Pressure Independent Valve Technology
Each year, building owners across the globe invest millions of dollars into heating and cooling system upgrades in an effort to increase efficiency, reduce costs, and remain green. All too often, however, these upgrades fall short of expectations, and owners are left right back where they were - struggling to improve the environmental friendliness and cost reduction of their operation.
With Pressure Independent Technology (PI), this no longer is the case. Backed by real time energy savings data, PI technology has a proven track record of optimizing heating and cooling systems through dynamically balanced flow control and subsequent improvement of low Delta T problems. Although variable flow pumping systems save building owners thousands of dollars in energy costs every year, complex flow issues caused by pressure fluctuations, system instability, and even minor design flaws can often make it challenging to optimize heating and cooling operations entirely.
For nearly two decades, Belimo’s pressure independent valves have demonstrated a proven ability to mitigate these costly problems through effective flow balancing and advanced control logic. Unlike pressure dependent valves, which suffer flow variation when upstream pressure changes, PI valves maintain precise flow through each coil as commanded by the control signal. As a result, they are unaffected by pressure fluctuations in the hydronic system.
With pressure independent valve technology, only a single valve is required to maintain proper ﬂow through each circuit. There are two types of technology, mechanical and electronic. Mechanical combines a differential pressure regulator with a 2-way control valve to supply a specific flow for each degree of ball opening regardless of system pressure fluctuations. Electronic uses an integrated flow sensor and a robust control algorithm combined with a control valve. The integrated control signal maintains flow set point regardless of system pressure variations with its powerful algorithm that modulates the valve based on its measured true flow.
Valves can arrive from the factory pre-set, so there is no additional balancing needed, or they can arrive set to the full flow position with fast and easy actuator travel adjustment to match the circuit flow. If a facility adds new circuits as a result of expansion, the ﬂow control of existing circuits remains intact – no rebalancing is required.
Figure 1 - Mechanical Pressure Independent Valve Technology
Figure 2 - Electronic Pressure Independent Technology
In addition, because each valve can be selected based on the GPM requirements of the coil, no Cv calculations are required. By precisely controlling the ﬂow, pressure independent valves eliminate the need for balancing valves, thus minimizing any installation and/or balancing costs.
By far, the biggest beneﬁt for the owner comes in the form of energy savings by eliminating overﬂow through the coil, which wastes energy by over pumping and is the leading cause of the low Delta T syndrome in chilled water systems. Belimo pressure independent valves stabilize control of variable ﬂow systems for a lifetime of efﬁciency and worry-free automatic balancing. PI technology can be used to regulate ﬂow through air handlers heating and cooling coils, fan coil units, unit ventilators, and VAV re-heat coils.