CHART Cryo-Cyl80HP, Product Manual

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12
Introduction Product Manual - Liquid Cylinders
Principle of Operation
The various Dura-Cyl
®
/Cryo-Cyl
®
Liquid Cylinders have the
same general operating characteristics. Each model of liquid
cylinder has the ability to be filled with a cryogenic product,
build pressure inside the vessel, and deliver either liquid or
gas for a specific application.
The following section will discuss the theory behind these
operations. Later sections of this manual will give step-by-
step procedures for the operation on each of the specific
models of liquid cylinders
Liquid cylinder operation is done completely with the control
valves located on the top of the tank. The valves are labeled
and color coded for easy identification: Fill/Liquid Valve -
blue; Gas Use Valve - green; Vent Valve - silver; Pressure
Building Valve - Green
Filling Procedures
The following recommendations should be used to optimize
liquid cylinder filling:
• Keep the transfer lines as short as possible. Long
uninsulated transfer lines will result in higher fill losses
and longer fill times.
• Any time liquid can be entrapped in a line between two
valves, the line must be equipped with a safety relief
device
• Conduct the filling operation in as short a time as
possible.
• Do not over fill. Fill only to the weight allowable by the
specification.
• Use a minimum number of bends, valves and reducers.
• Use the largest transfer line possible - at least 1/2" ID.
The liquid cylinder should be visually inspected before
every fill for possible damage, cleanliness and suitability for
its intended gas service. If damage is detected (e.g. serious
dents, loose fittings, etc.) remove it from service and repair
the unit as soon as possible.
All Chart liquid cylinders are tested for performance with
low-purity liquid nitrogen. For this reason liquid cylinders
intended for use in another service should be thoroughly
purged with the applicable gas prior to filling.
When filling a liquid cylinder with a cryogenic liquid, the
transfer may be made with a centrifugal pump or through a
pressure transfer operation.
Pressure Transfer
Liquid will always flow from a vessel of higher pressure to
one with low pressure. This method is commonly used to
fill liquid cylinders by connecting a transfer line between
the delivery source and the Fill/Liquid valve of the liquid
cylinder. The transfer takes place as the vent valve of the
liquid cylinder is opened. This allows gas to escape and
lowers the pressure in the liquid cylinder. This method
should always be used for liquid only vessels. Figure 10
shows the pressure transfer method of filling.
Figure 10
Pump Transfer
The pump transfer method lowers the product losses
associated with filling. Liquid may be pumped into the
cylinder so that venting is not necessary The vent valve
on the liquid cylinder has a spray header that will splash
the incoming cold liquid onto the somewhat warmer gas in
the tank. The cold liquid will actually collapse the vessel
pressure while being sprayed into the warmer gas. This
method of filling works well with vessels that are used
regularly and do not warm up between fills. Figure 11 shows
the pump transfer method.