McNab Model AP-VI SD Stack Opacity Monitor/Controller

Interior of Unit

Features:

• High reliability
• Easy installation
• Low maintenance
• Long-term stability
• Self-correcting optics
• No fine alignment

Use for:

• Power Plants
• Refineries
• Smelters
• Arc Furnaces
• Waste Burners
• Diesel Generators
• Incinerators

Related Technical Papers/News Releases:

• Stack monitoring system operates under ambient temperature conditions exceeding 140º F

Model AP-VI SD

If you must continuously monitor the density of particles passing through a smoke stack or an exhaust duct, the McNab Optical Products Model AP-VI SD opacity monitor/controller should be your instrument of first choice.  Here's why:

Easy Installation

All that is required are two holes on opposite side of the smoke or exhaust stack fitted with flanged nipples. Stacks up to 75 inches in diameter can be accommodated. The light source assembly is bolted to the flange on one side of the stack; the photo-cell scanner assembly to the other; no obstructing sampling devices are placed in the stack.  When required, a source of instrument clean air is connected to both assemblies to continuously purge optical elements of contaminants.  No focusing is required.

Minimal Maintenance

A unique laminar-flow air-sweep system keeps optical elements clean and clear for a minimum of three months between cleanings.  Wing-nut clamps permit easy removal of optical modules for cleaning.

High Reliability

Advanced electronic circuitry permits use of minimal optical surfaces, further reducing need for periodic cleaning. Optical surfaces have been reduced by 50 per cent for increased reliability.

Long-Term Stability

Self-correcting optics provide long-term stability.  The graph below compares the opacity of a McNab Model AP-VI SD over a 14-hour period with that of a typical competitive unit under actual and identical operating conditions.  Note that the competitive unit would have to be cleaned every six hours to prevent false readings. The McNab unit remains accurate throughout the period and would continue to do so for months to come, thanks to its unique air-sweep system.

Factory Focused

The light source and the photo-cell scanner are optically pre-focused individually and together at the McNab factory so a field optical technician is not required for installation or operation.  A clear stack gives a 0 Ringelmann (0 per cent opacity) reading, and a totally opaque stack gives a 5 Ringelmann (100 per cent opacity) reading.  Field focusing is not needed.  Electronic control circuitry keeps the intensity of the light source uniform throughout lamp life. For those who require periodic calibration records, McNab can supply kits of calibrated, graduated glass optical filters with known smoke-density ratings.

Optional Output Devices

McNab can supply output devices to meet your particular requirements. Simplest are panel assemblies, AP-VI SD, with meters and repeater relays which provide alarm contact closures (rated at 5A @ 230V).  Where environmental regulations require continuous records, strip chart recorders, AP-IIl SD, can be provided.

Specifications

A89-42c