the following detailed description of the invention refers to the accompanying drawings . although the description includes exemplary embodiments , other embodiments are possible , and changes may be made to the embodiments described without departing from the spirit and scope of the invention . wherever possible , the same reference numbers will be used throughout the drawings and the following description to refer to the same and like parts . dimensions of certain of the parts shown in the drawings may have been modified and / or exaggerated for the purposes of clarity or illustration . turning now to the drawings in detail there is illustrated in fig1 the valve 10 of the present invention . the valve includes a body 12 having an inlet 14 and an outlet 16 used to dispense a liquid . located between the inlet and the outlet ports are multiple chambers 18 , 20 and 22 each having an entrance and an exit , such as entrance 24 and exit 26 for chamber 22 . these chambers may take any cross - sectional shape , but typically they are circular holes that extend at a downward angle to the valve body so that fluid can flow down the chambers due to gravity . covering over each of the entrance and exit ports is a tubular elastomeric membrane ( tem ) 28 . the tem is stretched tightly across all of the ports and seals the outlet of the ports preventing product flowing through the chambers . of course in the case of the first chamber 18 the tem does not seal the entrance port . three chambers are present , each sealed tightly against product passage or bacterial ingress . each chamber acts as a “ trap ” against bacteria ingress to the beverage . of course it is to be understood that the invention is not to be limited to three chambers and there may indeed be a different number of chambers . the valve assembly further includes chambers 30 , 32 and 34 that respectively surround the exit port and adjoining entrance port of sequential chambers . thus chamber 30 surrounds exit port of chamber 18 and the entrance port of chamber 20 , chamber 32 surrounds exit port of chamber 20 and entrance port of chamber 22 and chamber 34 surrounds exit port of chamber 22 and the entrance port 36 of outlet 16 . when the tem seals all of the entrance and exit ports no liquid can be dispensed and the valve ensures that no contamination of the liquid can occur . the entrance and exit chambers shall be defined further below . chambers 30 , 32 and 34 are filled with an incompressible fluid . the valve assembly further includes a cylinder 38 that is sealingly engaged by a piston 40 . the cylinder is in fluid communication with chamber 30 . in the closed state the piston is located at the upper end of the cylinder . upon depression air ( or any other fluid ) is caused to be forced out of the cylinder through aperture 42 . this then causes a reduction of pressure in chamber 30 and with a sufficient drop in pressure causes the tem that seals the exit port of chamber 18 and entrance port of chamber 20 to be forced under pressure into chamber 30 . assuming that the tem flexes uniformly this then provides a flow path between the exit port of chamber 18 and the entrance port of chamber 20 . this is best illustrated in fig2 where liquid 44 flows through the flow path 46 defined by the stretched tem 48 caused by the de - pressurising of chamber 30 by flow of air 50 . chamber 30 is in fluid communication with chamber 32 through small aperture 52 , with chamber 32 being in fluid communication with chamber 34 through aperture 54 . the size of apertures 52 and 54 is chosen so that it takes time for the three chambers to achieve equal pressure . this results in the tem covering the ports as discussed above to do so in a progressive manner . thus as illustrated in fig3 where the tem covering the exit port of chamber 20 and entrance port of chamber 22 has just started to expand into chamber 32 causing the fluid flow to progress further . finally as illustrated in fig4 after some time the chambers 30 , 32 and 34 are at an equal pressure causing all of the tem &# 39 ; s to expand into the respective chambers by the same amount enabling liquid 44 to freely flow out of the valve . to close the fluid flow the opposite process is repeated . the piston is moved upwards to pressurise chamber 30 through fluid flow 56 . when the pressure in chamber 30 equals that in chamber 18 the tem starts to collapse closing of the exit port 58 of chamber 18 and entrance port 60 of chamber 20 stopping any further fluid flow . the remaining fluid flows on to the adjoining chambers until all of the tem &# 39 ; s have collapsed when the pressure has been equalised along all chambers 30 , 32 and 34 . the reader can appreciate that operation in fig6 and 7 . hence in operating the valve assembly the operator pushes down on piston 40 , drawing non - compressible fluid behind the piston . the elastic membrane in chamber 30 is drawn open to make up for the reduction in volume that has flown into the cylinder behind the piston . the tem is stretched to a wider diameter and the elastic resistance causes a vacuum in chamber 30 , and resistance to the operator activation of the piston . the diameter of the piston is chosen such that total vacuum could be achieved with low operator activation force . when the piston is fully depressed , an action that may take less then one second , the tem in chamber 30 is strained further than in chambers 32 and 34 . a lower pressure exists in chamber 30 than 32 , and pressure in chamber 32 is less than chamber 34 . this is caused by the pressure