Archive for July 2012

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.

 

 

 

 

Wireless Control of Life Support System in an Exotic Aquarium for Show Animals

Wireless Control of Life Support System in an Exotic Aquarium for Show Animals

APPLICATION

Park engineers have an application sending a 4/20mA signal from an ORP (Oxidation Reduction Potential) sensor to a Control Room approximately 500 feet away.

The ORP sensor is used to electronically monitor the amounts of sanitizer and other chemicals in the water, before it enters the large holding tank.

Rain or shine, a ladder is climbed to the top of a pump house building several times everyday to take readings. This posed a safety and health risk to the operator as well as only provided sporadic measurement cycles.

The EPA requires monitoring of this chemical system for both human and animal safety.

More Info: Frequency Hopping Spread Spectrum Technology

More Info: Value of Isolated Signal Conditioners

USER REQUIREMENTS

The ORP monitor where the reading was taken is in a hard to reach location at the top of a pump house on the side of the tank.

Due to a large amount of sidewalks and other obstacles, it was not cost effective to run wires from the sensors to the Control Room.

WIRELESS POSSIBILITY

Checking the 500 foot line of sight between the Transmitter and Receiver locations indicated there was a 50 foot elevation difference. The check of the antenna path also indicated there was a large building near the Receiver. There are also several trees in the antenna path.

More Info: How to calculate your antenna needs

WILKERSON INSTRUMENT’ SOLUTION

DR9011 With 3 Element Yagi Antenna

DR9011 With 3 Element Yagi Antenna

Use a 900 MHz Band Transmitter (DR9011, 2 analog and 4 switch inputs) at the top of the building to monitor the 4/20mA signal from the ORP sensor.

The DR9011 was installed inside a NEMA 4X housing. A small 3” high 2.1dBi gain vertical antenna was mounted on the top of the NEMA 4X housing.

Use a 900 MHz Band Receiver (DR9021, 2 analog and 4 switch outputs) at the LSS Control to receive the data coming from the DR9011 Transmitter.

This unit was installed inside a pre-existing control panel. Along with a wall mount 3 element directional Yagi antenna (8dBi gain) to the top of the LSS (Life Support System) Control building.

The use of the Omni directional antenna at the sensor end allowed the signal to be transmitted across a wider path. In using the Yagi antenna at the receiver side, the install crew was able to choose the best location and path for pointing the Yagi antenna.

The trees and building posed difficulty by either blocking part of or potentially causing a reflected signal in the Fersnel Zone. The Yagi helped eliminate this due to its narrow beam width.

This system has been reliably sending data since June 2007.

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