Gas Purity; Traps; Purity Requirements - Thermo Scientific FOCUS GC Site Preparation And Installation Manual

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Gas and Plumbing Requirements

Gas Purity

If possible, you should use only instrument or chromatographic purity grade gases

in your FOCUS GC.

UHP (Ultra-High Purity) gases should not contain impurities above 1 ppm.

Impurities below 1 ppm generally do not require purification. Gases with higher

impurity levels may require oxygen and hydrocarbon traps. A number of GC

supply and accessory companies carry a variety of traps for gases.

See Figure 4-2,

sequence. For more information on gas purification, contact your local Thermo

Fisher Scientific CSE.

Moisture Traps

Water in the carrier or fuel gas may damage the gas chromatograph column and

contaminate the FOCUS GC system. Water content should be less than 1 ppm in

all cases. If you are using multiple traps, install the moisture trap closest the gas

supply, before the hydrocarbon and the oxygen trap.

Hydrocarbon Traps

Hydrocarbon traps remove organic materials from gases. If you are using multiple

traps, install the hydrocarbon trap after the moisture trap, but before the oxygen

trap.

Oxygen Traps

Oxygen content in the carrier and gas lines should be less than 1 ppm. To achieve

a level of oxygen of less than 1 ppm, install an oxygen-removing trap in the

carrier gas line between the gas tank and the GC. If you are using multiple traps,

the oxygen trap should be the last trap in the series.

The following sections describe the minimum requirements for gases used in your

gas chromatograph system. Always consider using UHP 99.999% pure gases

when available.

Site Preparation and Installation Manual

Gas Trap

Order, on page 57, for the correct trap installation

Chapter 1

Laboratory Preparation

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