Model 755A

Instruction Manual

245364-V May 2002

2.A zero-suppressed range uses a blend consisting of a suitable percentage of oxygen contained in a background gas, typically nitrogen.

The upscale standard gas is required to establish a calibration point at or near the upper range limit. For example, if this

range limit is 21% (or somewhat greater than 21%), the usual upscale standard gas is dry air (20.93% oxygen).

Typical examples of standard gases for recorder oxygen ranges are shown in Table 3-2, page 3-6.

A. TYPICAL ZERO-BASED RANGES

0 to 1

Nitrogen

0.9% O2

Balance N2

0 to 10

Nitrogen

9% O2

Balance N2

0 to 100

Nitrogen

100% O2

 

B. TYPICAL ZERO-SUPPRESSED RANGES

RANGE

 

RECOMMENDED STANDARD GAS

RECOMMENDED UPSCALE

% O2

 

STANDARD GAS

 

 

 

20 to 21

20.2%

±0.2%

O2

Air (20.93% O2)

11 to 21

11.2%

±0.2%

O2 Balance N2

Air (20.93% O2)

99 to 100

High Purity O2 with 0.8% ±0.05% High Purity N2

High Purity O2

90 to 100

91% ±0.5% O2 Balance N2

High Purity O2

Table 3-1. Standard Gases Recommended for Calibration of Various Oxygen Ranges on Analog Output

Rosemount Analytical Inc. A Division of Emerson Process Management

Operation 3-5