drop of the fluid passing through the orifices 52 and 54 . the pressure drop of each orifice causes the desired opening lag of tem in chamber 34 , which lags tem in chamber 32 opening , which lags the opening of the tem chamber 32 . this is desired to ensure when the final product outlet to atmosphere is opened , product flows to preventing bacterial ingress . as illustrated in fig5 , when the piston ( or button ) is held down during dispensing the operator activation force is in equilibrium with the elastic potential energy of the tem &# 39 ; s . pressure in each of the three incompressible fluid chambers 30 , 32 and 34 naturally reaches equilibrium . the tem in each chamber is open the same amount . the volume of fluid displaced by the piston equals the increase in volume of the tem from its diameter growing . the tem is held open purely by the vacuum caused by operator activation force on the piston . product is free to flow through the aseptic tap body , only needing to overcome friction losses associated with tortured path . the product pressure does not need to force open the tem . consequently this can be used as gravity flow valve , not requiring product pressure . to stop the dispensing of the liquid the operator releases activation force on the piston . the tem &# 39 ; s begins to constrict , the constriction changing the volume in the incompressible fluid chamber , consequently drawing up the piston . the fluid is drawn back into each chamber by the constricting tem . the fluid takes longer to be drawn into chamber 34 than chamber 32 , and chamber 32 takes longer to draw the fluid back into the chamber than does chamber 30 . the tem &# 39 ; s cannot close until the all the fluid is drawn back into the chamber , and the piston reaches top of the stroke again . this causes the desired lag time in closing of the tem bacteria traps . the tem in chamber 30 will close first , there being no flow resistance in drawing fluid into chamber 30 . piston 40 is drawn up due to the change in volume of chamber 30 only . whilst that tem is constricting , product flow continues through the other tem &# 39 ; s as these remain open . the next tem will then close , the fluid resistance through orifice 52 causing a lag in closing compared to the tem in chamber 30 . whilst constricting , product flow will be continue exiting the last tem in chamber 34 and the one in chamber 30 has now shut . the tem in chamber 34 will close last , fluid flow through both orifices 52 and 54 causing the greatest lag . whilst constricting , product will continue to flow from the outlet 16 . during the closing sequence of the tem &# 39 ; s , or traps , the purposeful lag in tem trap closings causes a continual flow of product from the outlet . this product outflow prevents bacterial ingress , and is why the sequential trap closing is desired . a biasing means , such as a spring ( not shown ) may be located so to act on the piston to push it up therefore forcing the elastomer to close via force transfer through fluid to the elastomeric membrane . the reader will now appreciate the advantages of the present invention including the following : 1 . opening and closing the valve manually whilst maintaining sterility . 2 . hydraulically operating to open , close and sequentially , in predefined order , operate the valve ports to maintain positive pressure at all times of operation , effectively decreasing the probability even further of contamination into the stored liquid . 3 . manually achieve what the hydraulically operating system achieves . this is a variation of design using similar concept as the hydraulic design . 4 . including in certain applications a breather for the basic valve can be incorporated with the basic valve so that it can filter air through to the dispensing container to replace fluid or liquid loss as a result of dispensing . 5 . gravity and high pressure dispensing from a collapsible container and even dispensing from a semi - rigid containers such as pet bottles with a basic valve having a sterile air filter incorporated . the basic valve can also vary in shape . shapes such as cylindrical , cone or horseshoe and others that are not described here . in another variation of the invention , the channels can be made totally on the surface , between the valve body and the elastomeric membrane . the number of channels could be at least one or more in number . the elastomeric membrane can either be stuck by heat to the valve , glued or simply remain in place by the force against the valve . the valve body and elastomeric membrane can be made from any suitable material or make use of antimicrobial plastics or other materials or new materials which contain antimicrobial constituents embedded . in another variation of the invention , the valve can have more than one liquid entry channel . for example , in one inlet channel , liquid flows and by valve / tap rotation , the liquid flow is stopped and the second inlet fluid or gas , used to disinfect and remove liquid residues can pass through to clean the valve body . in a further variation to the invention the piston may be biased by a mechanical means , such as a spring . without a spring , the total vacuum in pressure to open the tubular membrane may be limited to a small amount . with a spring the hydraulic liquid can be pressurised by greater than atmospheric pressure . whilst not limiting the invention to any particular measurements it is expected that a sealing pressure of some 30 kpa will be applied and that an operator driven piston may provide up to − 90 kpa of pressure . as to the dimensions of the valve , the valve body can be typically iomm diameter and the tem a 0 . 