Maintaining The Acetylene Supply - PerkinElmer aanalyst 200 User Manual

Maintenance

Maintaining the Acetylene Supply

Warning: Acetylene – Explosion Hazard
Acetylene can decompose explosively at pressures higher than
103 kPa / 1.03 bar / 15 psig.
WARNING
Always make sure that the acetylene outlet gauge pressure is below this value.
•
Depressurize both the fuel and oxidant gas hoses at the end of the working day or if you are
not going to use the instrument for an extended period. Close the cylinder valves to avoid the
possibility of gas hoses being subjected to the full cylinder pressure in the event that a
pressure regulator should fail.
•
Acetylene is supplied dissolved in a solvent such as acetone, and a small amount of solvent
carryover with the acetylene is normal. However, as tank pressure falls, the relative amount
of solvent entering the gas stream increases and can give erratic results, particularly for
elements such as calcium, tin, chromium, molybdenum and others whose sensitivity is highly
dependent on the fuel: oxidant ratio. The pressure drop is not linear with gas removal since
the acetylene is dissolved in a solvent, and a pressure of 600 kPa (6 bar; 85 psig) at ambient
temperature indicates that the cylinder is nearly empty. For this reason, replace acetylene
cylinders when the cylinder pressure drops to about 600 kPa (6 bar, 85 psig).
•
Always store and use acetylene cylinders vertically, rather than horizontally, to prevent
liquid acetone form reaching the cylinder valve.
•
The practice of 'cracking the valve' of an acetylene tank (that is, opening the valve slightly
for a very short period previous to attaching the regulator) is not recommended. While such
an action will clear the valve opening of dust or dirt particles and may remove acetone from
the cylinder valve, it is a potentially hazardous practice and one which should never be
attempted in the presence of an open flame, sparks or other possible sources of ignition.
9-50