Going to New Levels with Old Solutions

Dwyer has a large selection of products that can be used in an equally large variety of applications. Many of these products can be grouped into three main categories: wastewater, building automation, and material handling. A large emphasis of new product development has been concentrated in the building automation market, and the use of cooling towers is a critical component to this industry. Cooling towers act as a heat exchanger to regulate the temperature of the water used in HVAC/R climate control. Because most cooling towers are exposed to ambient air, the potential for evaporation exists; therefore, water levels within the water make-up reservoir are critical and must be monitored and maintained. The water within the reservoir can range from clean to sediment filled, and may contain what can best be described as muck. This muck can become a damaging issue for level sensing equipment.
There are many ways to monitor water level. Dwyer offers four different technologies for water level transmission: submersible, ultrasonic, capacitance, and float.  Using a float transmitter offers continuous level monitoring instead of the point indication that low cost single point float switches provide. However, this technology utilizes moving parts that can wear down over time. To prevent issues caused with moving parts, a capacitance sensor can be used; though, compared to a float transmitter, capacitance technology is offered at a higher cost and can still experience issues, particularly with a sensor coated by impurities or scaling in the reservoir. Ultrasonic transmitters are becoming popular in many specifications due to recent technological advancements that have made ultrasonic sensors more affordable. Unfortunately, in cooling tower applications, the water surface can be turbulent, causing the ultrasonic sound waves to provide inaccurate readings. Set-up can also be time consuming when obtaining the proper transmission for the reservoir depth. Lastly, finding an appropriate mounting location can be complicated for ultrasonic transmitters. Most ultrasonic transmitters have a cone shaped angle and any pipes or cooling rods within the beam angle will cause false readings.
The technology that is the most durable and cost sensible for a cooling tower water reservoir is a submersible transmitter. The Dwyer PBLT2 can be used in clean water or high impurity water applications. The large diaphragm of the PBLT2 was designed to withstand chemical degradation and heavy sludge environments often found in the wastewater industry. Sediment that would hinder other transmitter options has relatively no effect on the efficiency of this sensor. The industrial 316SS design of the PBLT2 offers substantial weight to keep the sensor stationary within a cooling tower reservoir. Even if the PBLT2 were to tip over, the 0.25% full-scale accuracy and consistency of the reading would not be compromised, and the 5 psi standard model is accurate to within 0.4 inches. Installation is also a breeze; simply select the best sensing range, wire to a controller and/or power supply, and lower the sensor into the reservoir. This technology has proven to be very reliable and is one of the lower cost solutions that Dwyer offers. After all, Dwyer’s submersible level transmitters use the same differential pressure sensing technology that we have pioneered since the launch of the Magnehelic® gage. While all transmitters have their niche and can be effective, sometimes the simplest solution is the best.