Room 151: ECARS Room
ECARS is an acronym for Environmentally Controlled Aquatic Recirculating System. Each system is made up of a double drain tank with an external standpipe, a pump, a bubble washed bead filter, a UV sterilizer and a temperature controller. These systems were designed in Aqualab for small system setups. Each system is computer controlled. There are twelve units in this room. Access to tanks 1-6 is through door marked 151 a, for tanks 7-12 through door marked 151 b.
Tank: The tanks used for the systems found in this room are six feet in diameter with double drains, two inches of insulation on the sides and bottom. Each tank is supplied with a photolid complete with a photoperiod controlled light and a sliding door. The tank has a reservoir in the centre below the airstone, due to the flow dynamics of the tank excess food and faeces is drawn into this reservoir and concentrated. The reservoir is part of the external standpipe/drain system for the tank. The standpipe is a loop with a valved bypass at the base. This valve needs to be opened daily to expel the waste built up in the reservoir. Opening this valve will also drain the tank. Please do not drain the tank at the end of an experiment without consulting Aqualab staff. The temperature controller and the pump must be shutoff prior to draining the tank otherwise damage to these pieces of equipment can occur.
Filter: The filter supplied with the system is a bubble washed bead filter. Due to the flow dynamics of the tank this filter acts as a biofilter. Water for the recirculation is drawn from the small peripheral drain.
UV Sterilization: The UV sterilizer located on the system is a single bulb Aqualogic sterilizer provided by Trojan Industries. It is located between the bubble bead filter and the temperature controller.
Temperature control: Temperature control is achieved in much the same way as it is accomplished in an environmental chamber. These custom made controllers (Constant Temperature Control) are composed of a refrigeration compressor, a hot gas bypass valve, a heat exchanger and a computer interface. The units run continuously and temperature control is maintained by modulation of the hot gas bypass valve and monitored by a thermistor mounted in the outflow of the heat exchanger.
Makeup water: Raw water is added to the tank’s recirculation system on a regular basis. The volume added is determined by the user, the Argus™ system opens and closes the make-up water solenoid valve (a pulse). The number of pulses per day is determined by the volume to be added per day and the volume of water that passes the paddlewheel flow sensor in 1 minute. The make-up water system is composed of a paddlewheel flow sensor and a solenoid valve on a ½" PVC supply line . Water is fed directly from Aqualab’s pre-filtration system into the tank’s recirculation return line.
Control System: Argus™ controls and monitors the pump, the make-up water supply, the water temperature, the tank’s photoperiod and two receptacles located on the walls of room 151.
Flow: The system has a paddlewheel flow sensor on the recirculation return line, that is monitored and alarmed. The pump has a temperature sensor located on the output to monitor and protect it from overheating caused be cavitation.
Make-up water: A paddlewheel flow sensor is integral to the make-up water system.
Water Temperature: The heat exchanger has a temperature sensor used to control, monitor and alarm water temperature.
Alarms: There are a number of parameters within the ECARS that can be alarmed. As previously mentioned, there are alarms for recirculation flow, photoperiod and water temperature deviation. There is also a Control Override for the system as well. If the water temperature rises above a preset point or drops below another preset point, the control system will cut all power to the controller. Immediately the system will go into the highest alarm state and activate the Control Override Alarm, an audible alarm and the auto dialer will be activated to notify personnel of the problem. Power will be restored when water temperature returns to normal or by the Facility Manager. Operating in conjunction with the control override are manual temperature controllers. These manual controllers also act to cut power to the chamber during times of temperature extreme. These manual controls need to be reset after environmental conditions are changed usually at the beginning of new experiments. There is also a Low Air Pressure Alarm on the regenerative air system.