McNab Model KSA Near-Infrared Direct Reading Process Analyzer

product_KSA_cover.JPG (71061 bytes)

For continuous, real-time and unattended monitoring of chemical concentration in the process environment.

KSA Analyzers: From 200 to 2,500 nm

Related Technical Papers/News Releases:

Modular Optical Cell

  • Quick window removal, cleaning and replacement; solves solids build-up and other "window problems”
  • Rugged design is ultra-sealed to prevent moisture migration.
  • Replacement caps allow line to operate without cells installed. 
  • "Robust" equipment

How it Works

product_KSA_diagram.JPG (52274 bytes)Consisting of a flow cell unit, two modular optical cells: one for the NIR-UV radiation source, the other for the scanner; and an indicator/controller cabinet, the KSA family of concentration analyzer systems continuously monitor chemical concentration by direct across-the-pipe measurement of absorption peaks in the production/quality control environment.

McNab fixed-filter KSA instruments measure the change in radiation received from the NIR-UV source to the scanner photocell detecting unit.  These signals are transmitted to an indicator/controller unit that contains the electronic circuitry necessary to process the signals, to display the readings, to input desired set points, to indicate alarm levels and to operate alarm relays.  It also has continuous output for proportional control connections.

The Model KSA uses the very latest optical technologies to provide stable, low-noise signals across the NIR range.  Collimated NIR-UV radiation is directed through the process fluid stream to the detector unit that generates electrical signals. These signals are preamplified and sent to the indicator/controller cabinet, which compares the NIR-UV signatures with those for which the KSA has been calibrated.  The ratio of the NIR-UV signature and the background process fluid signal is calculated, allowing the instrument to instantly self-correct for changes in the fluid stream caused by such items as color, turbidity or window fouling.

As the flow cell unit is pipe-mounted, the KSA provides immediate across-the-pipe measurements at operational pressures and temperatures. Distortions caused by sample temperature and/or pressure changes are avoided, as are other compromises normally required of off-line sample lines or with laboratory analysis.

The across-the-pipe optical path can he visually inspected any time during operation without pipe shutdown, and McNab’s unique modular optical cells can he quickly hand-removed for off-line inspection, pressure test or replacement. This design has eliminated the traditional problem of broken window glass and fogging.

Unambiguous calibration is accomplished via the built-in calibration slot in the scanner housing.

From Ultraviolet to Near-Infrared

Model KSA spectroscopic analyzers measure chemical concentration in process liquids with:

  • Automatic calculation for direct concentration readings

  • Self-correcting optics and electronics

  • Time proven design; thousands of modular optical cells installed since 1960

  • Selectable path lengths

  • In-pipe span calibration using reference filters without flow interruption

Model KSA instruments utilize a unique calibration method that allows simple verification without flow interruption.  Such in-process verification offers great savings in terms of time and expenses related to flow interruption, line dewatering and sensor disconnection; and because the pipe is never opened, hazardous or sterile conditions are nor compromised.

Calibration may be accomplished using a standard reference optical filter cartridge, which offers reliable analyzer testing for its quality assurance documentation (ISO 9000 and others.)

product_KSA_diagram_field_calibration.JPG (31379 bytes)In Figure 1 below, the vertical axis represents the optical density of the cartridge; the horizontal axis shows the resultant KSA meter reading. The readings verify the KSA's accurate operations.

Advanced Optical And Electronic Design Provides Greater Range

The KSA's electronics have been specially designed so that the digital meter readings can be adjusted to fit parts-per-million (ppm) units following the Lambert-Beer Law of optics, as:

M = A = ELC,

where M = Meter Reading

A = Absorption

E = Extinction coefficient of substance

L = Sample path length within pipe

C = Concentration (in PPM)

Modular Optical Cell

product_KSA_modular_optical_cell.JPG (20170 bytes)The KSA flow cell assembly  consisting of the flow cell unit and two head assemblies houses the sensor detector, electronics and McNab’s exclusive modular optical cells.

The modular optical cell includes the pressure seal, window, collimating optics, air purge vent and a unique 4-gasket sealing system that prevents moisture migration into electrical conduits; protecting against false readings and preventing equipment damage.

McNab’s modular optical cells contain all the elements that may he optically degraded or severely coated by the process, e.g., windows and gaskets. The optical cells may he removed, cleaned and reinstalled in less than five minutes, avoiding long down-times and costly delays associated with spool-piece removal.

A temporary quick-removal cap allows the process line to operate while the modular optical cells are removed.

Other Photometric Instruments

The KSA is factory-customized to spectroscopically measure specific chemical concentrations based on their near-infrared or ultraviolet signatures. Other McNab instrumentation is available to provide photometric analysis of such items as turbidity – using monitors that measure with nephelometric (scatter) and forward-scatter technologies for the measurement of low-level turbidities (NTU, PPM, EBC, etc.) – as well as color, high-level chemical concentration, optical density and others.  Contact McNab for more information.

About McNab 

McNab, Inc. is located in metropolitan New York City. Our offices in Mount Vernon, New York include our research & development laboratory, design engineering department, modern manufacturing plant and automatic testing facilites to evaluate our products.  McNab's Quality Assurance Process meets Mil-I-45208.  We also maintain an engineering and parts facility in Europe.


Model KSA
Principle of Operation: Direct-reading spectroscopic comparison of intensity of NIR/VIS/UV radiation before and after it has passed through a liquid.

Attenuation of radiation as a measurement of change of chemical concentration.

Specifications: Contact McNab for specific technical notes.
Range and Units: 200 - 2,500 nM in customer-specified units.
Ambient Conditions: -10° - 158° F (-23° - 70° C), 0-100% relative humidity
Recorder Output: 0-1 mA or 0-0.1, 10 V
4-20 Output: Two-wire, ground isolated powered (channel 1).  Two wire, unpowered for computer (channel 2)
Alarms: Two independent adjustable set-point alarms with warning of NIR-UV source failure/obscured lenses/power loss.  SP/DT 5A resistive, unpowered contacts.
Power Requirements: 115/230 VAC, 50/60 Hz switch selectable, 75 Watts max.
Housing: NEMA 4 (Watertight), 4X (stainless), hinged door 13"W x 16"H x 7 1/2"D; (33 x 41 x 18 cm) for wall mounting.
Weight: 25 lb./11.3kg.
Flow Cell Assembly (available separately)
Range: Follows indicator.
Style: Standard or sanitary designs.
Optics: Four-filter method.
Light Path: Appropriate to absorption level.
Material: Stainless steel, ASTM 316L/DIN 4435, others available.
Windows: Vitreous silica.  Other material as required.
Seals: Gaskets to match process.
Detector: Instantaneous Four-diode typical; photo conductive as required.
Flow Chamber
Specifications: Unrestricted, full-diameter flow or to suit application.
Operating Pressure: 150 psig, 10 bar, PN 10. (Contact factory for higher ratings).
Operating Temperature: -10° - 225° F (-23° - 115° C).  For up to 480° F (250° C) contact factory.
Enclosures: NEMA 6 (submersible), IP68.
Separation from Indicator 250 ft. (75 meters).
System Calibration: Permanent reference filter.
Accessories: Extensive users manual, regulated power supply.
Service: Commissioning, preventive maintenance, and filter selection laboratory work-up.
Specifications may be changed or improved as necessary.

383-2 East 29th Street | Buena Vista, VA | USA 24416-1293

540.261.1045 voice | 540.261.1268 fax |

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