18 mm silicon membrane . it is also to be understood that it is not intended to limit the invention to the embodiment described above . thus the following may be variations on the concept that is the intention of the present application . the valve body ( plastic body with elastomeric membrane on the outside ), may be mechanically operable . in a circular shape it will have a rotary concept within the smaller inner circle that will press the elastomeric membrane shut against the valve body when the rotary tap is turned to the left ( one way rotation ). this works by having half the rotary tap able to press the elastomeric membrane shut against the same sequence described in the hydraulic version . when the tap is again rotated in the one direction , the mechanical impingement of the elastomeric membrane will lift since half of the tap will not impose any pressure on the elastomeric membrane . a multiple of spring biasing means may be employed as briefly described above . the valve body can be of differing size and shape and have any number of internal channels and surface “ traps ”, that is tem &# 39 ; s located within a dedicated chamber . there can also be a version of the valve that will not have a peristaltic opening / closing motion . in this variation , a mechanical impingement of flow or an on / off system may be included to operate the flow of the valve . the valve body does not necessarily require channels and all flows can be directed between the valve surface and elastomeric membrane , the channels could be one in number to as many as required . in another version of the invention , there may be the option to add a “ breather ” passage from outside to the inlet should . the breather can filter and sterilise air going back into a pet bottle after squeezing liquid out of the bottle . the breather can help restore or replace the missing volume in such a pet bottle . illustrated in fig8 and 9 is a second embodiment of the present invention . here the aseptic valve is prevented from opening by applying a pressure on the membrane 28 ( pouch ). the valve manifold 62 supports a locking spout 64 that is slidable along the longitudinal axis of the manifold . the sealing sleeve or membrane 66 sheaths the manifold 62 and is held in place by retaining rings 68 . the locking spout includes sealing rings or protrusions 70 dimensioned so that when the valve is in the closed position they abut the membrane 66 at the inlets and outlets of the various flow channels 74 thus mechanically preventing fluid from flowing through the valve channels . when the locking spout 64 is slid down as shown in fig9 ( although the direction is not important ) the sealing rings 70 move to then abut the sleeve 66 against the valve manifold body allowing the sealing sleeve to expand into the cavity 72 defined between the spout and the manifold and thus allowing fluid to flow through the channels in the manifold and out through the outlet port 76 fig1 to 14 illustrate a similar embodiment as to fig8 and 9 but where the mechanical operation is achieved by a rotatable action rather then a longitudinal motion . thus the locking spout 64 includes longitudinal sealing protrusions 78 that can be rotated into position to mechanically seal the inlets 80 and the outlets 82 . when rotated out of position as illustrated in fig1 , the sealing sleeve can move into the cavity 72 as shown in fig1 . the embodiments in fig8 to 14 illustrate three flow channels . it is however to be understood that there may be less or more flow channels and that the invention is not limited to a particular number . in addition these further embodiments illustrate the mechanical sealing of the various inlets and outlets . it should be understood that in some circumstances one inlet or outlet may indeed be mechanically sealed . other times there could be a plurality . thus the present invention is not to be understood as limiting the invention to all inlet and outlets having to be sealed . in a further embodiment , not shown , the arrangement of mechanically sealing of the various inlets and outlets may be achieved in a progressive manner . typically one would first seal the uppermost outlet and then progressively seal the others . this would ensure that any fluid has sufficient time to flow out of the valve manifold so that it does not remain in it and be subject to contamination . this progressive sealing may be achieved by staggering the sealing ring 68 or sealing protrusions 78 so that if the locking spout 64 is slid or rotated the uppermost inlets and outlets would be sealed first . further advantages and improvements may very well be made to the present invention without deviating from its scope . although the invention has been shown and described in what is conceived to be the most practical and preferred embodiment , it is recognized that departures may be made therefrom within the scope and spirit of the invention , which is not to be limited to the details disclosed herein but is to be accorded the full scope of the claims so as to embrace any and all equivalent devices and apparatus . in any claims that follow and in the summary of the invention , except where the context requires otherwise due to express language or necessary implication , the word “ comprising ” is used in the sense of “ including ”, i . e . the features specified may be associated with further features in various embodiments of the invention .