. 1,  1 A,  2  and  3 , housing  12  includes a vent collar  24  (FIG. 1A) which provides venting to the packaging machine chamber (FIG. 17) and which includes a plurality of vent openings  26  to allow a rapid release of vacuum from housing  12  to assist in the release of an evacuated packaged product. It will be recognized that vent openings  26  may be vented to the atmosphere or positive pressure ports may be provided to positively provide positive pressure to assist in the rapid removal of vacuum in housing  12  and the line to the evacuation nozzle of the packaging machine. 
     Vent collar  24  includes a plurality of threaded openings  28  for receiving a plurality of bolts  30  for securing a cylinder end plate  32  and spacer  34  through which vent piston  36  is operated in spacer  34  and vent collar  24  which forms a chamber  38  (FIG. 2) in which vent piston  36  operates. Chamber  38  terminates in an inwardly tapering sealing seat  40  which receives the sealing head  42  of piston  36 . Vent piston  36  is designed to mate with the inwardly tapering sealing seat  40  to form an airtight seal by utilizing a cylindrical sealing head  42  which is composed of rubber or an elastomeric material that is attached to vent piston  36  by screw  44  through washers  46  and  48 . 
     Cylinder end plate  32  includes a bushing  50  and an O-ring seat for seating O-ring  52 , which is closed by washer  54  and nut  56 . Bolt  58  provides for adjustment for the travel of piston  36  in chamber  38  and provides for the adjustment for the seating and sealing of cylindrical sealing head  42  in inwardly tapering sealing seat  40 . A first pneumatic fitting  60  introduces air pressure into the top of a piston activation chamber to advance vent piston  36  to close the vent by forcing the cylindrical sealing head  42  into the inwardly tapering sealing seat  40 . A second pneumatic fitting  62  is provided to introduce air pressure into the bottom of the piston activating chamber to rapidly retract vent piston  36  from the inwardly tapering sealing seat  40  and allow the venting of vacuum from the interior of housing  12  and evacuation port  14  through vent openings  26 . The advancement and retraction of vent piston  36  and the piston activation chamber is similar to the advancement and retraction of the vacuum valve piston as will be described hereinafter in greater detail in reference to FIG.  1 B. 
     Referring now to FIGS. 1 and 1B, housing  12  includes a cylinder housing flange  64 , with a tapered support plate  66 , which includes a pneumatic port  68 , connected to pneumatic fitting  70  for activating vacuum valve piston  72 . A sealing gasket  74  is utilized for providing for the sealing of the cylinder housing  76  to housing flange  64  with flange clamp  78  that engages cylindrical housing flange  64  on housing  12  to flange  80  on cylinder housing  76 . A bushing  82  is utilized in opening  84  in plate  66  for guiding vacuum valve piston  72  in housing  12 . A bolt  86  is threadably received in opening  88  of vacuum valve piston  72  and provides support for upper cylinder cup  90  and lower cylinder cup  92 , which are secured to vacuum valve piston  72  through washers  94 ,  96  and  98  and bushings  100  and  102 . A threaded bushing  104  is disposed through cylinder housing  76  to provide adjustment for vacuum piston  72  in housing  12  in a manner similar to that described with respect to vent piston  36 . Threaded bushing  104  is connected to adjustment bolt  105  through O-ring  106 , washer  108  and locking nut  110 , in a manner similar to adjustment bolt  55  for vent piston  36 . 
     Referring now to FIGS. 1,  1 A,  1 C and  4 , the other end of vacuum valve piston  72  is connected to cylindrical sealing head  112 , through washers  114  and  116  and through bolt  118 , which is threadably engaged into a threaded opening  89  in vacuum valve piston  72 . O-rings  120  and  122  are provided for sealably engaging the sides of vacuum valve piston  72  and are captured in O-ring recesses  124  and  126 , respectively in housing  12  (FIG.  4 ). A vacuum fitting  128 , having a flange  130 , is secured to housing  12  by flange clamp  132  which simultaneously engages flange  134  on housing  12 . 
