Water quality sensors and Urban.io temperature probes, installed and supported in the UKCooling tower monitoring
Keep the cooling water in control between the weekly checks.
Sensors in the circulating water track conductivity, pH, oxidising biocide and temperature around the clock. When a reading drifts out of its range, the people who look after the tower hear about it the same day, and the checks HSG274 asks for carry on as normal.
- Conductivity
- pH
- Oxidising biocide
- Temperature
- Precision dosing
WeeklyHSG274 cooling water checks
QuarterlyMinimum legionella sampling
Every 10 minTemperature readings
Why watch the water
A cooling tower can drift out of control between two weekly checks.
HSE guidance asks for weekly checks of the cooling water and legionella sampling at least every quarter. Between those checks the water keeps changing, with every hot afternoon, every pause in dosing and every bleed that does not open.
1992
Sites must notify their local authority of a cooling tower or evaporative condenser, under regulations made in 1992.
Weekly
HSG274 Part 1 lists conductivity, pH, oxidising biocide and microbial activity as weekly checks for cooling water.
Source: HSE, HSG274 Part 1, Table 1.9
Quarterly
Routine monitoring for legionella in a cooling system should be done at least quarterly.
Source: HSE, HSG274 Part 1, para 1.133
20 to 45 °C
The water temperature range HSE describes as suitable for legionella growth.
Source: HSE, Legionnaires’ disease
How it works
The sensors read the same water your weekly checks sample.
pH, conductivity and oxidising biocide sensors sit on the circulating water, and an Urban.io temperature probe reports the water temperature every 10 minutes. Readings go to one dashboard, with alarms for each limit.
We review the system.
We look at the tower, the existing controls and the checks your water treatment contractor runs, and choose the sensors.
Sensors read the circulating water.
pH, conductivity and a free chlorine or ORP sensor for oxidising biocide sit on the circuit, with a temperature probe on the return.
Dosing can be metered precisely.
A MAC liquid dosing valve can add biocide or inhibitor in measured doses where precise dosing is needed.
Alarms reach the treatment team.
Out of range readings raise an email or SMS to the site and to your water treatment contractor.
What you see
A stopped dosing pump shows up as a reserve that keeps falling.
While dosing runs, the biocide reserve rises and falls inside its range. If the dosing stops or the drum runs dry, the reserve keeps dropping, and the alarm fires on the day it happens instead of at the next weekly check.
- Upper and lower limits for each reading
- Conductivity trend between bleeds
- Temperature on the return water
- History kept for your records
HSG274 checks
The sensors watch the water between the tests your contractor runs.
Some checks in HSG274 Part 1 can be read continuously. Others stay as dip slide and laboratory tests. Continuous readings do not replace those tests. They show what the water did in between.
| Conductivity | Weekly check. HSE notes it is often used to set the bleed level. | SPS-EC sensor |
|---|---|---|
| pH | Weekly check. It affects scaling, corrosion and how well biocides work. | SPS-pH sensor |
| Oxidising biocide | Weekly check of the biocide reserve. | SPS-CI-C sensor or SPS-ORP sensor |
| Microbial activity | Weekly check, conventionally with dip slides. | Stays a dip slide or laboratory test |
| Legionella | At least quarterly. | Stays a laboratory test |
Frequencies from HSG274 Part 1, Table 1.9 and paragraph 1.133. Read more about the weeks between legionella results.
Alerts
The water treatment contractor hears about it the same day.
A biocide reserve that falls on a Monday can be fixed on a Monday. You choose who hears about each limit: the site engineer, the person responsible for legionella control, the contractor or all three.
Notify.
An email or SMS reaches the people you name when a reading leaves its range.
Correct.
The alarm names the tower and the reading, so the dosing or the bleed can be checked straight away.
Record.
Every reading is stored and can be exported, alongside your manual checks and laboratory results.
Tower eventsExample feed
Example feed for illustration. Locations, times and values are not real data.
Where it fits
It suits any site that runs an evaporative cooling system.
Cooling towers and evaporative condensers serve hospitals, data centres, factories and large buildings, and every one of them needs the same control of its water.
Hospitals
Cooling plant serving wards and theatres, where water hygiene records matter most.
Data centres
Evaporative cooling that runs all year, where downtime is not an option.
Manufacturing
Process cooling where scale and corrosion cost output as well as safety.
Food and drink
Plants with refrigeration and cooling loads that peak in the summer.
Large commercial buildings
Rooftop towers on offices and shopping centres in the middle of busy towns.
Energy and utility sites
Cooling water on plant that has to keep running through every season.
Water treatment contractors
Service teams who look after towers on many client sites and want to see every one of them between visits.
Not sure which readings you need?
Tell us about the tower and your current treatment programme. We will suggest what is worth reading continuously.
Why AQUAIOT
We plan, install and support the whole system.
The sensors come from specialist manufacturing partners. AQUAIOT selects them for your tower, installs them, connects them and stays with you after go-live.
System review
We look at the tower, the controls and the treatment programme, and plan the sensor points.
Installation
Sensors go on the circulating water and the return, and dosing valves where they are needed.
Dashboard and alarms
We set the limits for each reading with you and your contractor, and choose who hears what.
Training and support
Your team learns the dashboard, and we support the system for as long as it runs.
A water quality probe, left, and the Urban.io temperature probe sensor, right.
The products
Water quality sensors report the chemistry continuously.
The same sensors AQUAIOT uses for water quality monitoring read pH, conductivity, ORP and free chlorine. An iSPS-X instrument carries up to four sensors at one point and reports them together.
- pH and conductivity
- Free chlorine or ORP
- Up to four sensors per iSPS-X
- Urban.io temperature probes
- RS485 Modbus on site
- Cellular or LoRaWAN telemetry
Questions
These are the questions duty holders ask first.
Do the sensors replace dip slides and legionella sampling?
No. HSG274 Part 1 still asks for weekly microbial checks and legionella sampling at least quarterly, and those stay as dip slide and laboratory tests. The sensors show what the water does between them.
Which readings can be continuous?
Conductivity, pH, oxidising biocide as free chlorine or ORP, and the water temperature can all be read continuously and sent to the dashboard.
Can it work alongside our existing water treatment controller?
Yes. The sensors can run alongside the controller you have. Where an existing instrument already gives a 4-20 mA signal, an Urban.io Process Loop Sensor wired in series with it can report that reading too.
Who receives the alarms?
You choose. Alarms can go to the site engineers, the person responsible for legionella control, your water treatment contractor or all of them, by email or SMS.
Do we still need to notify the council about our cooling tower?
Yes. The Notification of Cooling Towers and Evaporative Condensers Regulations 1992 require the local authority to be notified, and monitoring does not change that duty.
Can the readings support our records?
Every reading is stored and can be exported, which gives your records a continuous history alongside the manual checks and laboratory results.
Speak to an expert
Tell us about your cooling system and we will plan the monitoring.
An AQUAIOT engineer will look at the tower, the treatment programme and the checks you run today, and at who needs to hear when a reading drifts.
- System reviewWe check the tower and its controls before anything is ordered.
- Installation and commissioningSensors fitted, connected and tested on site.
- One monitoring partnerCooling water alongside your Legionella and water quality monitoring.
Prefer to talk? Call 02392 233611 or email info@aquaiot.co.uk.
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