Despatch 926E Equipment Manual (C-155)Rev 2/11 - Manual (Page 19)

14
b. Shut off the valve at the cylinder.
c. Crack the hose fitting slightly, and allow the residual CO
2
pressure in the
hose to bleed off before disconnecting the hose.
d. Connect hose to new cylinder.
e. Open cylinder valve.
f. "Crack" the fitting at the bulkhead to bleed off gas and moisture.
g. Turn chamber on.
Installation of Liquid Nitrogen
Some models of test chambers use pressurized liquid nitrogen (LN
2
) so that lower test
temperatures may be reached. Line pressure should be between 55 kPa (8 PSI) and
310 kPa (45 PSI).

The following precautions should be observed in handling LN
2
:

Liquid nitrogen is extremely cold (-196

C or -320

F) at atmospheric pressure
and can damage skin or eyes on contact.

Insulated gloves and safety goggles or face plates should always be used in
handling LN
2
.

Clean cotton clothes or lab coats should be worn where LN
2
spillage or
prolonged contact with its vapors is a factor.

Smoking should be prohibited in the
immediate area were LN
2
is being
handled.

All handling equipment such as
funnels, dewars, piping and tubing
must be clean, dry and free of grease.

All transfer tubes, valves and other
equipment which reach liquid nitrogen
temperatures should be properly insulated with a non-absorbent insulation
which is properly contained within a vapor seal.

Liquid nitrogen is not in itself explosive or combustible; however, its low
temperature will cause condensation of the water vapor in the air and all the
WARNING: Nitrogen and carbon dioxide
gases can cause asphyxiation and death
if used in confined, poorly-ventilated
areas.
Nitrogen and carbon dioxide as liquid or
cold gases can cause freeze burns of
the eyes and skin.