Instruction Manual

748332-F April 2003

Model NGA2000 NDIR

2-3 LOCATION

Install the NDIR Analyzer Module in a clean, non-hazardous, weather protected, vibration free location free from extreme temperature variations. For best results, install the instrument near the sample stream to minimize sample transport time. Operating ambient temperature is 0oC to 45oC (32oF to 113oF). Sample dewpoint is 40°C or less.

NOTE

Unrestricted air flow in the rear of the Analyzer Module is critical to its performance and reliability..

2-4 GAS SPECIFICATIONS

a.Calibration Gases

All applications require a zero standard gas to set the zero point on the display and external data acquisition devices. if the factory provided Calibration and Data Sheet (in the rear of the manual) specifies a background gas, use this as a zero gas. If a background gas is not specified, use dry nitrogen.

negated if the same flow rate is used for sample, zero and span gases. But, if flow is high enough to cause elevated pressure, careful control (tighter tolerance) of flow rate is required to avoid errors.

If flow is kept at or below 2 SCFH (1 L/min), sample and instrument temperatures reach equilibrium regardless of stream temperature (within specifications; 0 to

55°C). At extremely high flow rates, this may not be true, although no such effect has been noted up to 18 SCFH (9 L/min).

See Table 2-1 on page 2-3 for cell purging times at atmospheric sample pressure.

c.Sample Pressure/Filtration

Sample should be introduced to the Analyzer Module at a maximum 690 hPa- gauge (10 psig). Pressurized applications are available, which require pressurized cells and careful control of flow rates, consult factory for these applications. Sample should be filtered for particulates down to two microns.

d.Leak Test

Span gas should be between 75% and

The Analyzer Module is completely tested

100% of fullscale span. Flowing reference

at the factory for gas leakage. The user is

(if used) should be dry nitrogen.

responsible for testing for leakage only at

 

the inlet and outlet fittings on the rear panel.

 

The user is also responsible for internal leak

b. Flow Rate

testing periodically and if any internal

Recommended sample flow rate is 1 to 2

pneumatic components are adjusted or

replaced (with a test procedure chosen by

SCFH (500 TO 1000 cc/min). A lower flow

the user).

rate will not affect readings but may result in

 

an undesirable time lag. Excessive flow

 

can produce increases cell pressurization

2-5 GAS CONNECTIONS

and reading error.

 

(See Figure 2-2 on page 2-3) Connect inlet

At higher cell pressures, the nonlinearity of

and outlet lines for sample/zero/span and

the calibration curve increases. Therefore,

flowing reference (if applicable) to

the calibration curve should be redrawn for

appropriately labeled fittings on the rear

higher flow rates. Also, the effect of

panel. All four connections are 1/4 inch

increased cell pressurization can be

ferrule-type compression fittings.

2-2 Installation

Rosemount Analytical Inc. A Division of Emerson Process Management