ALD Holcroft Acetylene Based Vacuum Carburizing

Acetylene

Acetylene

Acetylene

Dissociation MechanismAcetylene (C2H2)

Hydrocarbon

Heat

C (ad) 2H (ad)

H2 (gas)

Carbon Diffusion

Steel Surface

+

+

Acetylene

Dissociation Products

Typical Dissociation Products

Average Carbon Flux. g/m2h

Acetylene C2H2 2C + H2 150

Methane CH4 2H2 + C <5

Ethylene C2H4 CH4 + C 120

Propane C3H8 CXHY + C + H2 130

Cyclohexane C6H12 CXHY + C + H2 N/A

Dissociation Potential

Acetylene

Purity ComparisonAnalyzing trace metals,

glass mold release Welders Grade

Chemical Acetylene

Atomic Adsorption Grade Acetylene

Industrial Acetylene

Typical Assay 99.2% 99.6% 98.0%

Ammonia None 50 ppm max

Hydrogen Sulfide None Not reported

Phosphine None <20 500 ppm max

Ethylene <5,000 ppm max None

Methane <2,000 ppm max None

Ethane <500 ppm max None

Oxygen + Methane <4,000

Other Hydrocarbons <500 ppm max None

Other Contaminants None 1.95%

Acetone <1,000 ppm max Dissolved in Acetone Dissolved in Acetone

Acetylene

Today’s Acetylene

Chemical Acetylene:

• Produced as a by-product of the ethylene production process

• Higher overall purity

• More consistent in its composition

• Dissolved in dymethyl formamide (DMF), not acetone• Acetone is volatile and “carries through” with the acetylene• Acetone vapors can be a cause of sooting• Acetone can react with certain rubber compounds (valve seats, seals, etc)

• Reduces unwanted atmosphere constituents

• Highest level of reproducibility

Data provided by:Bob Esper of Praxair

Acetylene

Reactive, colorless, highly flammable gas.

Available as gas dissolved in liquid

– Through IG companies or distributors– Generally supplied in cylinders or bulk trailers– Stored in solution, under pressure– Chemical acetylene v industrial acetylene– Chemical acetylene is a co-product derived from the thermal

cracking process used to produce ethylene.

Purity Specification…

Characteristics

Acetylene

Size: 8 feet wide by 40 feet long Gross Weight (full): 80,000 pounds Configuration: 200 - 390 cf acetylene cylinders mounted with manifold Capacity: 78,000 cubic feet Pressure @ 70oF: 250 PSIG

Acetylene Bulk Trailer

Acetylene

Size: Custom designed for each application, can consist of 2 or

more bays each 10 feet wide or include cylinder banks for

uninterrupted supply. Flash Arrestor: 10,000 - 20,000 scfh capacity Pressure Regulator: Controls pressure to 15 psig Flow Rate: 1,700 - 5,700 scfh after regulator

Trailer Docking Station

Acetylene

Off Loading StationOne Trailer Bay & Back-up Cylinders

Acetylene

Off Loading StationOne Trailer Bay & Back-up Cylinders