NEWS | PUMPS, VALVES AND PIPEWORK Safe approach Hypochlorous acid offers a safer alternative to biocides for treating water, says Guardian Water Treatments Ian Wedd D uring the lockdowns of 2020 and 2021, Guardian Water Treatment observed a number of large commercial buildings electing to manually run-off traps and outlets to prevent water from stagnating during periods of low occupancy. Even if this is done regularly, it is unlikely to replicate normal water usage in a building designed to host thousands of people. We also saw a significant increase in total viable count (TVC) which gives an estimate of the total concentration of microorganisms failure rates and positive legionella samples compared with the same period pre-Covid. We took more than 30,000 samples from London buildings during the six months from April 2020 (the first full month of lockdown). Most of the buildings in the sample were following manual flushing regimes. Results show a significant increase in failure rates across the board, for both TVC samples and positive legionella results. Comparing the results year on year, data shows the number of out of specification TVC results (water samples that carry unacceptable levels of microbiological contamination) rose by more than 50%. The rate of detection for positive legionella samples also rose by around 20%. While flushing does help prevent stagnation and legionella growth, overall microbiological control is likely to be compromised, which is where measures such as secondary disinfection are so important. Secondary disinfection focuses on maintaining water quality to prevent future issues. Bacteria-killing properties are delivered by biocides such as chlorine, chlorine dioxide and monochloramines. Chlorine dioxide a powerful, selective oxidising biocide, with robust anti-microbial properties is the most commonly used. While it is undoubtedly effective and of particular use in systems where bacteria is already well manifested, it is tricky to maintain its efficiency. Poor storage, fluctuations in flow, exposure to light and temperature differences can severely compromise how well it works. A new approach There is another way that offers considerable benefits in terms of safety, sustainability and cost. Hypochlorous acid (HOCl) is a powerful disinfectant that is 100% safe for humans, chemical-free, non-toxic and naturally occuring. It has been used for more than a century and is commonly found in hospitals as a means of safe disinfection. HOCI has only recently moved over into the watertreatment industry. As well as much-improved safety, it offers benefits in terms of storage and handling. There is no need for PPE and no reduction in quality when stored for a period of time or exposed to sunlight. Environmentally, it has lower CO2 emissions, less wastage and low production costs all in all, the perfect choice for many buildings. Fire fighting boosted by hydrant break tank package set KSB s system uses one main pump to deliver water to above- and below-floor hydrants Pump manufacturer KSB has complemented its portfolio of hydrant break tank package booster sets for fire fighting with its new Hya-Duo D FL-R pressure-booster system. Designed to conform with DIN 14462, the system uses only one main fire-fighting pump to supply hydrants installed above or below floor with up to 192m3 of fire-fighting water per hour. The automatic break tank package booster set is fitted with two fully redundant pumps, each of which has its own power and control circuit. The redundant control systems continuously monitor pressure and limit switches for broken wires and short circuits. Motor and dry-running protection are disabled in the event of fire, ensuring the pumps do not stop before fire fighting has ended. If one of the pumps fails, the redundant control system takes over and starts up the second pump. The Hya-Duo D FL-R can pump 192m3 of fire-fighting water per hour Hevasure develops corrosion monitoring system for Elysator Closed-loop water monitoring specialist Hevasure, working with original equipment manufacturer partner Elysator, has developed real-time monitoring technology for chemical-free closed-water systems. According to Hevasure, its ClearView solution provides technologies that can immediately detect and record deviations in water characteristics that can cause catastrophic corrosion. By using high-purity water of low conductivity, controlling pH, and reducing dissolved oxygen, Elysator can ensure that closed heating and chilled-water systems operate in a healthy condition, without the use of chemicals, delivering stringent water quality in line with the VDI 2035 standard ClearView continuously and remotely tracks these critical parameters, providing confirmation to engineers and managers. Low oxygen conditions without nutrients ensures bacteria cannot survive, and that corrosion is not an issue. 70 October 2022 www.cibsejournal.com CIBSE Oct 22 pp70-71 Pump valve News.indd 70 26/09/2022 15:31