Seasonal Maintenance for Cooling Tower Automation

winter image

Depending on where you are in North America, the seasons are definitely changing. While we are all experiencing shorter daylight hours, some are going from dozens of consecutive days over 100F to highs in the “comfortable” 90’s. Others are waking up to frost and snow on the ground. Already.

The demands on a cooling tower change too, obviously. From an automation perspective, here is a list of items you should attend to:

  • Conductivity sensors: remove and clean the sensor, replace and re-lube the O-rings if needed.
    • Use a soft steel wire brush to gently clean the sensor tips. Avoid copper or brass brushes as they can burnish the tips. Also avoid plastic or nylon brushes as they will leave an organic residue.
    • If necessary, a dilute HCl solution can be used to remove any scale or deposits.
    • Use isopropyl alcohol to remove oil, preferably 90% or higher. Do not use cloths as they often have oils on them, reducing the effectiveness of cleaning. A clean paper towel is a better choice!
    • Perform a calibration.
  • pH and ORP sensors:
    • Clean sensors with dilute HCl to remove scale and isopropyl alcohol to remove any films. Use a Q-Tip to clean the reference junction, solution ground and the glass. Try not to use cloths, as they tend to have oils on them.
    • Keep the sensor wet – remember that if the glass dries out the probe will be ruined and need to be replaced. Store in pH 4 reference solution or probe storage solution.
    • Be sure the probe will not freeze over winter. Remember this is water inside a permeable glass, so if the probe freezes the glass will break and the probe will need to be replaced.
  • Controllers
    • The good news is there is really nothing to be done to lay up the controller. Some data (such as water meter totals) is stored in memory that will be backed up by a capacitor – for 72 hours. The controller settings and program are saved on the e-prom, so that information will not be lost if the power is off to the controller.

A little work now will save you some sensors in the spring!