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A Pressure Independent Future


Another good crowd of CIBSE Members & Guests attended the British Hotel, North Adelaide, for the August CIBSE SA Chapter’s presentation on ’A Pressure Independent Future’. Speaker Andrew Brooks from Belimo Actuators, based in New Zealand, spoke with many years’ experience on the difference between pressure independent (PI) and pressure dependent (PD) control valves in Mechanical Services piped systems.

He addressed the comparison of price, the addition of separate balancing valves for PD valves and the PI valves automatically setting the set flow rate regardless of differential pressure changes. 

He talked about the commissioning of both alternate valves and the extra man-power and cost for PD valves. Also, the use of strainers in the system to prevent build-up of dirt and sludge in the control valves.

He went on to discuss Electronic PI valves which give Thermal & Hydraulic feed-back, which are now only viable on larger Air Handling Units. These will be more economic for terminal units within 1 to 5 years as more are manufactured.

He warned about the extra resistance on the systems with flexible pipe connections, suggesting larger pipe size be used, and the use of thermic actuators, due to too slow a reaction time.

A Q&A session completed the evening.

Andrew may be available to talk to other Australian & New Zealand CIBSE Chapters. His talk is directed at Consultants, Contractors and Commissioning Technicians.

Drinks & nibbles where provided in the Bar afterwards by Belimo for the enjoyment of participants and networking.
Ian Small, CIBSE SA Committee.