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Safety precautions for liquid nitrogen, Extreme cold - cover eyes and exposed skin, Keep equipment area well ventilated – Taylor-Wharton KRYOS Controller User Manual

Page 5: Liquid nitrogen system, Electrical

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KRYOS

SAFETY PRECAUTIONS FOR LIQUID

NITROGEN

Nitrogen is an inert, colorless, odorless, and tasteless gas making up four-fifths of
the air you breathe – and can be

very dangerous. Air is roughly one-fifth oxygen.

Liquid nitrogen is at a temperature of -196°C (-320°F) under normal atmospheric
pressure.

Extreme Cold - Cover Eyes and Exposed Skin

Accidental contact of liquid nitrogen or cold issuing gas with the skin or eyes may
cause a freezing injury similar to frostbite. Handle the liquid so that it won’t splash
or spill. Protect your eyes and cover the skin where the possibility of contact with the
liquid, cold pipes and cold equipment, or cold gas exists. Safety goggles or a face
shield should be worn when operating this equipment. Insulated gloves that can be
easily removed and long sleeves are recommended for arm protection. Trousers
without cuffs should be worn outside boots or over the shoes to shed spilled liquid.

Keep Equipment Area Well Ventilated

Although nitrogen is non-toxic and non-flammable, it can cause asphyxiation in
a confined area without adequate ventilation. Any atmosphere not containing
enough oxygen for breathing can cause dizziness, unconsciousness, or even death.
Nitrogen, a colorless, odorless, and tasteless gas, that cannot be detected by the
human senses and will be inhaled normally as if it were air. Without adequate
ventilation, the expanding nitrogen will displace the normal air resulting in death.

Liquid Nitrogen System

The liquid nitrogen supply pressure at the inlet to the refrigerator should be in
the range of 10 psig (0.7 bar/69 kPa) to 20 psig (1.4 bar/138 kPa) for optimum
performance. Higher operating pressures will increase transfer losses and create
excessive turbulence of the liquid in the refrigerator which can generate false signals
to the liquid level controller causing the refrigerator to under-fill. In “liquid phase”
storage applications, excessive turbulence can cause splashing which could result in
personal injury and/or damage to the refrigerator. When installing piping or fill hose
assemblies, make certain a suitable safety relief valve is installed in each section of
plumbing between shut-off and solenoid valves. Trapped liquefied gas will expand
greatly as it warms and may burst hoses or piping causing damage or personal
injury. A relief valve is installed in the refrigerator plumbing to protect the line
between the customer supplied shut-off valve and the refrigerator solenoid valve.

Electrical

The liquid level controllers used with these refrigerators operate from 24/16.5 VAC.
However, the external transformer does have a 110/220 VAC primary. Disconnect
the electrical power cord from the outlet before attempting any service.

For more detailed information concerning safety precautions and safe practices
to be observed when handling cryogenic liquids consult CGA pamphlet P-12
“Handling Cryogenic Liquids” available from the Compressed Gas Association,
1235 Jefferson Davis Highway, Arlington, VA 22202.

WARNING:

The following safety

precautions are for

your protection.

Before installing,

operating, or

maintaining this unit

read and follow all

safety precautions

in this section

and in reference

publications. Failure

to observe all safety

precautions can

result in property

damage, personal

injury, or possibly

death.

Caution:

When installing field

fabricated piping,

make certain a

suitable safety relief

valve is installed

in each section of

piping between

shut-off and solenoid

valves.

WARNING:

Inlet pressure should

not exceed 22 psig

(1.5 bar/152 kPa).

Higher pressures

could result

in damage to

equipment.

WARNING:

Electrical shock can

kill. Do not attempt

any service on these

units without first

disconnecting the

electrical power cord.