     A gasket seal  136  is designed to provide an air-tight seal between vacuum valve fitting  128  and vacuum valve fitting flange  134 . Vacuum valve fitting  128  includes barbed grooves  137  for accommodating a vacuum hose inlet. Vacuum valve fitting  130  includes an inwardly tapering sealing seat  140  for receiving cylindrical sealing head  112  to positively seal the vacuum source port  142  from housing  12  by the activation of vacuum valve piston  72 . Vacuum valve piston  72  is positively controlled by fluid and preferably pneumatic air pressure introduced into pneumatic fitting  70 , which transports the air pressure through port  68  to lower cylindrical cup  92 , which forms a seal between the cylinder cup  92  and the inner wall of cylindrical housing  76 , thereby forcing the retraction of vacuum valve piston  72  from inwardly,tapering sealing seat  140  to admit vacuum into housing. 12  and into evacuation port  14 . 
     After evacuation and sealing vacuum valve piston  72  is advanced to close vacuum source port  142  by introducing air pressure into cylinder housing  76  through fitting  144  to provide positive air pressure upon upper cylinder cup  90  to force vacuum valve piston  72  and cylindrical sealing head  112  down into inwardly.tapering sealing seat  140  of vacuum valve fitting  130  to positively control the admission of vacuum into housing  12  and out through vacuum evacuation port  14 . Once vacuum source port  142  is closed, vent piston  36  is retracted by admitting air pressure through fitting  62  to remove cylindrical sealing head  42  from inwardly tapering sealing seat  40  to rapidly release vacuum pressure from evacuation port  14  and housing  12  through vent openings  26 . 
     Referring now to FIG.  1  and FIG. 4, an optional sterilization or gassing port  146 , which provides the gas inlet port to the packaging machine chamber (FIG. 17) and can be provided in housing  12  to introduce special gases to packaged products through evacuation port  14 . Port  146 , in housing  12 , includes a fitting  148  that is connected to a fluid reservoir for introducing a special processing gas used to prolong the freshness or enhance the flavors of food products through modified atmosphere packaging techniques as are known to those skilled in the art. These processing gasses are introduced into housing  12  and through evacuation port  14  into a package in a packaging machine attached to evacuation port  14 . In such applications of the invention, an optional fluid, such as nitrogen, may be introduced through port  146  and through evacuation port  14  into the packaged product to provide gassing, sterilization or other in situ processing in the packaged product. Thereafter, vacuum valve piston  72  can be opened to remove excess gas, such as nitrogen, from the packaged product and the product is then sealed. Vacuum valve piston  72  is then closed to close the vacuum inlet and vent piston  36  is opened to release the vacuum from housing  12  and evacuation port  14  to allow the sealed product to be removed from the processing and packaging machine. 
     Referring now to FIG.  8  and FIG. 9, the preferred configuration of the cylindrical sealing head  42  and  112  is illustrated, which, for the purposes of illustration will be described with respect to cylindrical sealing head  112 . Cylindrical sealing head  112  is of a cylindrical cross-sectional configuration having an opening  150  for receiving and connecting bolt  118  to vacuum valve piston  72 . In the preferred embodiment of the invention, the cylindrical sealing head is not tapered and is designed to mate with the inwardly tapering sealing seat  140  in the vacuum fitting  128  and inwardly tapering sealing seat  40  of housing  12 . Substantially cylindrical sealing head  112  is preferably composed of rubber or an elastomeric material that in combination with the smooth inwardly tapering metal wall of sealing seat  40  or  140  provides an airtight seal. 
     In an alternative embodiment of the invention, a modified cylindrical seal  112 , can include tapered edges  152  for conforming to the inwardly tapering walls of the sealing seat  140  to assist in reducing wear on the cylindrical seal as illustrated in FIG.  10 . In a further embodiment of the invention as illustrated in FIG. 11, a modified piston  150  is illustrated having a metal head  152  with a groove  154  for receiving a rubber or elastomeric O-ring  156  for providing a seal in inwardly tapering sealing seat  40  or  140 . 
     Referring now to FIG. 12, an alternative embodiment of a piston and sealing seat is illustrated, wherein a modified. vacuum valve piston or vent piston  160 , in housing  12  is designed to close upon an inwardly tapering rubber seal  162  and press the rubber seal against the inwardly tapering walls  164  in modified housing  12 . Piston  160  may include one or more O-ring seals  166  disposed around the end of the piston to assist in the sealing operation. 
