Measurement of moisture vapor transfer rate

1. A system comprising:

a test media;

a reservoir containing a fluid;

a conduit between the reservoir and the test media, wherein the conduit is configured to supply the fluid from the reservoir to the test media;

a sensor configured to measure a parameter and obtain a first measurement of the parameter, wherein the parameter is related to an amount of the fluid in the test media; and

a comparator configured to receive the first measurement of the parameter and compare the first measurement of the parameter to a set point of the parameter.

2. The system of claim 1 , further comprising a support surface configured to support the test media.

3. The system of claim 1 , further comprising:

a pump in fluid communication with the reservoir and the conduit, wherein the pump is configured to pump the fluid from the reservoir to the test media at an adjustable flow rate.

4. The system of claim 3 , further comprising:

a driver for the pump, wherein the driver is operable to adjust the adjustable flow rate.

5. The system of claim 4 , wherein the sensor is configured to obtain a second measurement of the parameter after the amount of fluid in the test media is changed, and wherein the second measurement of the parameter is closer in value to the set point of the parameter than is the first measurement of the parameter.

6. The system of claim 1 , further comprising:

a control valve in fluid communication with the conduit, wherein:

the control valve is configured to control a flow rate of the fluid from the reservoir to the test media; and

the sensor is configured to obtain a second measurement of the parameter after the amount of fluid in the test media is changed, and wherein the second measurement of the parameter is closer in value to the set point of the parameter than is the first measurement of the parameter.

7. The system of claim 1 wherein the parameter is electrical conductivity.

8. The system of claim 1 wherein the sensor is an ohm meter.

9. The system of claim 1 wherein the fluid comprises an electrolyte.

10. The system of claim 1 , further comprising a mass on the test media, wherein the mass is configured to simulate a patient load.

11. The system of claim 1 , further comprising a thermal heat supply configured to heat the fluid.

12. A system comprising:

a test media comprising a quantity of a fluid;

a support system configured to support the test media;

a fluid addition system comprising a control system and a supply of the fluid; and

a sensor configured to obtain a first measurement of a parameter of the test media, wherein:

the parameter is related to the quantity of the fluid;

the fluid addition system is configured to add the fluid from the supply to the test media at a fluid addition rate; and

the control system is configured to control the fluid addition rate so that the parameter is maintained at a steady-state value.

13. The system of claim 12 , further comprising an air mover configured to provide a flow of air proximal to the support system.

14. The system of claim 12 , wherein the parameter is electrical conductivity.

15. The system of claim 12 wherein the sensor is an ohm meter.

16. The system of claim 12 wherein the control system comprises a sensor comparator configured to compare a measured value of the parameter to a desired value of the parameter.

17. The system of claim 12 wherein the support system is a low air loss mattress.

18. The system of claim 12 , further comprising a mass on the test media, wherein the mass is configured to simulate a patient load.

19. The system of claim 12 , further comprising a thermal heat supply configured to heat the fluid added from the supply to the test media.

20. The system of claim 12 wherein the fluid addition system further comprises:

a reservoir containing the fluid; and

a pump configured to pump the fluid from the reservoir to the test media.

21. The system of claim 20 wherein the fluid addition rate can be altered by changing an operating parameter of the pump.

22. The system of claim 12 , wherein the control system comprises a control valve and the fluid addition rate can be altered by opening or closing the control valve.

23. The system of claim 12 , wherein the fluid addition system further comprises a reservoir configured to feed the fluid to the test media via gravity feed.

24. A method of measuring a moisture vapor transfer rate, the method comprising:

providing a test media comprising a quantity of moisture;

transferring moisture from the test media at a moisture transfer rate;

measuring a parameter with a sensor to obtain a parameter measurement, wherein the parameter is related to the quantity of moisture comprised by the test media;

adding a fluid to the test media at a flow rate; and

controlling the flow rate so that the flow rate is generally equivalent to the moisture transfer rate.

25. The method of claim 24 , further comprising:

providing an air mover; and

operating the air mover to provide an air flow proximal to the test media.

26. The method of claim 24 , further comprising:

supporting the test media with a support system; and

transferring the moisture from the test media to the support system.

27. The method of claim 24 , further comprising:

comparing the parameter measurement to a set point of the parameter;

controlling the flow; and

obtaining a second parameter measurement that is closer in value to the parameter set point than is the first parameter measurement.

28. The method of claim 24 , wherein the parameter is electrical conductivity.

29. The method of claim 24 , wherein the sensor is an electrical conductivity meter.