Nephelometric or transmittance measuring – The nephelometric measurement at 90° scattered light is advantageous for lower turbidity, whereas the transmission measurement at 180° is beneficial for medium to high turbidity values: With increasing turbidity, restray and scattering effects between particles are growing bigger. The reduction of light intensity in this case leads to a more accurate result than a 90° nephelometric measurement. Therefore, lab meters for high values are equipped with several measuring options: Ratio modes calculate the final result from different measured angles. For ratiometric measurements, there is no specific standard method to be followed; rather, procedures are established by the application or industry.
White light has a higher sensitivity for small particles, however, the inherent coloration of the solution has a stronger disturbing effect in this case. The IR measurement is required by DIN ISO, the white light measuring by US EPA.
Application areas for turbidity measuring
| Turb® 355 T/IR | Turb® 430 T/IR | Turb® 550/Turb® 550 IR | Turb® 555/Turb® 555 | |
| Applications | Portable use for waste-water, surface water and ground water applications | Portable use for all water testing applications incl. drinking water, wine industry, process control Laboratory use: optional for all applica-tions up to 1100 NTU/ FNU with LabStation | Meter for routine and precise measurements | Meter for routine and precise measurements including QC of com-plex samples and high turbidity values. |
| Light source | Tungsten lamp/IR LED | Tungsten lamp/IR LED | Tungsten lamp/IR LED | Tungsten lamp/IR LED |
| Measuring range | 0-1100 NTU/FNU | 0-1100 NTU/FNU | 0-1000 NTU/FNU | 0-10000 NTU/FNU/FAU |
| Calibration | Automatic 1-3 point | Automatic 3 point | Automatic 1-3 point | Automatic 1-5 point |
| Special features | Portable field meter | Portable field meter Calibration interval Calibration documentation Storage for measure values Optional: LabStation, LSdata | AQA Flow-through measurement (unpressurized) | AQA complete with password protection, ratio method for the reduction of interferences; transmission, flow-through measurement (unpressurized/ up to 4 bar) |
Benchtop Turbidimeters
| Turb® 550 | Turb® 550 IR | Turb® 555 | Turb® 555 IR | |
| Measuring principles | Nephelometric | Nephelometric | ||
| Light source | Tungsten lamp | IR-LED | Tungsten lamp | IR-LED |
| Measuring range NTU FNU EBC Nephelos FAU |
0 … 1000 – – – – |
0 … 1000 0 … 1000 – – – |
0 … 10000 – 0 … 2450 0 … 67000 – |
0 … 10000 0 … 10000 0 … 2450 – 0 … 10000 |
| Resolution | 0.01 NTU from 0.00 … 9.99 0.1 NTU from 10.0 … 99.9 1 NTU from 100 … 1000 |
0.0001 NTU from 0.0001 … 9.9999 NTU 0.001 NTU from 10.000 … 99.999 NTU 0.01 NTU from 100.00 … 999.99 NTU 0.1 NTU from 1000.0 … 9999.9 NTU |
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| Accuracy | ±2% of value or ±0.01 NTU | 0 … 1000 NTU: ±2% of value or ±0.01 NTU 1000 … 4000 NTU: ±5% of value 4000 … 10000 NTU: ±10% of value |
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| Reproducibility | ±1% of value or ±0.01 NTU | |||
| Calibration | Automatic 1…3 point calibration | Automatic 1…5 point calibration | ||
| Response time | < 3 seconds | < 6 seconds | ||
| Cuvettes | 28 x 70 mm (1.1 x 2.76 in) round cuvette, 25 ml sample volume | |||
| AQA functions | Calibration interval monitoring Calibration protocol |
Calbration interval monitoring Calibration protocol Password-protected access to calibration and configuration Time-controlled data transmission |
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| Operating temperature | +10 … +40 °C (50 … 104 °F) | 0 … +50 °C (32 … 122 °F) | ||
| Power supply | Plug-in power supply 100 – 240 VAC ±10% / 47 – 63 Hz | |||
Portable Turbidimeters
| Turb® 430 IR / Turb® 430 T | Turb® 355 T / 355 IR | |
| Measuring principles | Nephelometric (90° scatter) | Nephelometric (90° scatter) |
| Light source | IR-LED/Tungsten lamp | Tungsten lamp/IR-LED |
| Measuring range NTU FNU |
0 … 1100 / 0-1100 0 … 1100 |
0 … 1100 0 … 1100 |
| Resolution | 0.01 from 0.00 … 9.99 0.1 from 10 … 99.90 1 from 100 … 1100 |
0.01NTU from 1 … 9.99 0.1 NTU from 10.0 … 99.9 1 NTU from 100 … 1000 |
| Accuracy | 0.01 NTU or ±2 % of the measured value | ±2 % of the measured value or ±0.1 NTU last decimal place in range 1 … 500 NTU ±3% of the measured value in range 500 … 1100 NTU |
