Taylor-Wharton Liquid Withdrawal Device User Manual

TW-43

LIQUID
WITHDRAWAL DEVICE

The Liquid Withdrawal Device (L WD) provides convenient
pressure transfer to liquid nitrogen from LD25,LD35, and
50LD Dewars. The device clamps directly to the special
neck flange that is found under the plastic trim collar
around the neck of these containers.

Flow rates up to 8 liters per minutes are possible at
operating pressures up to 10 psig (0.7 bar/69 kPa). Liquid
can be dispensed directly from the L WD via the spout
provided, or through a standard cryogenic hose connected
to the liquid outlet.

Filling a Dewar is accomplished by pressure transfer
through the withdrawal device. (See Filling Instruc­tions.) This filling method allows replenishment of the

liquid supply in the Dewar without removing the L WD,
while keeping the liquid saturated at a pressure sufficient
to sustain liquid withdrawal.

For Liquid Nitrogen
LD25, LD35, and
50LD Dewars

Safety

Before using this equipment, read these instructions
carefully. Also, read and understand the instructions sup-

plied with your Dewar and the Handle with Care booklet
packed with all Liquid Nitrogen Dewars. The Handle with
Care booklet (Form TW-10) gives detailed information on
the safe handling of liquid nitrogen. Additional copies of
these publications can be obtained from your supplier. Do
not modify LWD or Dewar or use in a manner other than that
described in accompanying instructions and documentation.

Contact with liquid nitrogen or cold gas may cause
serious freezing (frostbite) injury . Do not touch liquid or

cold metal surfaces with your bare skin. Always wear a face
shield and gloves when transferring liquid nitrogen.

Nitrogen gas can cause suffocation without warning.

In a confined area, nitrogen gas from this equipment may
displace air required for breathing. Store and use this
equipment only in well-ventilated areas.

Use only containers designed for low-temperature
liquids. Cryogenic containers should be filled SLOWLY to

minimize stresses which can damage the container .

Vent all pressure from a Dewar before attempting to
remove the Liquid Withdrawal Device. If the band clamp

securing the L WD to a dewar is loosened while there is
pressure in the Dewar, cold gas or liquid could be expelled
causing personal injury .

Liquid Withdrawal Device is for use with liquid nitrogen
only . LWD is for use on specific model Taylor-Wharton

Dewars listed above.

Pressure in Dewar with LWD installed should never
exceed 10 psi. Fill dewar from supply source at 22 psi or

less. Do not pressurize using compressed air.

Installation

1. Remove the necktube cap/core from the Dewar.

2. Remove 3 flat-head mounting screws in the base of
the plastic trim collar around the neck of the Dewar,
remove the collar and discard or save for later. It is not
used while the LWD is installed.

3. The liquid withdrawal tube (the longer of the two plastic
tubes) is scored approximately 6 in. (152 mm) from the
end. This tube must be shortened for use with a LD25
or LD35 Dewar by breaking off the 6 in. (152 mm)
section. Discard the 6 in. (152 mm) piece. The tube is
used as supplied with the LD50.

valve. Tighten the compression nut s with a wrench to
secure.

5. Position the safety cable assembly around the top of the
Dewar, underneath the flange. Loosen V-Band Clamp
until the clamp is large enough to remove from the
L WD. Drop the band clamp around the flange on the
Dewar (see Figure 2).

6. Clean the flange O-ring and apply a thin layer of silicone
grease before placing it on the grooved flange.

NOTE: Be sure flanges surfaces are warm, clean and
dry . The O-ring must be cleaned and lightly lubricated
before installing the LWD.

7. Carefully lower the LWD unit into the Dewar. The LWD
should rest firmly centered on the neck flange of the
Dewar; the liquid withdrawal tube should not touch the
bottom of the Dewar.

8. Place the band clamp around the flanges of both the
L WD unit and the Dewar. Be sure that the clamp is
properly engaged on both flanges. Tighten the clamp –
hand tighten only .

9. Attach the snap of the safety cable to the ring on the
LWD (see figure 2).

4. Insert the longer plastic tube into the underside of the
flange assembly , beneath the LIQUID valve. Insert the
shorter plastic tube into the threaded fitting on the
underside of the flange assembly , beneath the VENT

10. If the spout assembly is to be used, install it on the
outlet fitting above the LIQUID valve. The phase separa­tor will ensure a controlled flow of liquid.