A06 Specifications.doc

Salient Characteristics

Turbidity Sensor The USGS Hydrologic Instrumentation Facility needs to purchase turbidity sensors. This equipment will be used for measuring turbidity at various water quality monitoring stations all over the country.

Shall include the following:

Turbidity sensor

· Shall be a ISO 7027 compliant sensor

· Shall have a nephelometric (90˚) modulated infra-red configuration

· Shall have an SDI-12 interface output

· Shall have a measurement range of at least 0-5000 NTU

· Shall have automatic range detection for proper range hopping

· Shall be factory calibrated with formazin and/or StablCal turbidity standards

· Shall be user calibratable with formazin or stabilized formazin turbidity standards

· Shall have an accuracy of no less than ±1% at 25˚ C up to 5000 NTU

· Shall have resolution ranges: up to 100 NTU ±0.01 NTU; 1000 NTU ±1.0 NTU; 5000 NTU ±2.0 NTU

· Shall have a linearity better than 2% for 0 to 5000 NTU

· Shall have temperature coefficient better than ±0.05%/˚ C

· Shall have zero drift of less than ±0.2 NTU

· Shall include a self-cleaning wiper; during wiping cycle output to remain within ±2% full scale of value prior to wipe

· Shall have a nominal wipe time of no more than 8 seconds

· Shall have wiper options including optional “scrub”

· Shall operate from external 12 VDC power supply

· Shall have a stainless-steel cover

· Shall have a depth rating of a minimum of 100 meters (328 ft.)

· Shall have a minimum operating temperature range of -10˚C to 40˚ C

· Shall include configuration tool, hardware, software, USB cable, and screw type terminal block

· Shall have a stainless-steel probe shroud

Cable

· Shall be a minimum of 25 meters in length

· Shall be compatible with turbidity sensor

· Shall include bare wires on one end

· Shall be 6 conductor and shield, grey polyurethane, glanded cable