Monitoring Lift Stations: A Guide to Reliable Level Sensing

Lift stations are an essential component of municipal water and wastewater systems. Keeping them in operation and performing properly is absolutely vital. Monitoring pumps and liquid levels are constant tasks that keep operations running smoothly in lift stations. This is where industrial level sensors are needed.

Sewer lift stations that aren’t performing properly could spell disaster, especially if an overflow occurs. A sanitary sewer overflow (SSO) can result in unsanitary conditions, property damage, and a hefty fine. Therefore, monitoring the water level in the wastewater lift station is critical. Level sensors can be used to trip alarms or turn on/off pumps automatically if an alarm condition exists.

With many different level sensors on the market, choosing the right option can be overwhelming. At Automation Products Group, Inc. (APG), we offer several solutions for lift station management. We’ll break down the different types of levels sensors you can use for your lift stations.

What is a Lift Station?

A lift station moves wastewater from a lower elevation to a higher elevation via pumps. A lift station is important in transporting sewage from residential areas to wastewater treatment plants. Sewage flows into the station’s wet well chamber via gravity. A pump at the bottom of the chamber turns on when the sewage reaches a specified depth and pumps the sewage out of the chamber at a higher elevation. Level measurement is used for accurate pump control both to initial pump high levels and to turn them off at low levels to prevent dry-running.

How is Level Measurement Used in Lift Stations?

For accurate pump control, instrumentation is needed to initiate pumping when liquid levels are high and then turn the pumps off when liquid levels are low to prevent pumps from dry-running. Since lift stations primarily deal with wastewater and other unpleasant particles, the sensors must be durable enough to handle both the turbulence and debris.

Level Sensors in Lift Stations

There are a variety of instruments available to use for lift station monitoring. At APG, we offer several different kinds of industrial level sensors for your lift station.

Ultrasonic Level Sensors: A popular solution in a non-contact approach to level measurement, ultrasonic level sensors use sound waves to determine the liquid level inside the lift station. They avoid the turbulence and debris entirely by being mounted near the top of the lift station. APG’s LPU-2428 is a great fit for this, designed for hazardous locations and with an intrinsically safe design.

Since ultrasonic level sensors rely on sound waves echoing off of their targets, foam becomes a challenge. Foam will absorb a sound wave rather than reflect it. In foamy applications, ultrasonic level sensors have erratic readings or lose an echo completely.

Pipes in lift stations pose another challenge. The signal from the sensor will bounce off a pipe instead of the water, giving a false reading. Ultrasonic level sensors perform optimally when the sensor has a clear line of sight down to the water level in the lift station. Another solution is installing a stilling pipe to isolate the signal, or to use another technology.

Float Switches: Float switches are prized for their simplicity. The Kari multi-switch point float allows monitoring with a single float capable of multiple levels of point detection. The Kari multi-level cable float switch allows for up to four level alerts in one switch: start (to start up the pump), stop (to stop the pump), high level alarm, and low-level alarm.

The Kari float switch has multiple switches within one float housing that switch at different angles. A control weight is fixed at a point along the cable, making the float tilt as the liquid rises. The increasing tilt of the float activates the switches at different levels. For example, when the water level rises to a point where the override float changes to “on,” a pump will begin to run until the water level is pumped down to the point where the Kari float signals the “off” stage.

Submersible Pressure Transducers: Submersible pressure transducers are an excellent choice in lift stations because of their specialized design for watery environments. They’re placed at the bottom of the lift station and measure the pressure exerted by the liquid to get the level measurement. With water constantly flowing in, and pumps turning on and off, there’s almost always some wave action in a lift station.

Submersible pressure transducers are a popular choice for continuous measurement in a lift station. Their measurements aren’t affected by foam, vapor layers and physical obstructions that often cause problems for ultrasonic level sensors, and they’re easy to install. APG’s PT-500-P30 submersible pressure transducer is commonly used in lift stations and other wastewater applications, with a protective cage to keep the transducer’s face safe from scratching and damage. The PT-503 submersible pressure transducer is also an excellent choice, with its durable PDVF body for unmatched reliability and excellent chemical compatibility.

These sensors operate much like ultrasonic level sensors; except they use stronger radar waves for measurement. These stronger waves allow them to see through certain kinds of plastic, meaning that some plastic pipes inside lift stations won’t give false reading. The TRUE ECHO® CR-L radar level sensor from APG offers precision measurement. And if the water level rises too much to overtake your radar level sensor, consider a radar level sensor with a built-in submersible pressure transmitter: the TRUE ECHO Plus.

The TRUE ECHO Plus is a submersible radar level transmitter that combines accurate radar technology with the precision of a submersible pressure transducer. It’s primarily used in areas prone to flooding, and a lift station flood can turn into a serious, hazardous mess. The TRUE ECHO Plus sensor will quietly monitor like a normal radar level sensor. When the water level rises and submerges the sensor’s body, the pressure sensor takes over for sensing. This allows the radar sensor to be placed lower in the lift station without sacrificing accuracy when liquid levels rise. The PVDF housing keeps the entire sensor safe from being damaged by the nastiness lurking in a lift station.

Protect Your Lift Stations with Accurate Level Measurement

Reliable lift station performance depends on accurate level measurement. Whether you need ultrasonic, radar, float switch, or submersible pressure solutions, APG provides rugged and dependable sensors designed to handle the harsh realities of wastewater environments. Our experts are ready to help you select the right sensor for your application so your operations stay safe, efficient, and compliant.