A systems engineer for a hotel’s water treatment and supply system required an efficient method for monitoring both the level and temperature of water in several storage tanks. The goal was to find a single, robust instrument capable of providing these two distinct measurements as separate analog signals for their control system. The solution was a submersible probe designed for dual-parameter monitoring, which streamlined the installation and provided comprehensive data for process control.
- Application: Continuous level and temperature monitoring in raw, clean, reverse osmosis, and domestic water tanks.
- Challenge: Sourcing a single sensor to provide independent level and temperature outputs to simplify installation.
- Solution: An LMP307T series submersible probe with integrated temperature measurement, providing two 4-20mA signals.
- Integration: The dual outputs connected directly to a Direct Digital Control (DDC) system for combined monitoring.
A customer was engineering a monitoring solution for a hotel’s comprehensive water management system, which included raw water, clean water, reverse osmosis, and domestic water storage tanks. For effective process control and quality assurance, the project required continuous and simultaneous measurement of both the water level and its temperature within each tank. The key technical requirement was to source a single, consolidated sensor that could provide two independent 4-20mA analog output signals, one for level and one for temperature, to be fed into their existing Direct Digital Control (DDC) system. This approach was preferred to simplify wiring and reduce the number of instruments and physical intrusions per tank.
In a hotel’s water management system, monitoring both level and temperature is crucial for operational efficiency, safety, and guest satisfaction. Accurate level measurement is fundamental for supply management, ensuring an uninterrupted water supply for guests and hotel services. It allows for the automated control of pumps to refill tanks when levels are low and prevent costly overflows when they are full. Temperature monitoring is equally critical, primarily for health and safety. Stored water, particularly in large domestic tanks, can create a breeding ground for harmful bacteria like Legionella if the temperature falls within its growth range (typically 20°C to 45°C). Continuous temperature monitoring is a key part of a risk mitigation strategy to ensure stored cold water remains below this threshold. Furthermore, the efficiency of water treatment processes like reverse osmosis is temperature dependent, making this data valuable for optimizing system performance.
The proposed solution was a specialized version of the LMP307T series submersible probe, which integrates a precise temperature sensor alongside its primary hydrostatic pressure-sensing diaphragm. This dual function design perfectly matched the customer’s request for a single-instrument solution. The sensor operates by being lowered to the bottom of the tank, where it measures the water level via hydrostatic pressure while simultaneously measuring the water temperature directly. It outputs these two distinct parameters as separate 2-wire, 4-20mA current loop signals. This feature was critical, as it allowed for a straightforward, industry-standard connection to two separate analog inputs on the DDC controller for individual monitoring and logging.
Using a single, dual-parameter instrument significantly streamlined the installation. It reduced the amount of cabling needed, halved the number of mounting points, and simplified the overall system architecture compared to installing two separate sensors in each tank. The robust 316L stainless steel construction of the probe’s housing and diaphragm ensures long-term reliability and corrosion resistance when immersed in the various types of fresh water. Furthermore, the sensor’s level measurement range was factory-configured to 0 to 4 meters of water column (mH2O) to best suit the 3.3 meter height of the tanks, ensuring optimal signal resolution for both the level and temperature data being sent to the control system.
LMP307T Submersible Dual Level and Temperature Probe
- Level Range: 0 – 4mWG
- Output Signal: 4 – 20mA / 2-wire
- Accuracy: <±0.125% / FS (BFSL)
- Temperature Range: 0 to +70°C
- Output Signal: 4 – 20mA / 2-wire
- Accuracy: 1 °C
- Electrical Connection: Vented PUR Cable
- Housing Material: 316L Stainless Steel
- Seal Material: FKM
- Cable Length (enter in mtrs): 10 metre PUR
- Process Connection: Self flushing nose cone
- Diaphragm Material: 316L Stainless Steel
- Supply Voltage: 9 – 32V dc