Using a supervisory control and data acquisition system developed and sponsored by Adroit Technologies, Bayworld Aquarium in Port Elizabeth has implemented one of the most comprehensive automated aquarium management systems in the country. The project to automate the monitoring of temperature, pH, oxygen reduction potential (ORP), free chlorine, water level, filter flow rate and pressure, chlorination and pump operation within the marine systems at Bayworld has already proven its worth, saving the lives of many marine species through the Adroit advanced alarming system.
The predator tank is home to many species of sharks and other marine carnivores that are particularly sensitive to even the slightest change in temperature. The tank must be kept below 25°C to accommodate the most thin-skinned of these species, the spotted gully sharks. With a temperature increase as little as 2°, Bayworld had already lost two of these animals to abnormally high temperatures in the past. A heatwave that Port Elizabeth experienced at the beginning of this year lasted over two months, the result of which were consistently high life-threatening temperatures that were experienced in the predator tank.
Repeated alarms by the Adroit scada system alerted the aquarists of potentially dangerous temperatures within the tank. After querying the temperature trends for the month, it was decided that action needed to be taken to prevent any further loss of life. Volunteers and staff rallied to form a human conveyor belt depositing 10 tons of ice, donated by a local fishery, into the tank in an attempted to lower the tank temperature. Efforts were successful, and the tank temperature decreased by a degree, a small change that was enough to ensure a temperature buffer for the next two days until a predicted and long awaited cold front moved in, saving the lives of many marine creatures.
In the early 1990s, chlorine gas from a nearby pump station found its way into the aquarium killing all the marine life in the main tank. This disaster alerted the staff at Bayworld of the advantages of a warning system with remote alarming.
Volunteer Dylan Bailey, technical aquarist: Aquarium Research at Bayworld, wanted to implement a system of remote alarming and improved monitoring using a scada system but discovered that South African aquariums were not generally using scadas to monitor their facilities. Thus Bailey set about designing and implementing a monitoring system for the aquarium that is one of the most effective water management systems in South Africa, so effective that Reef HQ, a Great Barrier Reef aquarium on the east coast of Australia, is using it as an international benchmark.
The aquarium's previous scada system supported only one make of modem, but Adroit enabled much more flexibility in how Bayworld chose to set up this critical part of the system. The facility chose to use an e-mail and SMS service in Johannesburg because of the remote nature of SMS alarming, its global application, ease of use and cost effective nature.
Bailey is currently using technology provided by Adroit to enable the alarming to work with Outlook Express. Initially, the Adroit scada sets off an audible alarm in the passage, which, if unattended, escalates to deploying an SMS to the relevant staff member. If the problems relate to the dolphin lake or the water intake and treatment plant, for example, the SMS is sent to the technical manager of the aquarium. If no one responds to the SMS alarm, the system will escalate the warning and send SMS notices to other aquarium staff and will eventually trigger an alarm to Bayworld's security company. The security company then has a list of telephone numbers that it will use to contact aquarium staff.
Bailey used scripting to integrate the scada system with Bayworld's intranet thereby providing a web page that is visible to staff and is updated every five seconds. The aquarium plans to load this onto its Internet site with two-hourly updates and remote access.
Bayworld use a simple system architecture set-up with a purchased Alan Bradley 5/03 PLC. The PLC has a 16 channel analog input card for analog instruments, a 16 channel digital input card for pump and plant operation monitoring, and an eight-channel digital output card to enable a visual alert of alarm conditions. The PLC is connected to the PC running the Adroit scada via an RS232 link. Bailey is currently implementing a system whereby an e-mail message is sent concurrently with the SMS alarm that provides a more detailed summary and overview of the problem that the facility is being alerted to.
Bayworld had been running on an antiquated system that had been hardwired to an analog board. Information about pumps and water flow was so technically complicated on this system, that non-technical staff would not use the system, leaving it vulnerable over the weekends and other periods of time when technical staff where not on duty to monitor the system. The higher level of automation that the Adroit scada provided and the flexible graphical interface, logging and alarming made it accessible to all.
