Model 755A

Instruction Manual

245364-V May 2002

Example:

Sample is oxygen in a background of CO2. (Oxygen equivalent of CO2 is - 0.623).

Standard is the following:

Pure nitrogen for ZERO gas.

21% oxygen, 79% nitrogen for SPAN gas. (Oxygen equivalent of nitrogen is -0.358).

With nitrogen ZERO gas flowing, Adjusted Value is the following:

0 0 + 100 [100((-0.623)-(-0.358))]-100((-0.623)-(-0.358))

100

0-100(-0.265)

= 0.265

100

 

Display should be made to read 0.265% oxygen with ZERO control.

With SPAN gas (21% oxygen, 79% nitrogen) flowing, Adjusted Value is the following:

 

21

[100((-0.623)-(-0.358))]-100((-0.623)-(-0.358))

21+

100

 

 

 

100

 

 

 

 

 

 

 

0-211(-26.5)-(-26.5)

 

-5.565+26.5

 

21+

 

=

21 +

 

 

= 21.21%

 

100

 

 

100

 

 

Display should be made to read 21.21% oxygen with SPAN control.

In limiting cases the general equation reduces to simpler forms:

1.If the SPAN gas is 100% oxygen, there is no background gas and thus no correction.

2.If the ZERO gas is oxygen-free, the adjusted value for setting the ZERO control becomes -((-0.623)-(-0.358)). When the ZERO gas is more diamagnetic than the background gas in the sample, this difference is negative. Use a recorder with below- zero capability to set negative values.

 

GAS

EQUIV. % AS O2

 

Acetylene, C2H2

-0.612

 

Allene, C3H4

-0.744

 

Ammonia, NH3

-0.479

 

Argon, A

-0.569

 

Bromine, Br2

-1.83

 

1,2-Butadiene C4H6

-1.047

 

1,3-Butadiene C4H6

-1.944

 

n-Butane, C4H10

-1.481

 

iso-Butane, C4H10

-1.485

 

Butene-1, C4H8

-1.205

 

cis Butene-2, C4H8

-1.252

 

iso-Butene, C4H8

-1.201

=

trans butene-2, C4H8

-1.274

Carbon Dioxide CO2

-0.623

 

Carbon Monoxide, CO

-0.354

 

Ethane, C2H6

-0.789

 

Ethylene, C2H4

-0.553

 

Helium, He

-0.059

 

n-Heptane, C7H16

-2.508

 

n-Hexane, C6H12

-2.175

 

cyclo-Hexane, C6H12

-1.915

 

Hydrogen, H2

-0.117

 

Hydrogen Bromide, Hbr

-0.968

=

Hydrogen Chloride, HC1

-0.651

 

Hydrogen Fluoride, HF

-0.253

 

Hydrogen Iodide, HI

-1.403

 

Hydrogen Sulphide, C2S

-0.751

 

Kryton, Kr

-0.853

 

Methane, CH4

-0.512

 

Neon, Ne

-0.205

 

Nitric Oxide, NO

+44.2

 

Nitrogen, N2

-0.358

 

Nitrogen Dioxide, NO2

+28.7

 

n-Octane, C8H18

-2.840

 

Oxygen, O2

+100.0

 

n-Pentane, C5H12

-1.810

 

iso-Pentane, C5H12

-1.853

 

neo-Pentane, C5H12

-1.853

 

Propane, C3H8

-1.135

 

Propylene, C3H6

-0.903

 

Water, H2O

-0.381

 

Xenon, Xe

-1.340

Table 3-3.Oxygen Equivalents of Common Gases

Rosemount Analytical Inc. A Division of Emerson Process Management

Operation 3-11