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LT-73X Series Ultra-Low Turbidity Sensors
- Product Details
- Specifications
- Applications & Features
- Installation
- Cleaning & Calibration
- Drinking Water Solutions
LT-73X Series Ultra-Low Turbidity Sensors
Inline Turbidity Measurement Down to 0.001 NTU
The Pyxis LT-73X series measure very low turbidity continuously, with a resolution of 0.001 NTU, for drinking water, filtered water and industrial water. Three ranges are available, each with a choice of light source:
- LT-737 – 0.001 to 5 NTU
- LT-739 – 0.001 to 40 NTU
- LT-736 – 0.002 to 1,000 NTU
The standard models use a warm white LED and meet US EPA method 180.1. The “B” models (LT-737B, LT-739B, LT-736B) use an 860 nm infrared LED and meet ISO 7027.
Flat Quartz Window
The sensor reads scattered light at 90° through a flat quartz glass window at its tip. The flat face stays clean for longer, is easy to wipe, and stops air bubbles settling on the optics. Kept clean, the calibration drifts less than 0.02 NTU in a year.
The sensor gives an isolated 4–20 mA output and RS-485 Modbus, and can be checked, cleaned and calibrated over Bluetooth® from the uPyxis® app with the MA-CR adapter.
LT-73X Series Specifications
| Item | LT-737 / LT-737B | LT-739 / LT-739B | LT-736 / LT-736B |
|---|---|---|---|
| Part Number (white / infrared) | 53216 / 53224 | 53221 / 53225 | 53215 / 53223 |
| Range | 0.001 – 5.000 NTU | 0.001 – 40.00 NTU | 0.002 – 1,000 NTU |
| Light Source | Warm white LED, US EPA 180.1; or 860 nm infrared LED (B models), ISO 7027 | ||
| Accuracy with FR-100 | ±0.005 NTU or 1% | ±0.005 NTU or 2% below 10 NTU; ±0.01 NTU or 2% above | ±0.005 NTU or 2% below 40 NTU; ±0.02 NTU or 2% above |
| Accuracy with FT-100 | ±0.01 NTU or 1% | ±0.01 NTU or 2% below 10 NTU; ±0.02 NTU or 2% above | ±0.01 NTU or 2% below 40 NTU; ±0.05 NTU or 2% above |
| Repeatability with FR-100 | ±0.001 NTU or 0.5% | ±0.001 NTU or 0.5% below 10 NTU; ±0.01 NTU or 1% above | ±0.001 NTU or 0.5% below 40 NTU; ±0.02 NTU or 1% above |
| Repeatability with FT-100 | ±0.002 NTU or 1% | ±0.002 NTU or 1% below 10 NTU; ±0.02 NTU or 1% above | ±0.002 NTU or 1% below 40 NTU; ±0.05 NTU or 1% above |
| Calibration Stability (clean sensor) | Below 0.01 NTU drift a year | Below 0.02 NTU drift a year | Below 0.02 NTU drift a year |
| Power Supply | 22 – 26 V DC, 1.5 W | ||
| Outputs | Isolated 4–20 mA and isolated RS-485 Modbus | ||
| Wireless Access | Bluetooth® with the MA-CR or PowerPACK adapter | ||
| Installation | FR-100 flow reservoir, or FT-100 inline tee (1.5" NPT) | ||
| Pressure | Sensor and FT-100 up to 6.9 bar (100 psi); FR-100 at atmospheric pressure | ||
| Sample Temperature | 1 – 50 °C | ||
| Sample Flow | FR-100: 200 – 1,800 mL/min; FT-100: up to 40 L/min | ||
| Wetted Materials | 304 stainless steel, PVC, polycarbonate, quartz glass | ||
| Weight | 800 g (sensor only) | ||
| Dimensions | 189 mm long, 36 mm diameter | ||
| Cable | 1.5 m cable with 8-pin connectors, and flying-lead cable; extensions available | ||
| Protection | IP67 (sensor) | ||
| Approvals | CE, RoHS | ||
Applications
- Drinking water treatment and distribution
- Filter performance monitoring
- Reverse osmosis and desalination
- Industrial process water and boiler feedwater
- Any water where turbidity must be measured below 1 NTU
Key Features
- Resolution down to 0.001 NTU
- Three ranges: 0–5, 0–40 and 0–1,000 NTU
- White LED to US EPA 180.1, or infrared LED to ISO 7027
- Flat quartz window: stays clean, resists air bubbles
- Calibration drift below 0.02 NTU a year when clean
- Isolated 4–20 mA and RS-485 Modbus outputs
- Bluetooth® diagnostics, cleaning and calibration via the uPyxis® app
- Stainless steel body, IP67
- Fits the FR-100 flow reservoir or the FT-100 inline tee
FR-100 Flow Reservoir (Drinking Water)
For drinking water, Pyxis recommends the FR-100 flow reservoir. It runs as a bypass at 200 – 1,800 mL/min and calms the sample before it is measured: air bubbles escape, and large particles and precipitated iron and manganese settle out. It is designed to keep stray light away from the sensor.
The FR-100 mounts on a wall or panel and comes complete with an isolation valve and pressure-reducing valve on the ¼” inlet, an inline flow meter, a ⅜” sample outlet with overflow, and a ½” bottom blowdown valve for flushing solids. The sensor fits through a union on the side wall, and the empty, clean reservoir doubles as a zero-point check.
FT-100 Inline Tee
Where space is short or the line is under pressure, the FT-100 inline tee holds the sensor directly in a bypass line: up to 40 L/min and 6.9 bar. It is made of schedule 40 CPVC, angled 45° downwards so the sensor stays cleaner, and has 1.5″ FNPT and socket adapters with quick unions. It can also serve as a zero-point check when emptied and cleaned.
Both the FR-100 and FT-100 are available separately, as are replacement sensors.
Cleaning and Calibration
The LT-73X is very stable. Regular cleaning of the quartz window is usually all it needs: kept clean, Pyxis guarantees calibration drift below 0.02 NTU a year. In most waters, installed in the FR-100 or FT-100, the sensor stays accurate for about a month between cleans. Waters with more suspended solids, iron, manganese, oil or bacteria need cleaning more often.
When calibration is needed, it can be done wirelessly from the uPyxis® app, with the MA-CR or PowerPACK Bluetooth® adapter. Field calibration uses Pyxis formazin standards or the solid-state calibration kit; Pyxis also offers factory ultra-pure calibration.
