Filtration: The UVEX incorporates a hi-flow sand filter, which will remove particles from the tower water to at least 25 micron. The process of sand filtration also removes discoloration from the water resulting in a crystal clear tower / condenser sump. This constant filtration has real cost benefits in terms of the frequency and intensity of clean & chlorination works.
Low energy costs: The UVEX runs constantly but uses very little power. The UVEX 9000 for example draws (typically) around 2.5 A. The main pump is ultra-efficient, the UV is a single 80W amalgam lamp system.
Very low chemical use: The UV unit constantly doses the passing water with intense UV light – a non-intrusive control method where nothing is added to the water – and this accounts for 95% of the work in terms of keeping the cooling tower safe. Combined to this is the secondary circuit, which is a controlled bromine dose. This is programmable but the default is for 6 hours at 2 ppm once a week. We estimate that 1-2 drums of 10 kg bromine only, will be required per year (UVEX 9000 unit).
Very low corrosive load on tower fabric: With carefully controlled weekly dosing there is much less stress on the tower fabric. Quite often chemical systems can be difficult to control. This can mean that the tower itself is attacked by the corrosive action of the chemical, with the result that the life of the tower is reduced. Damaged tower surfaces may also increase levels of microbiological activity. The UVEX dose is once a week and is very precisely controlled by the PLC, which programmes a set of valves to open and close in a sequencing fashion. This gives a very accurate bromine level reading and protects the redox probe from seeing too much bromine. The overall result is that the oxidising effect of the bromine accurately targets the microbiology in the water without compromising the tower.
Fully automatic: the UVEX is the complete water management unit and the PLC/MXD combines functions. For example, the conductivity monitoring for blow down control is combined with the backwash cycle of the sand filter (known as the Bleedclean function). This is an advantage because when water is released to drain to lower the tower mineral concentration, this water is not simply wasted but is used to clean the sand filter, which in turn enables continued optimum filtration. In fact the UVEX requires little manual intervention and can be left to run with remote monitoring (see below), this is of great advantage on sites such as data centres where staffing levels are low.
Data transmission signals available for BMS: The UVEX can be fully monitored remotely. There are 4-20mA signals available for the following: UV intensity; flow through the UV; Conductivity (for blown down) and redox (for bromine level). This means the building management team can observe in real time the water conditions in the tower sump.
Reliable and low maintenance: The new UVEX has been carefully designed to provide long term reliable operation. All components have been selected to further this objective. Also consumable costs are low. Service intervention is limited to: UV lamp change – a 9000 unit has an expected life of 16,000 hours (22 months); sand change in the filter – required after between 1 and 2 years operation; and periodic topping up of the bromine (estimated between 1 and 2 10 kg tubs per year).
Reduced manual Handling and COSHH: Related to the above is the greatly reduced trips to the tower compound to complete chemical top-ups and chemical (residual) tests. COSHH training can also be reduced. In effect, the UVEX will greatly simplify the issues involved in safe cooling tower operation and will free up time in busy maintenance schedules.
