Understanding Pipe Surface Water Temperature Measurements
This technique uses a 4-channel analog logger with a thermocouple sensor to record long-term water temperature (°F) measurements at one-hour intervals. It measures fluid temperature from the surface of a pipe rather than directly in the water stream. The collected data can be used to determine the cooling load and heat rejected by a cooling plant, the heat load delivered by a heating plant, and the heat recovered by an economizer. For more details on how collected data is used for calculations, refer to the calculation methodology of the system being measured.
Measurements should be taken at one-hour intervals rather than as instantaneous values. When recording hourly measurements, the logger captures multiple temperature readings throughout the hour and stores the average value. Since temperature can fluctuate within an hour, an instantaneous reading may not accurately reflect these variations.
The duration of the long-term measurement should be a minimum of six weeks. Measurements should be taken when the system of interest is operating under normal conditions.
Type of measurement
Measuring pipe surface temperature is a proxy measurement of the fluid temperature.
Measurement Equipment
The measurement equipment needed for this procedure is a 4-channel analog logger that is compatible with thermocouple sensors. Thermocouple sensors are specially designed to measure very high temperatures, such as as those within the flue stack of a boiler, and very low temperatures, such as those on the surface of water pipes for a chiller system. Different thermocouple sensors are used to measure hot or cold pipes.
The contents of this guide are largely based off the following equipment available in the Field Equipment Lending Library:
4-Channel Analog Data Logger equipment
An analog logger that supports up to four external sensors for measuring temperature, current, voltage, air flow, pressure and more in one single logger.
Thermocouple Sensor equipment
Beaded thermocouple probe, teflon-insulated and responsive over a range of -200 to 100℃ (-328 to 212℉) with an initial accuracy of +/- 1.5℃ (+/-2.7℉).
Measurement Procedure
1. Prepare for Data Acquisition
Use the manufacturer’s software to set up and launch the logger(s). Refer to the equipment’s user manual for detailed instructions on how to set up the logger.
- Logging interval: 1-hour4
- Date and time to start logging
- Date and time to stop logging
- Value(s) to measure: Temperature (oF)
- Activate input channels on the logger
- Type of thermocouple sensor (K-type or T-type)
- Sampling interval: 1-second
2. Install Equipment
- Connect the sensors to the data logger.
- Place the data logger near the pipes. Avoid adhering the logger to the pipe itself.
- Clean the surface of the pipe where the sensor will be placed, removing any dust.
- Place the sensor on the clean surface and apply thermal tape to fully cover the sensor.
3. Verify Data is Being Collected
Wait 24-48 hours to verify data collection. Return to the location of the measured equipment and use a laptop or phone with the manufacturer’s proprietary software installed to do the following:
- If necessary, connect the logger to a laptop or phone via USB cable. Otherwise, use the software to connect with the data logger via Bluetooth.
- Analyze the data with a plot graph. This can be done with proprietary software or Microsoft Excel after exporting the dataset as a .csv file.
- Determine whether measured results align with the expected operation of the system or component.
4. Retrieve Measurement Equipment and Download All Final Data
After verifying that the logger is collecting data, do the following:
- Allow the logger to collect data for the remainder of the measurement period.
- After the measurement period has concluded, remove the logger.
- If necessary, connect the logger to a laptop or phone via USB cable. Otherwise, use the software to connect with the logger via Bluetooth.
- Use the proprietary software to stop the logger and end data collection.
- Download all data from the logger and save the file in the.csv file format for analysis.
5. Process and Analyze Measured Data
Use the collected measurement data in the corresponding calculator file based on the type of component you are measuring:
Heat Exchanger
Troubleshooting
This section provides some troubleshooting tips for the most common issues with equipment installation.
Logger measures unexpected values
Verify that the logger is calibrated. Re-calibrate the equipment if necessary. Clean the surface of the pipe with a damp cloth to wipe off any dirt and grime. Ensure the sensor is covered with thermal tape to prevent measurement of the ambient air around the pipe.
