COMMISSIONING | AUTOMATED BALANCING VALVES When valves need a helping hand Do automatic balancing valves mean less need for commissioning engineers? No, says the CSAs Tony Anderson more complexity means intervention is necessary to ensure valves perform as intended C ommissioning a system that contains automated valves should be quick and pain-free for the commissioning engineer, according to most of the sales literature. As most commissioning engineers know, however, this is rarely the case. Over the past 20 years, automated valves have become the frontrunners in the commissioning valve market. CFRs, DPCVs, PICVs and EPICV/EPIVs (see panel for explanation of acronyms) are just a few of the types available, each having their own sophisticated characteristics that can offer huge benefits in hydraulic applications. When installed, using variable-flow pumps with a suitable system flow strategy, automated valves can maximise flow efficiency, greatly reduce operational costs and offer enormous energy savings to end users compared with a traditional fixed-flow system. This translates into significant benefits over the operational lifespan of the system. From the off, its worth noting that the terms automated and self-balancing, as used in sales brochures, largely refer to how the valves operate and control water flow after they have been set up and commissioned. As a specialised component, one of the key challenges with automated valves is getting the system to a commissioned state that allows the valves to perform as per the design intent. Designers should use caution when assigning the pumping strategy around automated valves, to ensure the entire system is maintainable and lends itself to being flushed correctly. There are numerous examples of when temporary bypass loops had to be installed retrospectively around the automated valve or component, because the energy-efficient design model did not allow for suitable flushing and back-flushing of all system components. This is a lengthy and costly addition to each project. It is no coincidence that, in nearly every one of these examples, the commissioning team was not appointed until the hydraulic installations were at an advanced installation level. Specialist care is required when performing the pre-commissioning cleaning of systems that contain automated valves. It is possible that each automated valve has a specific flushing mode or dedicated flushing bypass installed; however, this is rarely found to be the case on site. Constant flow regulators (CFRs) of the removable-cartridge type, for example, will have to have been bypassed or had their cartridges fully removed to achieve flushing velocities. The BSRIA standard flushing velocity or design +10% will not be achievable with the cartridge in place. Careful handling must be undertaken if removing and storing these cartridges, to ensure they are not damaged and are correctly identified and reinstalled in their original location and orientation. Most types of differential pressure control valves (DPCVs) must also be completely isolated during the initial flushing exercise. Alterations made to the system for flushing activities need to be recorded, and the system reinstated to full flow condition before commissioning activities commence. Proving the system has been reinstated, and that control valves and flow cartridges are back in their original positions, is a pivotal verification step on these types of systems. The importance of pre-commissioning cleaning again highlights the benefits of engaging a specialist commissioning engineers perspective at the design stage, as they can offer advice on the installation, chemical cleaning, commissioning and maintenance of these valves and the system as a whole. Small changes, additions or alterations at design stage can make significant operational and maintenance savings in the long term. So, what advantages do automated valves offer to the commissioning of a system? A traditional proportional-balancing exercise on a fixed-flow system over a large circuit could mean revisiting and adjusting individual commissioning valves two or three times. The second and third times are the fine-tuning exercise, Small changes, additions or alterations at design stage can make significant operational savings in the long term TONY ANDERSON is technical manager at the Commissioning Specialists Association 54 October 2023 www.cibsejournal.com