1720E
GENERAL
The turbidity monitoring system shall include at least one Turbidimeter and one interface unit. The system shall be capable of functioning as a single sensor system and also be easily expanded up to two turbidimeters per interface unit. The connections between the turbidimeter and interface unit will include plug & play connections.
TURBIDIMETER
The turbidimeter shall measure turbidity in the range of 0.001-100 NTU and be a
microprocessor-based, continuous-reading, on-line nephelometric instrument
meeting all design and performance criteria specified by USEPA method 180.1.
Light shall be directed through the surface of the sample and the detector shall be immersed in the sample, eliminating glass windows and flow cells. Optical components shall be mounted in a sealed head assembly that can be removed easily for calibration/service, without disturbing sample flow. The turbidimeter body shall be constructed of corrosion-resistant polystyrene, and shall include an internal bubble removal system to vent entrained air from the sample stream.
The turbidimeter shall offer the choice of formazin-based (20 or 1 NTU) or instrument comparison-based calibration methods. Accuracy shall be ±2% of reading or ±0.015 NTU (whichever is greater) from 0 to 40 NTU; ±5% of reading from 40 to 100 NTU. Displayed resolution shall be 0.0001 NTU from 0 to 9.9999 NTU; 0.001 NTU from 10.000 to 99.999 NTU and repeatability shall be better than ±1.0% of reading or 0.002 NTU (whichever is greater). User selectable signal averaging, bubble removal, alarm and recorder output hold, and self-test diagnostics shall be provided. All turbidimeters on the network shall have the option for MODBUS/RS232, MODBUS/RS485, LonWorks serial input/output capability for two-way communication to a computer or have wireless downloading capability through the IR Port located on the interface unit to download and print real-time turbidity data, calibration history, and current set points in a CSV format.
INTERFACE MODULE
The Interface unit shall allow operators to control sensor and interface functions
with user-friendly, menu-driven software, and shall provide data logging of
measurement data from up to two turbidimeters for 15 minutes, 1 hour, 24 hours, 30 days, or 180 days and the capability to transfer data to a computer or printer via direct MODBUS communications or directly into a Personal Digital Assistant (PDA) via a wireless IR Port. The interface unit will also have a built-in data logger with the storage capacity to store data on 15-minute intervals for up to 6 months with two sensors per controller. Each interface will also include two analog outputs and 3 un-powered SPDT alarm contacts. The interface unit and the DC power supply shall be housed in a NEMA-4X (indoor) industrial metal/plastic enclosure, and the power supply shall automatically accept input in the range of 100 to 230 Vac, 50/60 Hz.
SAFETY AND ELECTRICAL DESIGN STANDARDS
All system components are ETL listed to UL 61010A-1, certified by ETL to CSA C22.2 No. 1010.1, and CE certified by manufacturer for safety to EN 61010-1. For EMC immunity and emissions, system components are CE certified by manufacturer to EN 61326 (industrial levels), for North America to FCC Part 15, and Canadian Interference-Causing Equipment Regulation ICES-003, and for rest of world to CISPR 11 Class A levels.