CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is the national stage entry of International Patent Application No. PCT/CN2017/117991, filed on Dec. 22, 2017, the disclosures of which is expressly incorporated herein in its entirety by reference thereto.

TECHNICAL FIELD

The present disclosure relates to a backflow prevention device for medical care purpose and a dialysis apparatus comprising the backflow prevention device.

BACKGROUND

A backflow prevention device is usually disposed between a fluid supply and a connected apparatus for receiving fluid from the fluid supply in order to protect the fluid supply from being contaminated or polluted by the connected apparatus.

Air gap separation method is a common means for preventing a backflow contamination risk. However, the air gap separation method can not be used in some applications, such as a pressurized operation.

In this case, a check valve or double-check valve backflow preventer is a basic form of a backflow prevention device. However, such a backflow preventer is not reliable because the valves may be incompletely closed due to particles or debris in a fluid pipeline; sometime the malfunction of the valves can not be completely avoided, either.

In some important applications, more sophisticated devices with redundancies, such as a reduced-pressure zone (RTZ) device is used. However, most RTZ devices available in the market are mainly produced for a portable water supply and are not suitable for a medical device due to the following reasons:

1) Most RTZ devices have internal flow paths that are not easily disinfected. Such devices have atmospheric vents and test valves that can introduce bacteria into distribution lines. Bacteria can colonize the device and re-contaminate the treated fluid, thereby causing harm to the patient if the device is used in a medical apparatus.

2) Chemical disinfectants may be trapped in the internal flow paths of the conventional RTZ devices during routine disinfection. The trapped disinfectants may then be released into the treated fluid, for example the reverse osmosis water during a dialysis treatment, thereby exposing the patient to a risk of toxicity of the disinfectants.

3) Most RTZ devices are constructed of materials which are not suitable for use with the medical device. Certain metals can contaminate the fluid and present a hazard to the patient.

SUMMARY OF THE DISCLOSURE

In view of the problems existing in the prior art, an object of the present disclosure is to provide an improved backflow prevention device and a dialysis apparatus comprising the backflow prevention device.

For achieving this object, according to a first aspect, provided is a backflow prevention device, comprising: an inlet chamber comprising at least two ports, in which a first port is used for receiving a fluid; a chamber-separating component comprising a separating member and a relief valve; an outlet chamber is separated from the inlet chamber by the separating member; the relief valve being operatively connected with the separating member for opening or closing a drain port of the outlet chamber; wherein the fluid is allowed to be delivered from the outlet chamber only when the relief valve is closed by means of a differential pressure applied on the separating member.

According to an optional embodiment, a second port of the inlet chamber is fluidly connected with a spring-loaded inlet check valve for delivering the fluid flowing across the inlet chamber from the first port.

According to an optional embodiment, the differential pressure is created by the spring-loaded inlet check valve which creates a pressure difference across the separating member when the fluid enters the inlet chamber.

According to an optional embodiment, a second port of the inlet chamber is fluidly connected with a differential pressure generator and an inlet check valve for delivering the fluid flowing across the inlet chamber from the first port.

According to an optional embodiment, the differential pressure is created by the differential pressure generator which creates a pressure difference across the separating member when the fluid enters the inlet chamber.

According to an optional embodiment, the inlet check valve is fluidly connected between the inlet chamber and the outlet chamber to only allow the fluid to flow from the inlet chamber toward the outlet chamber along a forward flowing path of the fluid.

According to an optional embodiment, the backflow prevention device further comprises: an outlet check valve being fluidly connected to the outlet chamber to only allow the fluid to flow through the outlet check valve for delivering the fluid from the outlet chamber, optionally, the outlet check valve being spring-loaded.

According to an optional embodiment, the backflow prevention device further comprises: a drain port cleaning valve for rinsing and/or disinfecting the drain port, which is fluidly connected between the inlet chamber and the outlet chamber in parallel with either a spring-loaded inlet check valve or a combination of an inlet check valve and a differential pressure generator serially connected with the inlet check valve.

According to an optional embodiment, the drain port is used for draining the fluid in the outlet chamber as a backflow prevention measure when there is a leak in an inflow path to the outlet chamber and/or a leak in a delivering flow path from the outlet chamber.

According to an optional embodiment, the separating member is configured as a flexible membrane, optionally, configured with a circular shape.

According to an optional embodiment, the chamber-separating component is supported by a support portion which extends inward radially from a corresponding inner wall of the backflow prevention device.

According to an optional embodiment, the relief valve is configured as a relief valve plunger connected with the separating member to form an integral assembly.

According to an optional embodiment, the assembly is supported by a spring which is supported on a bottom wall of the outlet chamber, optionally, the spring is a coil spring and surrounds the relief valve plunger.

According to an optional embodiment, the backflow prevention device further comprises: an inflow detecting means for detecting a leak in the drain port when there is no fluid consumption delivered in a fourth port from the outlet chamber while there is fluid flowing through an inflow path to the outlet chamber. Optionally, the inflow detecting means comprises a pair of electrodes disposed across an electrically insulated inlet check valve disposed in the inflow path.

According to an optional embodiment, the inlet chamber is configured above the outlet chamber, optionally each chamber is formed in a cylindrical body.

According to an optional embodiment, the outlet chamber has at least two ports, in which a third port is fluidly connected with an outlet of an inlet check valve fluidly disposed between the inlet chamber and the outlet chamber and a fourth port is fluidly connected with an inlet of an outlet check valve for delivering the fluid from the outlet chamber.

According to an optional embodiment, the relief valve plunger has a rod portion and a sealing head portion having a larger diameter compared with the rod portion, optionally, both the rod portion and the sealing head portion are integrated with the separating member and/or molded in one piece.

According to an optional embodiment, the drain port is centrally formed in the bottom wall of the outlet chamber; and/or the drain port is fluidly connected with a funnel drainpipe for air gap separation.

According to an optional embodiment, at least portions of the backflow prevention device contacting the fluid are formed from a biocompatible material.

According to an optional embodiment, the inlet chamber and/or the outlet chamber has a cylindrical cavity whose height is smaller than its radius respectively.

According to a second aspect, provided is a dialysis apparatus comprising the backflow prevention device.

According to the present disclosure, the backflow prevention device has simple structure, reduced dead space and small sizes and can work reliably.