     Referring now to FIG. 13 a modified evacuation valve constructed in accordance with an alternative embodiment of the invention is illustrated. The evacuation valve  170  includes a housing  12  having vent openings  26 , a vent piston  36  with a sealing head  42  for mating with an inwardly tapering sealing seat  40 . A single evacuation port  14  serves to provide evacuation gassing and pressure release to a packaging machine. A cylinder housing  76  is provided for activating a vacuum valve piston  72  having a sealing head  112 . Sealing head  112  is designed to seat in tapered seat  180  to close modified vacuum port  182  which provides vacuum to evacuation port  14  through housing  12 . Vacuum valve piston  72  is activated in cylinder housing  76  by air pressure through fitting  144  on cup  90  to open the evacuation valve and air pressure through port  184  to provide pressure on cup  92  to close the evacuation valve. 
     An optional positively controlled gas piston  186  having a sealing head  188  is designed to fit in tapered seat  190  to open and close the admission of an optional gas such as nitrogen into housing  12  and out evacuation port  114 . Optional positively controlled gas piston  186  includes an air cylinder  76  for activating piston  186  in a manner as similarly described with respect to vacuum piston  72 . Flanges  192  are provided at each of the ports to assist in mounting and interconnecting all the components to provide an easily cleanable evacuation valve. 
     Referring now to FIG. 14 a further embodiment is illustrated having a modified housing  200 , a vacuum valve piston  72 , a modified vacuum port  182  and an air cylinder  76  with air cylinder cups  90  and  92  for the activation of vacuum valve piston  72 . A vent piston  36  along with vent holes are disposed in housing  200  to provide venting to housing  200  and evacuation port  14  in a manner similarly described with respect to FIG.  13 . An optional gassing port  204  is provided to supply a purge gas to a package as previously described with respect to FIG.  1 . 
     As discussed, the novel evacuation valve of the invention is of a compact configuration, provides positive control over fluids, is easily cleaned and can be placed in situ on a packaging machine. The prior art (FIG. 15) generally employs a remotely located valve  210 , a vacuum source  212  and a modified atmosphere gas  214 . The vacuum valve  210  generally controls a separate vacuum line  216  and a separate modified atmosphere gas line requiring at least two lines to package  220 . The invention in contrast (FIG. 16) employs a novel evacuation valve having a single special gassing, vent and evacuation port  14  to supply all the necessary gases to package  220 . 
     In further contrast to the prior art the novel evacuation valve  10  can be located in situ on a packaging machine  230  as illustrated in FIG.  17 . The novel evacuation valve  10  is operated by a solenoid  232  to not only evacuate package  220 , but also supply modified atmosphere gas and provide for the rapid release of vacuum through the single evacuation port  14  as heretofore described. 
     The novel evacuation valve in operation provides positive control over both the opening and closing of the vacuum source as well as the opening and closing of the venting port to the evacuation port. The compact nature of the novel evacuation valve allows is to be placed directly upon food packaging machinery and provides for the efficient and rapid evacuation and rapid removal of vacuum in product processing machinery by the positive control over a first piston disposed between the housing and a vacuum source and a second piston disposed between the housing and the vacuum outlet. 
     The positive control over both the first and second pistons allows for the evacuation and quick removal of vacuum pressure from various packaging and processing operations as are used in the medical, pharmaceutical and food processing industries. The novel valve further is preferably is made of stainless steel or other material that can be quickly and easily disassembled and cleaned for sanitary and hygienic processing operations. 
     As will be recognized by those skilled in the art, the invention has a wide range of applicability to various types of processing and packaging machines, where vacuum packaging of products is employed. In addition, optional in situ processing operations can be accomplished by the provision of optional sterilization and processing ports in the novel evacuation valve. Further, those skilled in the art can make numerous changes and substitutions to the invention by modifying the pistons and sealing heads to accommodate specific applications. These changes and modifications are deemed within the level of those of ordinary skill and are included within the scope of the following claims. 
     As used herein and in the following claims, the word ‘comprising’ or ‘comprises’ is used in its American technical sense to mean the enumerated elements include but do not exclude additional elements which may or may not be specifically included in the dependent claims. It will be understood such additions, whether or not included in the dependent claims, are modifications that both can be made within the scope of the invention. It will be appreciated that these and other modifications can be made within the scope of the invention as defined in the following claims.