| Reproducibility | <0.5% of the measured value or 0.01 NTU/FNU | ±1% of the measured value or ±0.05 NTU/FNU |
| Calibration | Automatic 3 point calibration | Automatic 1…3 point calibration |
| Response time | Approx. 3 seconds (IR) / approx. 7 seconds (T) | 14 seconds |
| Cuvettes | 28×60 mm (1.10×2.36 in.), 20 ml sample vol | 25×45 mm (0.98×1.77 in), 15 ml sample vol |
| Interface | RS 232, USB via adapter | |
| Special Functions Calibration Protocol Storage; measured value RS 232 Date/Time Data evaluation Rechargeable battery |
Yes 1000 Yes Yes Yes Optional |
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| Operating temp. | 0.. +50 °C (32..122 °F) | 0..+50 °C (3..122 °F) |
| Thomas No | Mfr No | Description |
|---|---|---|
| 1218P20 | 600311 | WTW Turb 355 IR-Portable; Nephelometric measurements acc. ISO 7027 / DIN EN 27027 with automatic 1-4 point calibration and instruction manual. |
| 1218P21 | 600312 | WTW Turb 355 T-Portable; Tungsten lamp according to US EPA battery operation. Single instrument in case with 4 AAA alkaline batteries. Calibration set (0.02 – 10.0 – 1000 NTU), 2 empty cuvettes and cleaning tissues. |
| 1218P22 | 600320 | WTW Turb 430 IR-Portable; Nephelometric measurement (90°) acc. DIN EN 27027, incl. cal std kit, 2 empty cuvettes, tissues, batt. (4 AA), suitable for drinking water. Optional LabStation LS Flex/430 w/ software for GLP compliant data export or rech. batt. Flex/430. |
| 1218P23 | 600321 | WTW Turb 430 IR/SET-Portable; Incl. cal. std kit (0.02-10-1000 NTU/FNU) in field case with insert and accessories |
| 1218P24 | 600325 | WTW Turb 430 T-Portable; (90° tungsten) acc. US EPA 180.1 incl. cal. std kit (0.02-10-1000 NTU) and accessories 2 empty cuvette (28m), cleaning tissues, batt.; suitable for drinking water. Optional LabStation LS Flex /430 with software package for GLP compliant data export |
| 1218P25 | 600326 | WTW Turb 430 T/Set-Portable; (90°, tungsten) acc. US EPA 180.1 incl. cal std kit in field case with table insert and acc. Cal.Kit, 4 empty cuvettes, cleaning tissues, screw driver, PC cable and instructions. Optional LabStation LSFlex/430 with software for GLP data export |
| 1218P26 | 600541 | WTW Ac. Kal.Kit P Turb 350IR; Calibration kit for turbidimeter Turb 350 IR, 0.02 – 10.0 – 100 – 1000 NTU, cleaning tissue and 4 indexing rings. |
| 1218P27 | 600542 | WTW Cal KalKit P Turb550/550IR; Calibration kit for turbidimeter Turb 550 and 550 IR 0.02 – 10.0 – 1000 NTU, cleaning tissues and indexing rings. |
| 1218P28 | 600543 | WTW Ac. Kal.Kit P Turb 555 IR; Calibration kit for turbidimeter Turb 555 IR 0.02 – 10.0 – 100 – 1750 NTU, cleaning tissues and indexing rings. |
| 1218P29 | 600544 | WTW Cal. Kal.Std P 10000NTU IR; Turbidity standard 10000 NTU for Turb 555 IR. |
| 1218P30 | 600545 | WTW Rg/Sol, Kal.Kit P Turb 555; Calibration kit for turbidimeter Turb 555, 0.02 – 10.0 – 100 – 1750 NTU, cleaning tissues and indexing rings. |
| 1218P31 | 600546 | WTW Cal, Kal.Std P 10000NTU WL; Turbidity standard 10000 NTU Turb 555 WL. |
| 1218P34 | 600560 | WTW Rea/Sol Kal.Kit Turb 430IR; Calibration standard kit for Turb® 430 IR 0.02-10-1000 NTU. |
| 1218P35 | 600561 | WTW Reag/Sol, Kal.Kit Turb430T; Calibration standard kit for Turb® 430 T 0.02-10-1000 NTU. |
| 1218P37 | 600601 | WTW Turb Acc., Cell Turb/SET; Empty cuvettes for laboratory turbidimeter Turb 550, Turb 550 IR, Turb 555 and Turb 555 (IR). Includes 3 pcs. |
| 1218P39 | 600603 | WTW Ac. Lamp Turb 550/555WL; Pre-adjusted spare lamp module (tungsten lamp), for turbidimeter Turb 550 and Turb 555. |
| 1218P40 | 600605 | WTW Turbidity Acc., Flow-Turb; Flow-through assembly for laboratory turbidimeters Turb 555 and Turb 555 (IR), for low pressure (1bar) applications. |
| 1218P41 | 600606 | WTW Turb Ac, Cell Turb 350/Set; Empty cuvettes for portable turbidimeter Turb 350 / 355 IR and 355 T. Includes 3 pcs. |
| 1218P42 | 600607 | WTW Turb Acc, Lamp Turb 550 IR; Pre-adjusted spare lamp module (IR) for Turb model 550 IR. |
| 1218P43 | 600608 | WTW Turb Acc, Lamp Turb 555 IR; Pre-adjusted spare lamp module (IR) for Turb model 555 IR. |
| 1218P44 | 251301 | WTW Turb BTLS Flex/430; LabStation for pHotoFlex® series and Turb 430 models for Lab use including software package for easy data import and export, rechargeable batteries and universal plug, RS 232 interface. |
