Taylor-Wharton EF-1000 - Manual (Page 21)

BT-472 Rev. B
21
1.
Leak test joints between the high pressure cylinder regulator and the dump valve. Joints must be leak free
before proceeding.
2.
Close the on/off valve. Open the dump valve.
3.
Open the high pressure cylinder valve.
4.
Set the high pressure regulator above the desired set point for the economizer.
5.
Slowly open the on/off valve for a few seconds and then close it.
6.
When the regulator under adjustment closes, the economizer set point is indicated on the upstream pressure
gauge.
7.
To reset the regulator, loosen the lock nut on the adjusting screw. Raise the setpoint by turning the
adjusting screw clockwise; lower the setpoint by turning the screw counterclockwise. After adjustment,
repeat steps 5 and 6 to check the setting before reinstalling the regulator on the liquid container.
8.
The economizer regulator should be reinstalled oriented horizontally with the tube compression fitting
threaded into the side port.
Instruments
User adjustment of the pressure gauge or liquid level gauge is not possible. If the gauges are malfunctioning, they must
be replaced. Empty the container of liquid and completely depressurize it before replacing either gauge.
Note that the liquid level gauge may read erratically while the safety valve is venting. This is normal and will stop when
the safety valve reseats.
Checking Vacuum
Cryogenic containers are two containers, one within the other. The space between the containers acts as a highly
efficient thermal barrier including high technology insulation, a vacuum, and a vacuum maintenance system. Each
serves a very important part in the useful life of the container. The high technology insulation is very effective in
preventing radiated heat from entering the inner container. Unfortunately, the perfect vacuum cannot be achieved since
trace gas molecules begin to enter the vacuum space from the moment of manufacture. The vacuum maintenance system
consists of materials that gather trace gas molecules from the vacuum space. The maintenance system can perform its
function for years, but however it has a limited capacity. When the vacuum maintenance system becomes saturated it
can no longer maintain the vacuum integrity of the container. The change will be very gradual and may go unnoticed for
several years. When the vacuum in the insulation space is no longer effective, the following symptoms may appear:
1.
With liquid in the container, the outer casing will be much colder than comparative containers.
2.
Frost, indicating the liquid level, may be visible on the outer casing of the container.
3.
Condensation may form on the container. Note that some icing or condensation is normal around the piping
connections of the vessel. Condensation may also occur on the vessel outer surface as a result of high
humidity.
4.
The relief valve will open continuously until the container is empty.
If a loss of vacuum integrity is suspected, the container’s normal evaporation rate (NER) should be checked. The test
procedure explained below measures the actual product lost over time.
1.
Fill the container with approximately 400 pounds of liquid nitrogen.