The sample volume being tested regulates the amount of oxygen available for a complete BOD measurement.  BOD measurement ranges of up to 4,000 mg/l can be measured using different sample volumes.

The OxiTop® BOD instrumentation heads (green and yellow for differentiation of inflow/outflow) have an AutoTemp function: if the sample temperature is too cold, the start of BOD measurement is automatically delayed (by at least 1 hour) until a constant temperature has been reached.

Apart from the automatic storage of 5 measured values (1 value per day), further measured BOD values can be read at all times during or after the period of 5 days, which permits the tracking of check values or measurements over longer periods.  The OxiTop BOD Instrumentation measurement system also offers simple operation, improved controllability, and non-toxicity.

OxiTop Control 6, Control 12
OxiTop® Control Biological Oxygen Demand (BOD) Instrumentation is an advanced version of the successful OxiTop® BOD Instrumentation system that uses software-controlled functions and an infrared interface to communicate with a handy controller, the OC 100.  This BOD instrumentation system enables the simultaneous and grouped start, management, storage and tracking of 100 BOD measuring heads via the controller and allows them to be tracked on a large display with graphic evaluation.  BOD measurement data can be transferred to the PC for evaluation and documentation via the AK-540/B cable (order no. 902842) and the communication program Achat OC (order no. 208990).

The Biological Oxygen Demand (BOD) data can be called up at any time, even during sampling, thus enabling checking of the samples for errors.  The display of the progress curve allows immediate detection of irregularities and interferences, such as having the BOD value set too high for the volume used or undesired nitrification.  BOD measurement corrections can thus be made at an early stage.  OxiTop® Control BOD instrumentation offers you simple operation, improved controllability, non-toxicity, and measuring ranges of up to 4,000 mg/l BOD.

Biological Oxygen Demand Measurements according to EN 1899-1 and EN 1899-2 and for self-checks
Biological oxygen demand (BOD) determination is still one of the most important parameters in water resource management.  BOD measurements can be used to evaluate the impact of biodegradable substances in waters and wastewater by measureing the quality of water and treatment results in wastewater.  In addition, BOD instrumentation measurments are used in the planning and design of wastewater treatment facilities.  The OxiTop® BOD measurement instrumentation system offers a unique, modular and mercury-free way to make BOD measurements.  It is not only suitable for BOD determination, but also for measuring biodegradability and depletion.

In routine use, BOD determination is used to check the wastewater in the inflow and discharge of wastewater treatment plants.  Depending on the measurement site and type of wastewater the BOD value can lie between a few mg/l and several thousand mg/l.  Several BOD testing methods are available for carrying out the measurement.

Various systems for BOD determination methods
In “dilution BOD” the oxygen content of a sample is measured with an oxygen sensor before and after an incubation period of 5 days.  The difference between the measurements is the BOD5 value; this is the official EPA BOD measurement method.  The Oxi 1970i Portable Dissolved Oxygen Meters can be used for dilution BOD measurments.

In “BOD self-checks” with the respirometer the reduction in oxygen causes a definite pressure difference which can be measured by a pressure sensor.  This BOD measurement method is very easy and practical to carry out.

Although both methods are very different, the BOD measurements correlate for discharge analysis in municipal wastewater treatment facilities.  Both BOD measurement methods require that the samples to be kept at 68 °F (20 °C) for 5 days.  WTW offers a temperature controlled box for use with the Oxitop® BOD instrumentation system.

BOD Instrumentation Specifications

OxiTop IS
Measuring principle: Respirometric (manometric)
Display: 2-digit 7-segment LED, 10 mm
Measured parameter: Digits
Measuring range: 0 to 40 digits (+10 digits for overranging)
Accuracy: + 0.03 psi (+ 2 hPa) or + 1 digit
Admissible measuring temperature: 68°F ± 1.8°F (20°C ± 1°C)
Admissible sample temperature (when being filled): 59-68°F (15-20°C)
Power supply: Lithium batteries (260 mAh), 2 x type CR 2430 (3V)
Power consumption: Max. 25 mA (during measurement)
Battery run time: ~ 3 years with normal use
Protection class: 3 IEC 1010
Protection system: IP 54 IEC 529
EMC
     Emissions: EN 50081-1, FCC Class A
     Immunity: EN 50082-2, NAMUR recommendation
Climate class: 2, VDI/VDE 3540
Ambient temperature:
     Storage: -13°F to +149°F (-25°C to +65°C)
     Operation: 68°F ± 1.8 F (20°C ± 1 C)
Test mark: CE
Dimensions: H: 2.7in, dia. 2.8in (69 mm, dia. 70 mm)
Weight: Approx. 3 oz. (85 g)

OxiTop -C
Measuring principle: Respirometric (manometric)
Measured of: BOD_n (oxygen drift according to DIN 38409 T 52)
Pressure range: 7.25 to 19.5 psi (500 to 1350 hPa(mbar))
Accuracy: + 1% of measured value, + 7% of measuring range
Resolution: 0.015 psi (1 hPa)
Display: LED pilot lamps
Power supply: Lithium batteries (260 mAh), 2 x type CR 2430 (3V)
Battery run time: ~ 2 years with normal use
Protection class: 3 IEC 1010, EN61010 part 1
Protection type: IP 54 DIN 40050
Admissible measuring temperature: 68°F ± 1.8 F (20°C ± 1 C)
Admissible sample temperature (when being filled): 59-68°F (15-20°C)
EMC
     Emissions: EN 50081-1, FCC Class A
     Immunity: EN 50082-2
Climate class: 2, VDI/VDE 3540
Ambient temperature:
     Storage: -13°F to +149°F (-25°C to +65°C)
     Operation: 41°F to 122°F (5°C to +50°C)
Test mark: CE, UL, CUL(UL/CSA)
Dimensions: H: 2.8in, dia. 2.8in (70 mm, dia. 70 mm)
Weight: Approx. 3.4 oz. (95 g)

OC 100 BOD Instrumentation Controller
Data sets per measurement: 180 to 360 (depending on duration)
Measurement period: 0.5 hr to 99 days
Power supply: 3 AA batteries; alkaline 1.5V
Interface: IR (infrared); RS 232 for communications with PC
Ambient temperature:
     Storage: -13°F to +149°F (-25°C to +65°C)
     Operation: 41°F to 104°F (5°C to +40°C)
Dimensions (HxWxD): 1.7x3.9x7.9 in (45x100x200 mm)
Weight: Approx. 13.8 oz. (390 g)

BOD Instrumentation Magnetic Stirrer
Power supply:
     Input: 230 VAC (+10%/-15%) 50/60 Hz /24 VA
     Output: 18 VAC / 1 A
Power consumption: 24 VA max.
Speed of the stirring rods: Program-controlled 180 to 450 min^-1
Instrument protection class: 3, IEC 1010, IP30
EMC
     Emissions: EN50081-1/FCC class A
     Immunity: EN50082-1, EN50082-2, Namur
Climate class: 2, VDI/VDE 3540
Ambient temperature:
     Storage: -13°F to +149°F (-25°C to +65°C)
     Operation: 41°F to +104°F (+5°C to +40°C)
Relative humidity:
     Yearly mean: < 75 %
     30 days/year: < 95 %
     Remaining days: < 85 %
Test mark: CE, UL, CSA
Dimensions (LxWxH):
     IS 6: 10.5x7.25x2.75 in (265x181x67 mm)
     IS 12: 13.75x10.5x2.75 in (350x266x67 mm)
Weight (inclusive line adaptor):
     IS 6: 3.5 lbs (1.6 kg)
     IS 12: 7 lbs (3.2 kg)