초록 ▼

A water valve assembly includes a valve body having defined therein (i) an inlet, (ii) an outlet, (iii) a central cavity, and (iv) a component access opening, wherein fluid advancing into the valve body through the inlet must pass through the central cavity before exiting out of the valve body throu

A water valve assembly includes a valve body having defined therein (i) an inlet, (ii) an outlet, (iii) a central cavity, and (iv) a component access opening, wherein fluid advancing into the valve body through the inlet must pass through the central cavity before exiting out of the valve body through the outlet, and further wherein the component access opening is configured so that a valve component may be advanced into the central cavity through the component access opening. The water valve assembly further includes a retaining bracket having a retaining portion positioned in relation to the valve body so as to block advancement of the valve component from the central cavity to a location outside of the valve body through the component access opening.

대표청구항 ▼

A water valve assembly includes a valve body having defined therein (i) an inlet, (ii) an outlet, (iii) a central cavity, and (iv) a component access opening, wherein fluid advancing into the valve body through the inlet must pass through the central cavity before exiting out of the valve body throu

A water valve assembly includes a valve body having defined therein (i) an inlet, (ii) an outlet, (iii) a central cavity, and (iv) a component access opening, wherein fluid advancing into the valve body through the inlet must pass through the central cavity before exiting out of the valve body through the outlet, and further wherein the component access opening is configured so that a valve component may be advanced into the central cavity through the component access opening. The water valve assembly further includes a retaining bracket having a retaining portion positioned in relation to the valve body so as to block advancement of the valve component from the central cavity to a location outside of the valve body through the component access opening. circuit, and wherein the method further comprises the steps of: (a) detecting a back pressure of the air being injected into the open downstream air duct with the pressure sensor; and (b) correlating the back pressure of the air with the fluid's position at the various stopping points. 7. The method of claim 6, comprising the further step of: (c) opening or closing the air ducts based on the position of the fluid within the circuit to generate and release pneumatic barriers thereby stopping and starting fluid flow at desired stopping points within the circuit. 8. The method of claim 1, wherein at least one said air duct is in communication with a fixed volume bladder configured to expand to contain air displaced by advancing fluid, and wherein after said bladder has expanded to said fixed volume essentially no further air flow occurs in said air duct, causing a pneumatic pressure barrier to be generated within said microchannel. 9. The method of claim 1, further comprising the steps of: (a) opening the at least one upstream air duct to allow the fluid to advance in said at least one microchannel until the fluid reaches and covers the at least one upstream air duct, which strengthens the pneumatic barrier and prevents fluid flow beyond the at least one upstream stopping point; and (b) opening at least one downstream air duct, to allow the fluid to advance within said at least one microchannel to the stopping point proximate to and downstream of said downstream air duct. 10. The method of claim 1, wherein the microfluidic circuit further comprises at least one sensor for detecting the position of the fluid in the circuit, and wherein the method further comprises the steps of: (a) detecting the position of the fluid in the circuit with the sensor; and (b) selectively opening or closing the air ducts based upon the position of the fluid in order to control fluid flow within the circuit. 11. The method of claim 10, wherein fluid flow within said microchannel is stopped by closing an air duct. 12. The method of claim 10, wherein the at least one sensor is an optical sensor for detecting the presence of fluid. 13. The method of claim 10, wherein the at least one sensor is located at the fluid inlet to detect back pressure in the fluid. 14. The method of claim 13, further comprising the steps of: (a) monitoring the back pressure of the fluid introduced into the microfluidic circuit; (b) determining the fluid's position based upon the monitored back pressure; and (c) opening or closing the air ducts based on the fluid's position within the circuit to generate and release pneumatic barriers thereby controlling fluid flow within the circuit. 