The principle of operation is based on maintaining the water level in a Class 1 pan to a nominal 190mm by charging or discharging the pan periodically. The water level is measured in a still-well mounted in the transducer enclosure that is hydraulically connected to the pan. The principle of water level measurement is temperature compensated high frequency ultrasonic reflectometry that has a resolution of better than 0.2mm required for Class 1 transducers. An accurate load cell is also used as a backup to ensure complete control from near empty to near overflow. Valves and pumps under microprocessor control implement the charging and discharging of water. Periodically (user controlled) the controller initiates a self-test procedure that involves the discharging and recharging of a small quantity of water to ensure proper operation and calibration. Surface temperature is measured by a sensor just below the surface of the water in the pan. The RIM9200 incorporates a multi-line LCD display that continually indicates water level, temperature and operational status. Outputs are via the inbuilt RS232/RS422 port and isolated contact closures. The output allows both real time and accumulated data to be collected. The RIMCO 9200 requires a clean water supply with a pressure of at least 0.2 bar and a capacity determined by the estimated maximum evaporation rate over the unattended period plus provision for the periodic self tests.
Automatic periodic charge and discharge to test for proper operation. Alarm output is set if test fails but transducer continues to operate (where possible). Alarm must be manually reset. Test period is user selectable at intervals of 24 hours, 7 days or not at all.
Commands via RS422 or RS232 port (switch selectable).
The transducer enclosure is mounted immediately adjacent to the pan (380 x 380 x 250mm) with its top just below the height of a Class A pan. The enclosure is a weatherproof, high impact, UV resistant painted steel enclosure with a hinged access door.
Hydraulic connection between the pan and the enclosure is by ½” ID diameter tubing. Charge and discharge plumbing fixtures from the control box are by standard brass low-pressure male ½” barbed fittings.
Electrical cable entry is by standard industrial glanded fitting and terminated within the control box by industrial grade screw terminations.
|Technologies||Ultrasonics and Mass measurements.|
|Water Level||190mm nominal|
|Water Charge||By solenoid valve|
|Water Discharge||By solenoid valve or pump|
|Charge Pressure||0.2 bar (3psi) minimum
6.0 bar (87psi) maximum
|Hydraulic Fittings||½” Male barbed fitting - Brass|
|Better than 0.2mm.
Evaporation - Temperature
|±3% averaged 24 hours or
±0.2mm whichever is greater.
±3% or ±0.5°C whichever is greater.
|Operating Temperature||0°C to +60°C evaporation.
-10°C to +60°C ambient.
|Power Supply : 12 to 24V dc, 500mA nominal, 3A max.|
|Evaporation : Isolated contact closure pulse of 50-100mSec for every 0.2mm discharge and recharge (separate and isolated).|
|Surface Temperature : 0 to 1V, -10°C to 60°.|
|Alarm : Normally open isolated contact. Closed on alarm until cleared.|
|RS422 : Automatic transmission every 1 minute stating separate accumulated charge and discharge increments, water temperature and status over that period. Fixed length ASCII string including check sum. Half duplex 9600 baud, 8 data bits, no parity and 1 stop bit.|
|LCD Display : Multiline alphanumeric Indicated water level, temperature and status.|