Instruction Manual

748213-S April 2002

Model 755R

2-2 CALIBRATION GAS REQUIREMENTS

WARNING

HIGH PRESSURE GAS CYLINDERS

Calibration gas cylinders are under pres- sure. Mishandling of gas cylinders could result in death, injury, or property damage. Handle and store cylinders with extreme caution and in accordance with the manu- facturer’s instructions. Refer to GENERAL PRECAUTIONS FOR HANDLING & STORING HIGH PRESSURE CYLINDERS, page P-4.

Analyzer calibration consists of establishing a zero calibration point and a span calibration point.

Zero calibration is performed on the range that will be used during sample analysis. In some applications, however, it may be desirable to perform span calibration on a range of higher sensitivity (i.e., more narrow span) and then jumper to the desired operating range. For example, if the operating range is to be 0 to 50% oxygen, span calibration may be performed on the 0 to 25% range to permit use of air as the span standard gas.

Recommendations on calibration gases for various operating ranges are tabulated in Table 3-1 (page 3-4) and are explained in Sections 2-2a (page 2-2) and 2-2b (page 2-2).

Each standard gas should be supplied from a cylinder equipped with dual-stage, metal diaphragm type pressure regulator, with output pressure adjustable from 0 to 50 psig (0 to 345 kPa).

Instrument response to most non-oxygen sample components is comparatively slight, but is not in all cases negligible. During initial installation of an instrument in a given appli- cation, effects of the background gas should be calculated to determine if any correction is required (See Section 3-4, page 3-1).

a.Zero Standard Gas

In the preferred calibration method, de- scribed in Section 3-4a (page 3-1), a suit- able zero standard gas is used to establish a calibration point at or near the lower range limit. Composition of the zero standard normally requires an oxy- gen-free zero gas, typically nitrogen.

b.Span Standard Gas

A suitable span standard gas is required to establish a calibration point at or near the upper range limit. If this range limit is 21% or 25% oxygen, the usual span standard gas is air (20.93% oxygen).

2-3 SAMPLE

Basic requirements for sample are:

1.A 2-micron particulate filter, inserted into the sample line immediately upstream from the analyzer inlet.

2.Provision for pressurizing the sample gas to provide flow through the analyzer.

3.Provision for selecting sample, zero stan- dard, or span standard gas for admission to the analyzer, and for measuring the flow of the selected gas.

a.Temperature Requirements

Sample temperature at the analyzer inlet should be in the range of 50°F to 150°F (10°C to 66°C).

Normally, however, a maximum entry temperature of 110°F (43°C) is recom- mended so that the sample temperature will rise during passage of the sample through the analyzer. This precaution prevents cooling of the sample and possi- ble analyzer-damaging condensation. With a thoroughly dry sample, entry tem- perature can be as high as 150°F (66°C) without affecting readout accuracy.

2-2

Installation

Rosemount Analytical Inc. A Division of Emerson Process Management