Tag Archive for 4/20mA

Monitor Flow and Level Wirelessly at Remote Sewage Lift Stations

Monitor Flow and Level Wirelessly at Remote Sewage Lift Stations

Back in the late 1980’s a local city municipality had six lift-stations wired underground directly to their Wastewater Plant located a few miles north of Daytona International Speedway. However, in 1995 a forest fire burned the entire surrounding fields which destroyed the Level and Flow sensors and the underground wires going to the wastewater plant were melted and rendered useless.

Cost issues have been a concern for this more rural municipality. They were searching for a more economical and cost effective way to retrofit the three lift stations than reinstalling all the old hardwired systems.

Over the years, all six of the lift-stations have been repaired and upgraded. However, they have only hardwired three of the main lift-stations back to the Wastewater Plant using a data acquisition system.

The city would like to tie the remaining three lift-stations into their data acquisition system by using Wireless Telemetry. By doing this they will be able to monitor two 4/20 mADC signals coming from a Flow and Level sensor at each of the three remaining lift-stations.

The decision to use Wireless was made to help alleviate the destructive issues from the aforementioned forest fire as well as help maintain the integrity of the system given Florida’s high winds (upturned tree roots), excessive high level ground water, and encroaching metropolitan development.

All three lift stations are located about 1,000 feet apart from each other deep into the forest. However, there is a 40 foot wide clearing next to the lift-stations which the city keeps mowed as an access road to each lift-station.

DR9011 With 3 Element Yagi Antenna

DR9011 With 3 Element Yagi Antenna

In order to test the effectiveness and durability for the new proposed wireless system one of the remote non-wired stations was configured in the following manner:

·        3-Element, 8 dBi Gain Yagi Antenna was installed on a small 10 foot tower at one lift-station

·        A DR9011 wireless transmitter was installed in the existing enclosure along with the Flow and Level sensors producing the 4/20 mADC signals.

·       A DR9021 Wireless Receiver was mounted approximately 3000 ft away at one of the main lift-stations.

DR9021 Wireless Receiver

DR9021 Wireless Receiver

·        The 4/20 mA signals out of the DR9021 Receiver were wired directly into the existing data acquisition system to be sent back to the Wastewater Plant for monitoring.

The system has been running trouble free for over two years (2012) and the two other wireless systems are due for installation when time and funds are available.

Note: The lift station supervisor said that by using the Wilkerson Instrument Company wireless system they will be saving the City over $25,000 for the 3 installations.

Replacing Bubbler Pump Controllers With Up to Date Level Monitors

Replacing Bubbler Pump Controllers With Up-to-Date Level Monitors

A local City wastewater treatment plant monitors their sewage levels at over 200 lift stations using Duplex and Triplex Bubbler Pump Controllers.

The city lift station supervisors said they were spending extremely too much of their labor time replacing broken parts and retrofitting components on the Bubbler Systems.

Common complaints in using a Bubbler System include failures with the pressure transducers, clogged flow pipes and hoses clogged with materials found in the liquid.

Sensor response time can also lag behind when fluid level changes in the tank. Cold weather and freezing compressed air can also cause the regulator to fail. 

Accuracy is dependent on a constant supply of air and may vary by as much as 10% of the full scale due to temperature. Air compressors are the typical source of compressed air.  They have to be replaced after a few years. The compressors also use costly electricity.

Our solution was to install a level monitor in conjunction with a submersible pressure transducer.

LS1000 Level Sensor

LS1000 Level Sensor

The LS1000 transducer is a large diaphragm pressure sensor.  It has a heavy Stainless Steel structure and sits on the bottom of the lift station tank.  The transducer has a built in 2 wire transmitter and has an output of 4mA to 20mA proportional to the fluid pressure at the bottom of the tank.

The LM1000 level monitor can be directly installed into the same housing of most of the pre-existing bubbler systems being replaced. This makes the installation process much easier and faster.

 

LM1000 Level Monitor

LM1000 Level Monitor

The level monitor comes with a built in level sensor calibrator, bright 4 digit LED display in feet to two decimal places, relay alarm with adjustable set points, built in 24 VDC power supply for the sensor transducer power supply and a 4mA to 20mA  output.

After installing the Level Monitor, you can just drop the LS1000-10-40 level transducer into your tank and wire directly to the Level Monitor power supply.

The advantages of using a Submersible Level Sensor are lowering product cost to a third of that of a bubbler system and a faster and easier installation.

All electronics are encapsulated inside the rugged 316 stainless-steel housing.

The transducer is not affected by changes in air temperature or by foam, soap, and other materials in the tank.

It has a constant, fast response time for updating sensor level changes, a 0.5% Span accuracy, and is rugged with a high reliability.  

DR9011 With 3 Element Yagi Antenna

DR9011 With 3 Element Yagi Antenna

 

Each Bubbler System can cost in excess of $4,000.00. The city can purchase both a LM1000 Level Monitor and an LS1000 Level Sensor for $1,350.00 (about a third of the cost of (1) Bubbler System).

 

An upgrade option to the system is remote level monitoring via wireless data transmission. By utilizing a wireless Transmitter and Receiver package, monitoring of the system can be accomplished many miles away, real time.

 

 

 

 

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