Dialysis machine valve: proportional and on/off solutions for medical OEMs

A dialysis machine valve has to dose, switch and isolate fluids with total repeatability, treatment after treatment. Dolphin Fluidics designs valves for dialysis equipment around a patented shape memory alloy (SMA) actuator instead of a solenoid: silent operation, power consumption up to 20 times lower and closed-loop control built into the valve.

Below you will find four valves for dialysis systems, each with its technical data, and a guide to choosing the right one for your circuit.

On this page:

• Precision Valves for Dialysis Machines
  
  • Digipinch Valve – no contact with the fluid
  • Digimed Valve – two independent channels, ISO 10993 materials
  • Smart HP Liquid Valve – the widest pressure range, up to 20 bar
  • On/Off Valve – simple switching, 10 times lighter
• How to choose a dialysis machine valve
• SMA vs solenoid: 4 parameters that change in a dialysis machine
• Materials, hygiene and compliance
• Custom valves built around your dialysis machine
• FAQ

Precision Valves for Dialysis Machines

Each valve below is normally closed, runs on 5–24 VDC and can be customized for your device. The difference is in how it touches the fluid, how many channels it controls and what pressure it handles.

Digipinch Valve – no contact with the fluid

The Digipinch Valve is a normally closed pinch valve with on/off and proportional closed-loop control. Its shape memory actuator proportionally controls the force applied to the tube carrying the liquid, and therefore the flow. The valve never touches the fluid, which makes it the cleanest option for lines where sterility comes first.

• Flow regulated by proportional control of the force on the tube
• No drift: stable and accurate over time
• Totally silent operation
• 32-bit microprocessor with integrated memory and customizable control firmware
• Hardware interface for external pressure, flow or temperature sensors, to close the loop on the physical quantity you need

Digimed Valve – two independent channels, ISO 10993 materials

The Digimed Valve is a 2-way, normally closed, full-separation valve with two independent channels for the proportional control of liquid, air or gas. It was designed specifically for healthcare: all its materials conform to ISO 10993. One device can manage two media at once, reducing the number of components on the board.

• Two separate channels with barbed ends for soft tubes
• Full-seal gasket for a perfect seal and a high level of hygiene
• Totally silent operation, power consumption up to 20 times lower than conventional solenoid valves
• 32-bit microprocessor with built-in memory and customizable control firmware
• Direct interface with external pressure, flow or temperature sensors

Smart HP Liquid Valve – the widest pressure range, up to 20 bar

The Smart HP Liquid Valve is a 2-way, normally closed valve with on/off and proportional closed-loop control, built to dose and dispense liquids with high precision and no drift, even under high pressure. Of the four valves on this page, it covers the widest pressure range.

• Full-seal gasket for a perfect seal and a high level of hygiene
• Quick-connect cartridge integrated in the valve
• Totally silent operation, power consumption up to 20 times lower than traditional solenoid valves
• 32-bit microprocessor with built-in memory and customizable control firmware
• Hardware interface for external sensors to close the control loop

On/Off Valve – simple switching, 10 times lighter

The On/Off Valve is a 2-way, medium-separated, normally closed valve for dispensing and mixing. It is the choice when the circuit needs a reliable open/close function rather than proportional regulation: 10 times lighter and with an actuator that uses 20 times less power than existing valves.

• On/off control with end-of-stroke control
• Reliable sealing system with medium separation
• Noiseless operation
• Patented design
• NSF/FDA material compliance

How to choose a dialysis machine valve

Choose by function first, then by pressure and interface. The table matches the most common requirements to the right Dolphin valve.

Two questions help narrow the choice further:

• Do you need to regulate flow or just switch it? Regulation calls for one of the types of proportional valves (Digipinch, Digimed, Smart HP Liquid). Switching calls for the On/Off Valve.
• Can the fluid touch the valve? If it cannot, the Digipinch works on the tube from the outside. If it can, full medium separation in the Digimed and Smart HP Liquid keeps the fluid path apart from the electronics.

SMA vs solenoid: 4 parameters that change in a dialysis machine

Switching from solenoid to SMA actuation cuts power, noise and components at the same time. A proportional SMA valve is not a solenoid valve with a different coil: it is a different actuation technology, and in a dialysis machine the difference shows up on four parameters.

For machine designers this means fewer components in the BOM, less heat inside the enclosure and a quieter device, which matters most when treatment happens near the patient for hours. For a deeper technical analysis, read our proportional valve vs solenoid valve comparison.

Materials, hygiene and compliance

When you qualify a dialysis machine valve, the first question is what touches the fluid. This is what Dolphin declares for each valve:

• Digimed Valve: all materials conform to ISO 10993; full-seal gasket.
• On/Off Valve: NSF/FDA material compliance; medium separation.
• Smart HP Liquid Valve: full-seal gasket ensuring a perfect seal and high hygiene.
• Digipinch Valve: no contact with the liquid, which flows only inside the tube.

Body materials, seals and fluidic connections can be adapted to your application as part of a custom project. To receive the material documentation for a specific valve, send us your project requirements.

Custom valves built around your dialysis machine

You do not have to design your circuit around a catalog valve. Every Dolphin valve can be customized to the functional requirements of your machine:

• Electronic and mechanical interface: connectors, fluidic ports, mounting
• Fluidic performance: pressure range and flow
• Control electronics and firmware: control algorithm and communication protocol (Analog, PWM, RS-485, I2C)
• IoT integration: data exchange with the host system

Dolphin Fluidics is powered by Fluid-o-Tech and brings 70 years of experience in fluidics and 25 in smart actuators. Share pressure, flow, media and interface requirements, and start defining the valve configuration for your dialysis system with our engineers.

FAQ

What types of valves are used in a dialysis machine?

Dialysis machines combine on/off valves for switching and proportional valves for regulating flow and pressure. Pinch valves are used where the fluid runs in a tube and must not touch the valve. Dolphin covers all three with the On/Off, Smart HP Liquid, Digimed and Digipinch valves.

Can an SMA proportional valve replace a solenoid valve in a dialysis machine?

Yes, when the application fits its pressure and flow range. An SMA valve uses up to 20 times less power, works silently and integrates closed-loop control, so it does not need an external controller.

Which Dolphin dialysis machine valve never touches the fluid?

The Digipinch Valve. It regulates flow by applying a controlled force to the tube, so the liquid stays inside the tube and never contacts the valve.