There shall be furnished an open channel flow system suitable for Class I Division 1 Group C, D hazardous locations and used for multi-site monitoring. The flow system shall be a compact integrated measurement and data storage system consisting of a flow module operating in the hazardous area while powered from the safe area. An area velocity sensor shall be used to measure flow rate.
2)AREA VELOCITY SENSOR
A)The sensor shall directly measure average liquid velocity using the ultrasonic Doppler technique. The sensor shall not require a multiplying factor based on flow depth to convert a point velocity to the average liquid velocity. The sensor shall not require velocity profiling and calibration at the measurement site. The sensor shall not contain electrical contacts exposed to the liquid to measure velocity. The sensor shall contain an automatic gain control amplifier that shall automatically adjust its gain based on the strength of the received Doppler signal.
i)The Doppler velocity measurement frequency shall be 500 kHz with a transmission angle of 20 degrees. The velocity measurement range of the sensor shall be from -5 to +20 feet per second (-1.5 to +6.1 meters per second). The velocity in water with a uniform velocity profile and a speed of sound of 4850 feet per second (1480 meters per second) shall be measured with a maximum error of +/-0.1 feet per second (±0.03 meters per second) over a range of -5 to +5 feet per second (-1.5 to +1.5 meters per second), and ±2% of reading over a range of 5 to 20 feet per second (1.5 to 6.1 meters per second). The typical minimum depth for velocity measurement shall be 0.08 feet (0.025 m).
B)The sensor shall also contain a differential integrated circuit pressure transducer to measure the hydrostatic pressure of the liquid to determine the liquid depth.
i)The level measurement range of the sensor shall be from 0.033 to 10.0 feet (0.010 to 3.05 m). The level shall be measured with a maximum error of ± 0.008 feet per foot (± 0.008 m per m) over a range of 0.033 to 5.0 feet (0.010 to 1.52 m), and ± 0.012 feet per foot (± 0.0012 m per m) for levels greater than 5.0 feet (1.52 m). The temperature coefficient shall be ± 0.0035 feet per degree F (± 0.0019 m per degree C) over the compensated temperature range of 32° to 122° F (0° to 50° C).
ii)The pressure transducer in the sensor shall be factory calibrated, with the calibration data stored as digital values in a microcontroller in the sensor. The sensor shall not contain potentiometers to calibrate the pressure transducer. It shall not be necessary to recalibrate the flow module, other than programming the current flow stream level, if the sensor is interchanged with another sensor. The analog output of the pressure transducer shall be converted to a digital value in the sensor, and the sensor shall transmit to the flow system a digital signal corresponding to the current level measurement. The sensor shall not transmit to the flow module an analog signal corresponding to the current level measurement. The flow module shall store the date and time that the level measurement was last adjusted.
C)The sensor shall be 0.75 inches (1.9 cm) in height and 1.31 inches (3.3 cm) in width. The sensor cable shall be 25 feet (7.62 m) long. The cable shall terminate in a push-on, quick-connect connector so that the sensor can be easily removed and replaced in the field. The connect cable for the sensor shall include a vent tube that shall reference one side of the pressure transducer to atmospheric pressure. The flow system shall include an internal desiccant cartridge with a replaceable hydrophobic filter to protect the atmospheric reference from moisture. Sensor materials exposed to the flow stream shall be epoxy, stainless steel, polyvinyl chloride (PVC), and chlorinated polyvinyl chloride (CPVC).
