Envco – Environmental Equipment

Measures the Bottom with a Unique, Patented Sensor
• Sedimentation
• Accumulation
• Deposition
• Erosion
• Scour
• Siltation
• Turbidity
• Resuspension
• Light*
• Pressure* (tides, waves)
• Stand-Alone Mode
• Real-Time Mode
• RS-485 Network
• Software Included
• Supports internet web server

For environmental monitoring of coral reefs, fish farms, dredging, etc

The SediMeter™ is designed for detecting minute changes in bottom elevation. It can be used for monitoring the accumulation of sediments, and resuspension of gyttja.

The sensor consists of an array of 36 infrared optical backscatter detectors. The turbidity is measured every 10 mm, and the bottom level estimated to 0.1 mm.

This totally redesigned SediMeter™ offers optional sensors for pressure and visible light. Temperature with 0.01ºC resolution is standard.

The SediMeter™ comes with a computer software for setup, download, data analysis, and real-time monitoring of a network of hundreds of SediMeters. Furthermore, it can act as a web server so the monitoring can be supervised from the internet.

Optional Sensors include
Optional pressure and light sensors can be sampled up to 84 times per measurement, with a user-selectable frequency. Wave periods can be estimated from these data.

Light Sensor - Visible Light The light sensor is a factory installed option on top of the SediMeter. The sensor is mounted inside a transparent cone, to avoid sedimentation over it. As default it measures light in a linear scale from ca 100 lux to 178 klx. This is quivalent to the range from a livingroom to bright sunlight. The LogDator allows the sensor to be sampled up to 84 times per measurement, with a rate varying from 0.5 Hz to 400 Hz. Each value is measured with ca 44 lux resolution, 16 times per sample, and reported with ca 2.7 lux resolution.

Pressure Sensor - Depth Meter
The pressure sensor measures the absolute pressure down to 24 m depth. It may be used to monitor the tide, but also for waves, since the LogDator allows the sensor to be sampled up to 84 times per measurement with a rate varying from 0.5 Hz to 400 Hz. The SediMeter software can then estimate the wave parameters. The sensor is made from stainless steel. NB: This sensor requires an optional longer plug (LM-03-01-B) since it is mounted on the side, not on the top, to avoid sedimentation on its pressure port.

SediMeter SM2 (all models)
Weight in air Ca 0.5 kg (1 lb.)
Weight in sea water Nearly neutral
Depth rating 45 m (150')
Dimensions 700 mm x 51 mm excluding holder (27.6" x 2")

Sensor
Active sensor length 350 mm (13.8")
Detectors per sensor 36
Detector spacing 10.0 mm
Turbidity resolution Last bit ca 0.3 FBU, nominally
Turbidity accuracy, std mounting ca ±100 FBU
Turbidity accuracy, no outer tube ca ±6 FBU
LED wavelength 945 nm
PCODE 63682 (turbidity sensor classification in the USGS National Water Information System, NWIS)

LogDator™
Function A programmable low-power measurement computer
Sampling frequency User selectable from 1 second to 24 hours
Real-time clock Can be set to within 0.02 s; by default uses UTC
Diver interface Magnetic switch available for customizable diver operation
Built-in sensor Temperature
Optional sensors Pressure; incident visible light
Optional sensor sampling Bursts of 0 to 84 samples at 0.5 Hz to 400 Hz
Power backup Keeps settings during several minutes without batteries

SediMeter software
Communication protocols USB and RS-485
File import *.ld2 files written by the LogDator™ on memory cards
Functions, logging Instrument setup; data download, presentation, analysis, export
Functions, real-time Control 1 to 255 networked SediMeters; data presentation locally & web server
Resolution, level 0.1 mm
Linearity without calibration 1 mm
Pressure and light analysis Average, frequency, wave height estimate

Model 2A specific
Overview Same as 2B, plus MMC and SD cards for added data storage and data retrieval without need for field PC
Internal memory 2 MB
Storage capacity 4096 records internally
Removable memory MMC and SD cards
Memory card 128 MB card holds 6 months of data at one measurement per minute
Card data retrieval Put the card in a computer and import the *.sd2 file using the SediMeter software
User interface "NavPin" LCD display and control stick for setting up without computer
Communication protocols USB, RS-485
Communication features Set-up, download, real-time measurements
Measurement network RS-485 network capable with up to 255 instruments on one cable, guaranteed to work with 1200 m cable
Batteries 2 size AA 3.6 V Lithium batteries 2.7 Ah (included)
Battery lifetime From a few weeks to many years depending on sampling rate, sensors, and memory card
Case Water-tight storage and transportation case with wheels

The SediMeter reports turbidity in the unit FBU. It is a kind of Formazin Turbidity Units (FTU), similar to the ISO 7027 standard of FNU (Formazin Nephelometric Units). The difference is that the scattered light is measured at 180 degrees rather than 90 degrees, and that the near infrared (NIR) wavelength is 945 nm rather than 860 nm. The somewhat longer wavelength helps decrease the influence of ambient light, as does a new measuring and compensation procedure. The ISO standard (as well as the US standard, NTU) of 90 degree scatter is incompatible with measuring very high concentrations—they would report low concentration values rather than high when buried.

About power demand
Power supply options Batteries, USB, RS-485 cable
Multiple power sources at once The one with the highest voltage is used
Absolute maximum voltage 9 V
Minimum voltage for measurement 5.5 V
Minimum operational voltage 3.0 V
Minimum RAM retention voltage 1.8 V
Current consumption w/o card RS485 mode: 0.83 mA in idle, log mode: 0.032 mA, sleep mode: 0.032 mA
Current consumption of card A typical MMC or SD card uses 0.10 mA to 0.25 mA in idle (not guaranteed)
Batteries Two 3.6 V Li size AA (not 1.5 V!)
USB 5 V power For setup and download, not measurements
RS-485 user-supplied power 5.5 V < U < 8.8 V
Capacitor backup power Several minutes when switching batteries (display off, sleep mode