Liquid Proportional Flow Control

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Liquid Flow Control Challenge

A global leader in the manufacture of innovative modular medical systems (drawing fully on Moore’s Law to set high standards in the evolution of patient care medical equipment, while reducing the physical foot print for ease of deployment) were interested in optimisation and accuracy of fluid control while reducing component size.

An initial project supplying a pneumatic bullet valve for Vacuum relief on an existing system was received with great approval and subsequently led to a new project accurately controlling the flow of a liquid coolant, the challenge being to accurately control liquid flows of up to 20 l/min with less than 0.2bar pressure differential through the valve and zero leakage when in the closed position.


Site visits – problem identification
MAC valve technology was presented to the customer with technical animation explaining the benefits of high shifting forces, balanced design and attributes that lead to extremely high levels of cycling without wear leading to long valve life; a sample case showing the range of bullet valves, fluid valves, proportional pressure and flow controllers.

Concept / Design
The MAC Liquid Bullet Valve Technology coupled with a stepper motor allowed for accurate proportional flow control in a small physically compact design, pressure differential drop within requirements, 3/2way and 2/2way options, precise hysteresis and zero leakage in closed position.

Working as a partnership between the intercompany commercial and development teams the customer’s requirements were taken from approved CAD designs leading to a concept prototype which was produced and tested.  When all criteria was met a specified quantity of units was shipped to the customer for testing within their new Medical prototype system. The time taken from concept to prototype delivered was 7 months.

Testing / Trials
The PFC prototypes were built into the new system where testing was carried out at customer’s premises resulting in physical and operational criteria being met successfully.
A further request during the development was to accurately electronically register the position of the valve from closed to open and the increments in-between to which the MAC valve was happy to accommodate by modifying the stepper motor to include an encoder with closed position switches.

On successful completion of prototype supply, the systems were showcased at a Medical trade fair resulting in a forecast of orders for the customer. MAC valves have approved the prototype for a production unit and PSI Technologies are receiving the customer’s first order after authorisation of the first production run.


The final solution delivered is

  • 3/2 way BV Proportional Liquid Flow controller with Encoder
  • 2/2 way BV Proportional Liquid Flow Controller with Encoder


  • High Accuracy of liquid flow
  • Precise controlling of liquid flow
  • Compact design
  • Competitive advantage over companies producing similar equipment with less accuracy and using outdated technology.

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