A)The flow module shall be capable of accepting up to 2 flow rate conversions, each of which can be either a level-to-area conversion or a level-to-flow rate conversion, allowing comparison of flow rates calculated using, for example, the continuity equation and the Manning formula. The flow module shall be capable of calculating 2 total flows, each of which shall be capable of being based on either flow rate conversion. Each total flow calculation shall accumulate either net, positive, or negative total flow with user-selectable resolution.
i)For level-to-area conversions, the flow module shall convert measured liquid level readings into the area of the flow using internal conversion algorithms. The flow module shall contain conversion information for round, U-shaped, rectangular, trapezoidal, and elliptical channels. The flow module shall accept a silt level measurement and adjust the area of the flow appropriately. The flow module shall also accept up to 50 level-area points.
ii)For level-to-flow rate conversions, measured liquid level readings shall be converted into corresponding flow rate readings using internal conversion algorithms. The flow module shall accept conversion information for V-notch weirs, rectangular weirs with and without end contractions, Cipolletti weirs, Isco Flow Metering Inserts, and Thel-Mar Weirs, and Parshall, Palmer-Bowlus, Leopold-Lagco, trapezoidal, H, HS, and HL flumes. For monitoring in applications using the Manning formula in round, U-shaped, rectangular, and trapezoidal channels, the flow module shall accept information for channel configuration and size, and slope and roughness coefficient. The flow module shall accept up to 50 level-flow rate data points. The flow module shall accept a two-term, level-flow rate polynomial equation.
B)The internal data storage memory in the flow module shall be stored in Flash memory for definite non-volatility. It shall have a capacity of 395,000 bytes, equal to up to 79,000 readings, equal to over 270 days of level and velocity readings at 15 minute intervals plus total flow and input voltage readings at 24 hour intervals. The flow module shall store data in rollover mode. The flow module shall be capable of storing level, velocity, flow rate, flow rate 2, total flow, total flow 2, and input voltage data. The data storage interval for each type of data shall be individually selectable from off, 15 or 30 seconds, 1, 5, 15, or 30 minutes, or 1, 2, 4, 12, or 24 hours. The flow module shall be capable of variable rate data storage, with the data storage interval changing based on level, velocity, flow rate, flow rate 2, total flow, total flow 2, or input voltage. It shall be possible to change the data storage setup for any data type at any time without disrupting the data storage of any other data types. It shall be possible to delete all data stored in the data storage memory. When reset, the flow module shall automatically set up default data storage, with level, velocity, and flow rate stored at 15 minute intervals, and total flow and input voltage stored at 24 hour intervals. The flow module shall store signal strength and spectrum strength diagnostics from the last 10 valid and the last 10 invalid velocity measurements.
C)The flow module shall be programmed using a software program that shall operate on a PC using Windows version 95 or later. The software shall also retrieve stored data from the flow system, and generate graphs and reports from stored data. The computer shall communicate with the flow system using an intrinsically safe RS-232 barrier cable at 38,400 baud. Connection to the flow system shall be made with a cable with a push-on, quick-connect connector that can be easily connected and removed in the field.
D)The flow module shall contain two non-volatile, programmable Flash memories, one for the program memory and one for the user program and the stored data. The program memory shall be capable of being updated via the serial port on the flow module without opening the enclosure. The flow module shall retain the user program and all stored data during program memory updates.
E)The flow module shall be equipped with modbus communications capabilities, independent of Flowlink, enabling the data to be linked to monitoring and/or process control systems and software.
F)The flow system shall be powered using an intrinsically safe power supply. The intrinsically safe power supply shall be CSA certified and provide 12 VDC from 100-240 VAC. The flow module shall have the capability of measuring and storing the input voltage.
G)The flow module shall be housed in a rugged, permanently sealed, submersible, watertight, dust-tight, corrosion resistant (self-certified NEMA 4X, 6P, and IP68) enclosure. All electrical connections within the flow module shall be soldered, or shall be pin-and-socket connections that are held in place by the flow module enclosure itself. The flow module shall not contain wiring harnesses that can be removed without a soldering iron. The flow system shall include a permanently attached back plate with integral handle and mounting holes. The flow module shall include an LED that is visible from outside the flow module. The LED shall also flash every 15 seconds for 5 minutes after a computer is disconnected from the flow module.
Isco 2151 Area Velocity Flow Module
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Teledyne Isco 2151P Area Velocity Flow System / Engineering Specifications