Dialysis machine with fluid pumping cassette
A dialysis system is disclosed. The example dialysis system includes a housing, a pump actuator housed by the housing, a fluid pumping cassette coupled operably to the housing and including a flexible membrane covering a pump chamber, and a mechanically actuated piston head provided by the pump actuator and positioned to extend towards and away from the fluid pumping cassette. The fluid pumping cassette is positioned such that the flexible membrane of the fluid pumping cassette faces the piston head so that the piston head can push the flexible membrane into the pump chamber of the fluid pumping cassette to expel a fluid from the pump chamber. The example dialysis system also includes a controller programmed to perform a leak test by monitoring a sensed position of the mechanically actuated piston head while the mechanically actuated piston head applies a force to the flexible membrane of the fluid pumping cassette.
1. A dialysis system comprising:
a housing;
a pump actuator housed by the housing;
a fluid pumping cassette coupled operably to the housing and including a flexible membrane covering a pump chamber;
a mechanically actuated piston head provided by the pump actuator and positioned to extend towards and away from the fluid pumping cassette, the fluid pumping cassette positioned such that the flexible membrane of the fluid pumping cassette faces the piston head so that the piston head can push the flexible membrane into the pump chamber of the fluid pumping cassette to expel a fluid from the pump chamber; and
a controller programmed to perform a leak test by monitoring a sensed position of the mechanically actuated piston head while the mechanically actuated piston head applies a force to the flexible membrane of the fluid pumping cassette.
2. The dialysis system of claim 1 , wherein the membrane is moved by the mechanically actuated piston head during the leak test if a leak is present.
3. The dialysis system of claim 1 , wherein the controller is programmed to cause the mechanically actuated piston head to apply a constant force to the flexible membrane of the fluid pumping cassette during the leak test.
4. The dialysis system of claim 1 , which includes a vacuum chamber configured to pull a vacuum on the flexible membrane to open the membrane within the pump chamber to fill the pump chamber with the fluid.
5. The dialysis system of claim 1 , wherein the sensed position of the mechanically actuated piston head is sensed by a sensor that outputs to the controller.
6. The dialysis system of claim 1 , which includes a vacuum chamber configured to pull a vacuum on the flexible membrane to cause the flexible membrane to follow a movement of the mechanically actuated piston head.
7. The dialysis system of claim 6 , wherein at least one of the pump actuator or the mechanically actuated piston head is located within the vacuum chamber.
8. The dialysis system of claim 6 , which includes a valve actuator housed by the housing, and wherein the fluid pumping cassette includes a valve portion in fluid communication with the pump chamber, the valve portion operable with the valve actuator.
9. The dialysis system of claim 8 , wherein the controller is programmed to cause the valve actuator to close the valve portion of the fluid pumping cassette before the leak test begins.
10. The dialysis system of claim 1 , wherein the controller is programmed to trigger an alarm if the sensed position of the mechanically actuated piston head moves outside of an allowable range during the leak test.