• Measuring ranges 0-0,1...1,6 Ext or 0-20...100% opacity
• Can be calibrated to mg/m3: 0-300...5000 mg/m3 per meter measuring distance
• For measurement of opacity installation without calibration
• Measuring path length: 0,5 - 14 m
• Automatic soiling correction, automatic zero and control point check.
• Typical applications: smoke density measurement in heating plants, dust concentration measurement in flue gas of Power plants, Steel and Blast Furnace Plants, Cement Plants, Refineries etc.
• Compliant to US EPA regulations

The instrument applies the 2-beam alternate light method following the autocollimation principle, i.e., the lightbeam crosses the measuring section twice. The unit measures and evaluates the light beam's weakening caused by the dust content within the measuring section.

Switching between the measuring beam and a comparator light beam proceeds through an electromagnetically actuated rotary diaphragm. For check value compensation, comparative measurings of 2 seconds duration each occur every 2 minutes. A photoelement alternatingly receives the measuring and the comparator light beam. There is only 1 joint amplifier for the measuring and the comparator beams, thus compensating for ageing of the bulb and the photo element, for temperature influences as well as for amplifier long-term drift. The monochromatic emitter light is being modulated with 1.2 kHz, avoiding influence of constant light (daylight, etc.). The core piece of the D-R 281 AV is a randomly programmable microprocessor. A 64" integral can be activated by way of a jumper in the terminal box. It works floatingly and effects a settled indication. There are 5 measuring ranges switchable between 0.1, -0.2, -0.4, -0.8, -1.6 ext.

For proper functioning the D-R 280 performs a check cycle every 2 hours, thereby measuring and indicating the zero point, the soiling of the optical boundary surfaces as well as a reference value automatically. If necessary, the subsequent measuring values will be corrected. If the correction surpasses a determinated value, an error signal will be generated.

The DURAG D-R 281 AV Dust Concentration Meter is used for continuous dust measuring in flue gas chimneys and dust extraction pipings. According to TA Luft and 13. BlmSchV it is suitable for

furnace plants with hard coal, brown coal, fuel oil and mix-type combustions

converter plants, asphalt mixing plants and cement production plants

as well as for any other type of plant requiring quantitative measuring of dust concentrations.

Type tested to the guidelines for emission measuring equipments of the Federal Ministry of Interior - FMI Circular UII 8-556134/4 dated 21.7.1980

by TÜV Rheinland Technical Ins-pection Agency, Test Report # 936/802002-2 of 10.12.82,

itemized in the list of suitable instruments for continuous registration of emissions. Joint Ga-zette # 16 of 15.6.1983 of the Federal Ministry of Interior.