REPORT

 

 

 

 

 

 

 

Kirton Ranch Water Samplers: Ultrasonic Proximity Sensor Implementation and pump auto trigger switch

 

 

 

 

 

 

 

 

 

 

 

Ramy Atiyeh

Southern DataStream

132 North Lee St.

LaBelle

Florida 33935

 

July 19, 2002

 

 

 

 

 

 

 

 

 

 

Abstract

 

 

 

Southern DataStream specializes in hydrological monitoring equipment, BMP research, data collection and results analysis. The current project (C-11653 Biosolids project) evaluates the plant soil, and water phosphorous (P) implications of applying domestic wastewater residuals (biosolids), animal manure, and water treatment residuals to south-central Florida cattle pastures. Water samples are collected through 51 fully automated self-powered water samplers and are monitored through an extensive networks of sensors and data loggers. These instruments designed and manufactured by Southern DataStream are able to sample the water flowing through a Parshall flume without any software control. The very easy control system makes this new water sampler cheap and easy to maintain. The proportionality constant between the sample and the flow rate allows the automatic measurement of the flow rate. Recently, six new Electro Corporation PCUA Ultrasonic Proximity Sensors (Analog Output Model) have been installed on three plots in the Kirton Ranch field to measure accurately the flow rate in the flume. Efforts are currently being made to improve the automatic water sampler pump trigger by shifting from a magnetic water level detector to a mechanical trigger switch, which have numerous advantages.

 

Flow rate measurement: PCUA Ultrasonic Proximity Sensors:

 

 

The need for implementing such sensors arose with the need to remotely monitor water levels and flow rates entering the Parshall flumes of the water samplers (fig.1). The most obvious choice was to use Ultrasonic Proximity sensors, which accurately detect water levels at the entrance and the exit of the Parshall flume. Advantages of such flume are self-cleaning, low head loss and the ability to function over a wide operating range while requiring only a single head measurement. It may withstand relatively high degrees of submergence without affecting the rate of flow.

 

Figure 1 Water Sampler

 

The mounting design of the Ultrasonic sensors on the flume (fig.2) was relatively easy to handle. For each sampler two sensors were used. They were installed in two separate waterproof plastic boxes, which in turn were mounted on an aluminum frame. Aluminum was chosen for its light weight, corrosion resistance, cheap cost and hardness.

Figure 2 Parshall flume

 

However, the most challenging and time-consuming task was the sensors’ calibration. The voltage output of each sensor had to be within 0 up to a maximum of 2 volts since the CR-10 module we are using, reads only a maximum voltage of 2.5 volts. A model of a sensor holder with adjustable height (4” to 17”) was built in order to help us with the calibration procedure. To shift the characteristic curve of the sensors to desirable levels, I had to adjust the span and the zero suppression using the built-in potentiometers.

 

Once this process was achieved the sensors were mounted in the watertight plastic boxes onto the aluminum frame and the proper connection were made. The whole mountings were taken to the Kirton Ranch field where they were screwed to the wooden frame of the water samplers just above the Parshall flume. However, unfortunate technical difficulties with the CR-10s prevented us from connecting the sensors to the system. The following table summarizes the status of each one of the sensors.

 

 

 

 

Summary

Sensor

Connections

Frame mounting

Calibration

1

Not connected

Ok

Ok

2

Not connected

Ok

Ok

3

Not connected

Ok

Ok

4

Not connected

Ok

Ok

5

Not connected

Ok

Ok

6

Not connected

Not available

Not available

Table 1Sensors’  status

 

Pump auto trigger switch:

 

We are currently investigating the possibility of changing the magnetic switch that is used in initiating the pump when the water level inside the collecting cylinder reaches a certain level. The major problem encountered with this system is that the magnetic switch depends on the float that it is mounted on and if for any reason the float gets stuck the pump won’t be triggered to collect the desirable water sample.

What we are looking for is a fail free mechanical, waterproof solution that will allow us t overcome the previously stated problem.

This issue is to be pursued next week.

 

 

Field work:

 

I had the chance to interact with the actual water samplers placed in the Kirton Ranch Field. My work consisted of checking and securing all of the gator locks used on the T-splitters with the help of Brad (fig.3).

 

Figure 3 T-splitter and Gator Locks

 

In addition, I worked on collecting data relevant for the telemetry system: Benjamin and me read all of the battery and solar panel voltages in order to determine which ones are malfunctioning. This served as well to determine the probable cause of failure of some of the control units connected to the water samplers.

 

I have also learned the procedure for collecting data from the wells which allow to determine an important parameter, soil transmissibility.

The procedure is described below:

1.     Clean well from any residuals with the special brush (fig.4)

2.     Measure the water depth from ground reference

3.     Pump water out of the well using the waste pump

4.     Measure the pumping discharge rate with the help of known volume bucket and a stop watch

5.     Measure again the depth of water

6.     Record all data on spreadsheet to take to the office or lab

However, during that day we encountered a small problem, which would have prevented us from undertaking the experiments. The waste pump was not working properly. The problem was quickly identified as air leakage through the pump that was preventing the creation of vacuum in side the impellers chamber. So, Marat and me had to dismantle it and check all the joints. Finally we managed to locate the leakage. It was located at the threads of the inlet pipe. Silicon sealant was used to overcome this problem.

 

 

 

At the end of this report, you will find attached my updated daily report sheet.

 

References:

 

1.     Southern DataStream website: www.southerndatastream.com

 

 

2.     Biosolids Project website: www.residuals.ws