Maintenance & Reliability · SOP

Cooling Tower Float Valve Adjustment

Comprehensive procedure for adjusting mechanical float valves on cooling towers, eliminating overflow losses, and performing a makeup water consumption audit to optimize system efficiency.

Estimated Time

45 min

Difficulty

Intermediate

Regulation

CSA Z432

Version

1.0

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Purpose

To provide clear, repeatable instructions for adjusting the float valve assembly on evaporative cooling towers to maintain proper basin water level, prevent overflow waste, and quantify makeup water consumption for efficiency tracking. This procedure reduces water loss, lowers chemical treatment costs, and helps identify leaks or valve degradation before they cause operational problems.

Scope

This SOP applies to all evaporative cooling towers equipped with mechanical float‑operated makeup water valves, including single- and multi-cell arrangements. It covers preventive adjustment, valve seat cleaning, and a standardized makeup water audit using a bucket/stopwatch method or inline flow meter. It does not cover electronic level sensors, variable‑speed makeup pumps, or water treatment chemistry.

Safety Precautions

LOTOLockout/tagout the makeup water supply valve and any electrical disconnect to the cooling tower fan/circulation pump before beginning work.
PPEWear safety glasses, chemical‑resistant gloves, and slip‑resistant boots. Beware of wet decking; apply absorbent granules if necessary.
HAZCooling tower sumps may contain treatment chemicals, biological growth, or hot water. Avoid skin contact; if contact occurs, flush with clean water for 15 minutes.

Required Tools & Materials

Adjustable wrench (10–12 inch)
Flathead screwdriver and wire brush
Pipe wrench for stubborn connections
Bucket (5‑gallon) and stopwatch or calibrated flow meter
Data collection sheet, marking pen, and camera for documentation
Flashlight, mirror for visibility

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Procedure: Step-by-Step

1Isolate & lock out. Close the manual shutoff valve on the makeup water line. Apply personal lockout/tagout per your facility’s procedure. Verify no water flows through the supply pipe.

2Lower the basin level. Open a drain valve or use a bucket/pump to lower the water level to just below the overflow pipe. Do not release water to storm drains without checking local discharge regulations.

3Inspect float valve. Remove the float arm pin (if present). Examine the valve seat, orifice, and float for scale, corrosion, or wear. Clean the seat with a screwdriver and wire brush. Replace the seat washer if pitted.

4Adjust float height. Bend the float arm or turn the adjustment screw so that the valve closes when the water level is 25–50 mm below the overflow pipe. Check the float for buoyancy; replace if cracked or water‑logged.

5Reassemble & refill. Reattach the float arm, open the supply valve slightly, and allow the basin to fill slowly. Watch the valve action — it should seat firmly without chatter or continuous drip.

6Measure makeup flow. With the cooling tower at normal operating load, place a bucket under the makeup line or use an inline flow meter. Measure the volume accumulated over 2–3 minutes. Calculate litres per minute (L/min). Record both pre‑ and post‑adjustment readings.

7Verify level & cycling. Confirm that no overflow is occurring. Cycle the tower fans and pumps through a normal on/off sequence (if possible) to ensure the float valve responds correctly to water level changes.

8Document. Record the date, technician initials, pre‑audit flow, post‑adjustment flow, float condition, and any parts replaced. Attach photos of the valve assembly. Update the preventive maintenance log.

9Remove LOTO & restore service. Remove your personal lockout/tagout, fully open the supply valve, and return the cooling tower to normal operation. Verify that no leaks are present at the valve bonnet or pipe connections.

Cooling Tower Float Valve Adjustment

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