SediMeter™ model SM3B
This is the same instrument as the SM3A, but with a built-in cleaner intended to keep the sensor free from biofouling. A motor in the top drives a cleaner shuttle hanging in a thin but strong line outside the instrument. The motor house is made of copper-nickel, an alloy with very low corrosion and excellent natural anti-fouling characteristics. Approximately 50 cleanings can be made on one battery charge. The cleaning interval is set as a multiple of the measurement interval. Another difference is that it has the connector in the lower end instead of in the upper end.
This model is recommended where biofouling is a significant problem, but not where suspended sand is present in the water column. Consider the SM3C version in such cases. If you require real-time monitoring in the lab, consider the SM3A or SM3C models, since they have the cable connection in the top end. Another reason to select this instrument can be the battery capacity, which is several times larger than the other models.
Features in common for all SM3 models of 2017:
The sensor consists of 36 near infrared optical backscatter detectors (NIR OBS) spaced 1 cm apart. The active measurement length is 35 cm. Turbidity is measured at 71 levels, every second one as straight backscatter and avery second one as oblique backscatter, and reported in formazin turbidity units (FTU) with no decimals. The level is estimated with 0.01 mm resolution.
There is an identical optical backscatter detector located 11 cm above the others. It is used to measure straight backscatter turbidity as a separate variable. The instrument also reports temperature and battery level at each measurement.
Burst samples of up to 20 samples of turbidity and level can be taken in each measurement, with a time interval of 1 s to 16 s between the burst samples. This allows for detecting differences during a wave period, for instance. The time interval between measurements is from 3 seconds to 24 hours.
The SediMeter has a built-in memory that holds 16,384 measurements. It can also be used in real-time monitoring, alone or in a network. When used in stand-alone mode it is powered by a built-in battery that is recharged through the same USB cable used to set up the instrument and to download data.
The instrument can be mounted in sediment using the standard anchor and holder tube included if purchasing a kit. This holder is screwed down in mud and sand with the help of a handle.
The instrument is available separately or as a kit in a convenient case, complete with all necessary accessories for stand-alone use in the field (handle, anchor, holder tube, cable, blind plug).