Following a feasibility study and a search for project sponsorship, Bailey implemented the Adroit system in approximately six months. He comments, "We have had better results from the Adroit scada: its object orientation makes it more flexible and its modular design makes upgrades easy. The start-up is quick which is significant after power failures where critical systems may have shut down and altered chlorine and water levels as well as temperature which are very important variables in the health of the aquariums different marine life. The scada is also very resource efficient (it is currently running effectively on 196 Megs of RAM) and changes to various aspects of the system can be implemented without interrupting the running of the system as a whole. Lastly, the Adroit Access Agent allows the user to log files to an Access database which has the advantage of the user being able to set it up as they want, and data can also be imported without it having to be modified."
The scada is running on a Pentium III 700MHz PC on a Windows NT Workstation Version 4 platform. Bayworld's 16 instruments required architecture with low complexity. Using existing cabling, Bailey connected each instrument to the PLC via 4-20 mA current loops. The aquarium opted for a distributed online sampling scheme for the water management system, primarily because of the simplicity of the system and long distances to the monitoring system. Endress + Hauser sponsored more than half of the instruments, which have proven to be very reliable, Bailey comments, "The pH probes can be left uncalibrated for up to four months and still remain remarkably accurate."
Bayworld began the project by identifying their most critical systems and how to set up the structure they would monitor. They identified the water intake and chlorination plant, the dechlorination plant feeding the aquariums, the PH of incoming water and the predator tank, dolphin lake and tropical tanks. These three main tanks are particularly important as all the smaller displays are fed water from these principal ones.
In aquarium situations, effective water management must ensure that all ecosystem functions are operating satisfactorily. This involves maintaining a balance within all ecological processes within the system by monitoring and altering certain variables accordingly.
The dolphin lake and seal pools are constantly chlorinated and filtered via six large sand filters. The predator tank is filtered by eleven sand filters and has two airlifts within the tank to facilitate water movement and aeration. While the tropical tank is filtered through an under-gravel filter and then through six algal scrubbers and heated by six, three-kilowatt hotrods.
The new Adroit system monitors all main pumps and blowers on the tropical and predator tanks, filter flow rate on the predator tank to ensure adequate backwashing, flow and filtration operation, the dolphin lake chlorinator operation, chlorine feeds to sea intake and the aquarium dechlorinator chlorine leakage alarm. In terms of water chemistry, the scada monitors upgraded free chlorine and pH measurement on the dolphin lake, ORP and pH on the tropical and predator tanks, temperature on the dolphin lake, predator and tropical tanks and the pH of the incoming seawater.
Traditionally, portable pH, salinity and temperature instruments were used to carry out water tests. Additional tests such as nitrate, phosphate, free chlorine and total chlorine (for the dolphin pools) were carried out using a HACH DR890 colorimeter. Volunteers performed most of the tests manually, and there were frequently times where tests were not performed, sometimes for up to weeks on end.
Bayworld uses Adroit's realtime trending facility to monitor temperature and other variables over a fixed time period. Using historical data, the aquarium developed an average in Excel, which they use as a model against which to base current conditions and information. Information is assimilated from a variety of sources and across various time spans to generate reports and trends on such variables as manual daily/weekly pH, temperature, salinity tests of smaller exhibits and holding/quarantine pools, manual weekly tests of ammonia, reactive phosphorus and nitrates from all tanks, continuous hourly recorded data from the water management system and observations from tanks, animal day sheets, feeding and maintenance schedules, and so forth.
Bailey concludes, "Many of the new emerging concepts in managing large captive marine ecosystems require the availability of continuous, reliable data to be implemented effectively. Bayworld has implemented the latest concepts in aquarium management, that of system modelling. Using techniques such as this, we can determine the ideal conditions for a given marine ecosystem and use them as an idealised model in the management of the system."
For more information contact Adroit Technologies, 011 781 3513, [email protected], www.adroit.co.za
| Tel: | +27 11 658 8100 |
| Email: | [email protected] |
| www: | www.adroit.co.za |
| Articles: | More information and articles about Adroit Technologies |
© Technews Publishing (Pty) Ltd | All Rights Reserved
printer friendly version