15. The method of claim 10, wherein fluid flow within said microchannel is started by opening an air duct. 16. The method of claim 10, wherein said fluid circuit comprises a branch microchannel connecting to said at least one microchannel upstream of at least one said air duct, and wherein fluid flow is diverted from said at least one microchannel into said branch microchannel by closing at least one said air duct to generate a pneumatic pressure barrier in said at least one microchannel. 17. A method of controlling fluid flow in a microfluidic circuit, comprising the steps of: (a) providing a microfluidic circuit comprising an inlet, at least one microchannel, and at least one air duct communicating with said at least one microchannel, wherein said microfluidic circuit is initially filled with air; (b) introducing fluid into said microfluidic circuit under pressure via said inlet; (c) causing fluid to advance in said microchannel upstream of one said air duct while permitting air downstream of the advancing fluid to flow out of said microchannel via said air duct; and (d) subsequently preventing the flow of air out of said microchannel via said air duct, thereby generating a pneumatic pressure barrier in said microchannel opposing advancement of fluid in said micr ochannel. 18. The method of claim 17, wherein air flow out of said microchannel via said air duct is prevented by blocking the flow of air through said air duct. 19. The method of claim 17, wherein air flow out of said microchannel via said air duct is prevented by introducing pressurized air into said air duct. 20. The method of claim 18, wherein said microfluidic circuit comprises a second microchannel branching from said at least one microchannel upstream of said air duct, wherein said pneumatic pressure barrier causes fluid flow to be diverted from said at least one microchannel into said second microchannel. 21. The method of claim 17, comprising the further step of: (a) Permitting the flow of air out of said microchannel via at least one air duct, thereby releasing said pneumatic pressure barrier in said microchannel and permitting advancement of fluid in said microchannel. 22. The method of claim 21, wherein said step of permitting flow of air out of said microchannel is performed by opening an air duct downstream of the air duct used to generate said pneumatic pressure barrier. 23. The method of claim 17, comprising the additional step of: (a) Determining the location of fluid advancing in said microchannel; and (b) Performing the step of preventing flow of air out of said microchannel via said air duct as a function of the arrival of fluid at a selected location in said microchannel. 24. The method of claim 21, comprising the additional step of: (a) Determining the location of fluid advancing in said microchannel; and (b) Performing the step of permitting flow of air out of said microchannel via said air duct as a function of the arrival of fluid at a selected location in said microchannel. 25. A microfluidic circuit comprising: a substrate having at least one channel for fluid flow and having at least one air duct connecting to said at least one channel at a first connection point, herein said at least one channel is initially filled with air that is displaced by advancing fluid; and at least one stopping point proximate to and downstream of said First connection point where the flow of fluid advancing in said at least one channel from upstream of said first connection point can be at least temporarily slopped by a controllable pneumatic pressure barrier; wherein said at least one air duct is configured to permit the escape of said air displaced by said advancing fluid from an air column within said channel while said fluid is upstream of said first connection, and wherein said at least one air duct is configured to prevent the escape of air from said air column when said fluid has advanced past said first connection point. 26. The microfluidic circuit of claim 25, wherein one air duct is in communication with each of the at least one stopping points within the circuit. 27. The microfluidic circuit of claim 25, wherein at least one said air duct further comprises a swellable material adapted to swell upon contact with fluid to reduce or block fluid flow in said air duct. 28. The microfluidic circuit of claim 27, wherein said swellable material comprises a hydrogel material. 29. The microfluidic circuit of claim 25, wherein at least one said air duct further comprises a capillary barrier adapted to prevent fluid from entering the air duct. 30. The microfluidic circuit of claim 25, wherein said pneumatic pressure barrier is formed when fluid flow in said at least one channel is opposed by air trapped within said air column downstream of said fluid, and wherein said pneumatic pressure barrier may be removed by releasing the air within said air column. 31. The microfluidic circuit of claim 30, wherein said air is released through at least one downstream air duct connecting to said at least one channel at a second connection point downstream of said first connection point. 32. The microfluidic circuit of claim 31, wherein said at least one downstream air duct is configured such that said air is r