Liquid Argon Handling

1
Liquid Argon Handling

• FNAL Argon Experience
• Argon Deliveries
• Circulation Pumps
• Piping

2
FNAL Liquid Argon Experience

• E706, 140 tons
• DZero Test Beam, 40 tons
• Dzero Calorimeters, 100 tons
• Of these, Dzero has run twelve years

3
Common Features

• Oxygen 0.5 to 1 ppm
• No purification system
• Evacuated tanks
• Delivered by truck
• Trucks sampled upon arrival
• Storage tanks filled first
• Then transferred to detector cryostat.

4
Argon Delivery Process

• Truck vs. Railcar, cost driven
• Truck or car arrives with one ppm oxygen
• Fill one of several holding tanks
• Test oxygen, drift distance
• Pump to storage tank or purifier
• Analyze problems with chromatograph or
  spectrometer

5
Cryogenic Pumps

• Known technology
• Common on cryogenic trailers
• Used on several experiments, most recently
  pumping nitrogen at Dzero
• Used on Icarus

6
Pump Types

• For 1000 tons/day circulation
• 10 HP pump needed.
• Centrifugal pump
• May be internal or external to tank
• May be submerged motor or warm motor
• May have seals or magnetic drive

7
Pump Reliability

• Centrifugal pumps commonly run for years with
  little maintenance
• Dual pumps would be installed
• Automatic start, ability to evacuated and purge
  after repairs

8
Internal vs. External Pumps

• External pumps would be much easier to repair,
  then evacuate and purge.
• Internal pumps must have a submerged motor which
  could be a contamination risk
• Internal pumps more expensive since they require
  a large tube through the tank and a structure on
  the tank roof for lifting.
• Internal pump replacement would be a much bigger
  mechanical operation.
• The risk of drain pipe damage can be mitigated
  with internal valves, a careful design and
  maintenance of the tank bottom heaters.

9
Piping

• Most joints connections welded
• Metallic seals used wherever possible
• Non-metallic seal permeation
• Double seal and purge between seals
• May be vacuum or foam insulated