Apparatus and method to test for valve leakage in a pump assembly
First Claim
1. A pump assembly having the capacity to self test for leakage, comprising:
- (a) a pumping chamber in which a fluid is pressurized during a pumping cycle;
(b) an inlet valve that periodically interrupts fluid flow into and out of the pumping chamber, with respect to a source of the fluid disposed upstream of the inlet valve;
(c) an outlet valve that periodically interrupts fluid flow into and out of the pumping chamber, with respect to a delivery passage through which pressurized fluid flows when the pump assembly is operating to pump the fluid;
(d) a pressure sensor, disposed downstream of the outlet valve and operative to sense the pressure of the fluid and to produce a signal indicative of that pressure; and
(e) control means for controlling the pumping cycle, including self test means connected to receive the signal produced by the pressure sensor for;
(i) filling the pumping chamber with the fluid;
(ii) closing the inlet and the outlet valves;
(iii) effecting at least a partial pumping cycle to pressurize fluid in the pumping chamber and thereafter terminating the pumping cycle;
(iv) after a predetermined time interval during which the pump assembly is inactive to further pressurize fluid in the pumping chamber, opening the outlet valve; and
(v) determining whether the pump assembly has leaked during the predetermined time interval, as a function of the signal produced by the pressure sensor after the outlet valve is opened.
2 Assignments
0 Petitions
Accused Products
Abstract
Apparatus and method for determining leakage, particularly of valves, in a pumping cassette. A cassette (70) includes a primary valve (34) and a secondary valve (36), which may be selectively activated to control the source of fluid input to the cassette. The cassette also includes an inlet valve (48) and an outlet valve (56) disposed on each side of a pumping chamber (52). Downstream of the outlet valve is disposed a pressure sensor (60) which produces a signal indicative of the pressure of fluid within the cassette at that point. The cassette also includes an air-in-line sensor (40), disposed between a manifold line (38) that connects the primary and secondary valve in fluid communication with an air trap reservoir (44). Leakage in the inlet or outlet valves is detected by closing both valves, pressurizing fluid in the pumping chamber for a predetermined period of time, and then opening the outlet valve. If a pressure pulse having an amplitude less than a predetermined level is detected downstream of the outlet valve when it is opened, either the inlet or outlet valve has leaked. The primary and secondary valves are checked for leakage either by pressurizing fluid in the pumping chamber and checking for retrograde flow of air trapped in the air trap reservoir through the air-in-line sensor, or by pressurizing fluid trapped in the cassette, holding the pressure for a period of time before closing the inlet valve, and then opening the outlet valve to detect a pressure pulse propagating downstream of the outlet valve, using the pressure sensor. If a pressure pulse of less than the predetermined magnitude is detected, one of the primary or secondary outlet valves is leaking. Both tests also detect leakage of other portions of the pumping cassette.
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Citations
27 Claims
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1. A pump assembly having the capacity to self test for leakage, comprising:
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(a) a pumping chamber in which a fluid is pressurized during a pumping cycle; (b) an inlet valve that periodically interrupts fluid flow into and out of the pumping chamber, with respect to a source of the fluid disposed upstream of the inlet valve; (c) an outlet valve that periodically interrupts fluid flow into and out of the pumping chamber, with respect to a delivery passage through which pressurized fluid flows when the pump assembly is operating to pump the fluid; (d) a pressure sensor, disposed downstream of the outlet valve and operative to sense the pressure of the fluid and to produce a signal indicative of that pressure; and (e) control means for controlling the pumping cycle, including self test means connected to receive the signal produced by the pressure sensor for; (i) filling the pumping chamber with the fluid; (ii) closing the inlet and the outlet valves; (iii) effecting at least a partial pumping cycle to pressurize fluid in the pumping chamber and thereafter terminating the pumping cycle; (iv) after a predetermined time interval during which the pump assembly is inactive to further pressurize fluid in the pumping chamber, opening the outlet valve; and (v) determining whether the pump assembly has leaked during the predetermined time interval, as a function of the signal produced by the pressure sensor after the outlet valve is opened. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. In a pump assembly having a plurality of valves, including an inlet valve and an outlet valve, a pumping chamber disposed between the inlet valve and outlet valve, and a control that selectively opens and closes the inlet and outlet valves and activates a driver to pressurize a fluid within the pumping chamber in a pump cycle, apparatus to test for leakage of the pump assembly, comprising:
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pressure sensing means for producing a signal indicative of the pressure of fluid in a fluid passage downstream of the outlet valve; and leak detection means, connected to receive the signal produced by the pressure sensing means, for detecting leakage from the pump assembly as a function of the signal produced by the pressure sensing means immediately after the outlet valve is opened, said outlet valve being opened after fluid within the pumping chamber has been pressurized for an interval of time drain which the driver is inactive to further pressurize fluid in the pumping chamber. - View Dependent Claims (16, 17, 18, 19, 20)
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21. In a pump assembly including an inlet valve, an outlet valve, a chamber in which fluid is pressurized during a pump cycle, a pressure sensor disposed downstream of the outlet valve, and a control for selectively initiating the pump cycle, a method for testing the leak proof integrity of the pump assembly, comprising the steps of:
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(a) filling the chamber with the fluid; (b) closing the inlet and the outlet valves; (c) effecting at least a partial pumping cycle to pressurize fluid in the chamber and then terminating the pumping cycle; (d) after a predetermined time interval during which the pump assembly is inactive to further pressurize fluid in the chamber, opening the outlet valve; and (e) monitoring a fluid pressure downstream of the outlet valve, after it is opened and (f) determining whether the pump assembly has leaked during the predetermined time interval, as a function of said pressure. - View Dependent Claims (22, 23, 24)
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25. A method for testing leakage integrity in a pump cassette including a plurality of valves, comprising the steps of:
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(a) filling the pump cassette with a liquid; (b) closing at least two valves on the pump cassette to define a nominal sealed volume in which liquid is trapped between said valves; (c) effecting operation of the pump to pressurize the liquid trapped in the nominal sealed volume and thereafter stopping the pump to test for leakage; (d) waiting an interval of time during which the pump is not operating to further pressurize the liquid trapped in the nominal sealed volume; (e) opening one of the valves; and (f) detecting that leakage has occurred from the nominal sealed volume defined by the closed valves, as a function of a pressure downstream of said one of the valves after it is opened. - View Dependent Claims (26, 27)
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Specification