Moisture sensing valves and devices

1. An on-demand irrigation system comprising:

a water source;

a valve receiving water from the water source;

a pilot valve controlling operation of the valve and providing on-demand control of the valve, the pilot valve comprising:

a pilot valve inlet in fluid communication with the valve and configured to receive fluid from the valve;

a pilot valve outlet in fluid communication with the valve and configured to direct fluid downstream of the valve;

a pilot valve seat intermediate the pilot valve inlet and the pilot valve outlet;

a pilot valve member biased away from the valve seat to an open position and biased against a closed position; and

a swellable material in operational engagement with the pilot valve member to move the pilot valve member relative to the pilot valve seat between the open position and the closed position;

wherein, when the swellable material is swollen in response to moisture to close the pilot valve, water flow from the pilot valve outlet to the valve is shut off and closes the valve;

wherein, when the swellable material is not swollen such that the pilot valve is in an open position, water flows from the pilot valve outlet to the valve and opens the valve.

2. The on-demand irrigation system of claim 1 , wherein the pilot valve member comprises a plunger.

3. The on-demand irrigation system of claim 1 , wherein the pilot valve member comprises a diaphragm.

4. The on-demand irrigation system of claim 1 , wherein the swellable material contracts in response to a reduction in soil matric potential to a value within the range of about −130 kPa to −90 kPa.

5. The on-demand irrigation system of claim 1 , wherein the swellable material is made of a flexible polyether and rigid polyamide.

6. The on-demand irrigation system of claim 1 , wherein at least a portion of the swellable material is a polyether block amide.

7. The on-demand irrigation system of claim 1 , wherein the swellable material is in a powdered form wherein the particle size is in the range of about 500 microns or less.

8. The on-demand irrigation system of claim 1 , wherein, when heated within a range of 150° C. to 160° C., the swellable material transforms from a powdered state to adhere and form a single, unitary body.

9. The on-demand irrigation system of claim 1 , wherein the pilot valve is downstream of the valve relative to the water source.

10. The on-demand irrigation system of claim 1 , wherein:

the valve comprises a valve inlet, a valve outlet, a pressure chamber, and a valve member being moveable relative to a valve seat to open and close the valve;

the valve inlet being in fluid communication with the pressure chamber.

11. The on-demand irrigation system of claim 1 , wherein:

the valve comprises a valve inlet, a valve outlet, a pressure chamber, and a valve member being moveable relative to a valve seat to open and close the valve;

one side of the valve member facing the valve seat and the other side facing the pressure chamber.

12. The on-demand irrigation system of claim 1 , wherein:

the valve comprises a valve inlet, a valve outlet, a pressure chamber, and a valve member being moveable relative to a valve seat to open and close the valve;

the pilot valve receives fluid from the pressure chamber.

13. The on-demand irrigation system of claim 1 , wherein the valve comprises:

a valve body defining a valve inlet and a valve outlet;

a valve seat intermediate the valve inlet and the valve outlet;

a valve member biased toward the valve seat to a closed position and biased away from an open position;

a pressure chamber defined by the valve body and the valve member; and

an elastic member positioned in the pressure chamber biasing the valve member toward the valve seat to the closed position.

14. The on-demand irrigation system of claim 13 , wherein:

when the swellable material is swollen in response to moisture to close the pilot valve, water flow from the pilot valve outlet to the valve is shut off and pressure in the pressure chamber, coupled with the bias of the elastic member, seats the valve member on the valve seat to close the valve; and

when the swellable material is not swollen such that the pilot valve is in the open position, water flows from the pilot valve outlet to the valve, and pressure in the pressure chamber decreases, such that water from the valve inlet overcomes the bias of the elastic member and moves the valve member away from the valve seat to open the valve.

15. The on-demand irrigation system of claim 1 , wherein the swellable material is in the form of a single, unitary body.

16. The on-demand irrigation system of claim 15 , wherein the single, unitary body is a temporary, intermediate form and the swellable material transforms, at least in part, to a powdered state following exposure to moisture.

17. An on-demand irrigation system comprising:

a water source;

at least one irrigation zone receiving water from the water source, the at least one irrigation zone comprising at least a first irrigation zone;

an irrigation controller controlling at least one control valve, each control valve corresponding to one of the at least one irrigation zones;

a plurality of subzone valves disposed in the first irrigation zone and each irrigating a subzone in the first irrigation zone;

at least one pilot valve in the first irrigation zone controlling operation of each of the subzone valves and providing on-demand control of each of the subzone valves, each pilot valve comprising:

a pilot valve inlet in fluid communication with a corresponding subzone valve and configured to receive fluid from the corresponding subzone valve;

a pilot valve outlet in fluid communication with the corresponding subzone valve and configured to direct fluid downstream of the corresponding subzone valve;

a pilot valve seat intermediate the pilot valve inlet and the pilot valve outlet;

a pilot valve member biased away from the valve seat to an open position and biased against a closed position; and

a swellable material in operational engagement with the pilot valve member to move the pilot valve member relative to the pilot valve seat between the open position and the closed position;

wherein, when the swellable material is swollen in response to moisture to close the pilot valve, water flow from the pilot valve outlet to the corresponding subzone valve is shut off and closes the corresponding subzone valve;

wherein, when the swellable material is not swollen such that the pilot valve is in an open position, water flows from the pilot valve outlet to the corresponding subzone valve and opens the corresponding subzone valve.

18. The on-demand irrigation system of claim 17 , wherein the at least one pilot valve in the first irrigation zone is a single pilot valve disposed in each subzone.

19. The on-demand irrigation system of claim 17 , wherein the at least one pilot valve in the first irrigation zone is a single pilot valve disposed in the first irrigation zone.

20. The on-demand irrigation system of claim 17 , further comprising:

a second irrigation zone receiving water from the water source;

a plurality of subzone valves disposed in the second irrigation zone and each irrigating a subzone in the second irrigation zone;

at least one pilot valve in the second irrigation zone controlling operation of each of the subzone valves and providing on-demand control of each of the subzone valves, each pilot valve in the second irrigation zone comprising:

a pilot valve inlet in fluid communication with a corresponding subzone valve and configured to receive fluid from the corresponding subzone valve;

a pilot valve outlet in fluid communication with the corresponding subzone valve and configured to direct fluid downstream of the corresponding subzone valve;

a pilot valve seat intermediate the pilot valve inlet and the pilot valve outlet;

a pilot valve member biased away from the valve seat to an open position and biased against a closed position; and

a swellable material in operational engagement with the pilot valve member to move the pilot valve member relative to the pilot valve seat between the open position and the closed position;

wherein, when the swellable material is swollen in response to moisture to close the pilot valve, water flow from the pilot valve outlet to the corresponding subzone valve is shut off and closes the corresponding subzone valve;

wherein, when the swellable material is not swollen such that the pilot valve is in an open position, water flows from the pilot valve outlet to the corresponding subzone valve and opens the corresponding subzone valve.