PerkinElmer AAnalyst 700, User Manual

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Laboratory Requirements
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Acetylene supply
The acetylene supply should be of ‘atomic absorption’ grade.
Grade: Suitable acetylene typically has a minimum purity specification of 99.6%
with the actual assay being about 99.8%. Acetylene is supplied dissolved in
acetone to prevent explosive decomposition. You should not use acetylene that is
dissolved in any other solvent. Experience indicates that solvents can be carried
through the regulator with the acetylene and can weaken, to the point of rupture,
the walls of the tubing carrying the acetylene to the burner, causing a potential
hazard.
Cylinder Specifications: A size 1A acetylene cylinder contains about 8500 liters
(300 cubic feet) of acetylene and usually lasts about 30 hours of burning time with
an air-acetylene flame. With a nitrous oxide-acetylene flame, the same size
cylinder will last about 10 hours.
Flash Arrestor: PerkinElmer recommends the use of the Flash Arrestor (P/N
N930-0068). The flash arrestor provides a positive shutoff of gas by checking the
reverse flow under all conditions. It also stops the gas supply when a flashback
occurs. The flash arrestor can be directly connected to the acetylene fuel line.
Piping/Tubing/Fittings: Use galvanized iron, steel, or wrought iron tubing. Never
use copper tubing with acetylene. Joints may be welded or made up of threaded
or flanged fittings, typically stainless steel or aluminum, or brass composed of
less than 65% copper. Rolled, forged, or cast steel or malleable iron fittings may
also be used. Cast iron fittings cannot be used safely for acetylene lines.
Warning: Acetylene – Explosion Hazard
Acetylene can decompose explosively at pressures higher than 103 kPa/
1.03 bar/15 psig.
• Always make sure that the acetylene outlet gauge pressure is below this
value.
Warning: Risk of explosion
Acetylene can react with copper to form a readily explosive compound.
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Never use copper tubing or fittings for acetylene gas lines.