The first step is to contact a CTI LTA like McHale. Once you pride basic information about your tower that includes:
- Air Inlet Dimensions
- Riser material, diameter and if Pitot taps are installed.
- Voltage and horsepower of the Fans
The Primary Measurements for this test include
Water Flow
Water flow measurements are typically made using an elliptical pitot tube measured on each riser. Pitot ports are generally installed based on the riser diameter with 10 pipe diameters upstream and 5 pipe diameters downstream. Alternate measurement locations and methods can be discussed to meet operational requirements. When Pitot taps are not available, alternative measurements such as ultrasonic flow meters and Dye Dilution may be utilized.
There are three (3) major water temperature measurements required for thermal testing.
- Hot Water Temperature– Typically measured using a high-accuracy resistive thermal detector (RTD) in a flowing well.
- Cold Water Temperature – Typically measured using a high accuracy RTD in a flowing well located at the discharge side of each operating circulating water pump.
- Makeup Water Temperature– Makeup water temperature is only required if the makeup flow crosses the test boundary
Inlet Air Temperatures
The primary measurement is the entering air wet bulb temperature. This measurement is made using a high-accuracy RTD installed in a psychrometer with a cotton continuously water-wetted wick installed on the end of the RTD. Air is drawn across the surface of the wick and the wet bulb temperature is measured and continuously recorded by the remote data acquisition system. These sensors are distributed at the inlet face of the cooling tower in an equal area grid in a set minimum number based on CTI ATC 105, Appendix G.
Fan Power
Fan power is generally measured at the fan control module. This is generally a three (3) phase power measurement that is made by a trained electrician utilizing all required safety equipment. This measurement is made once per test and corrected for line losses between the measurement point and the fan.
Wind Speed & Direction
Wind speed and direction are secondary measurements used to determine stability. Testing in high wind can reduce performance and lead to the recirculation of the hot moist exhaust air into the inlet.
Barometric Pressure
Barometric pressure may be measured with a meteorological grade barometer accurate to within 0.03 KPa (0.1 inHg).
Circulating Water Samples
Samples of the circulating water may be taken from the tower’s hot water inlet during the test. This sample is used to determine if there are any questions concerning the condition of the circulating water; if so, the sample shall be analyzed by a reputable testing laboratory to determine conformance with Paragraph 2.3 of CTI ATC 105-2022.