Test Results
October 31, 2003
The Test: cleaning, cold cycling, and leak checking of two parts of the LH2 plumbing
internal to the NPDG vacuum vessel; cleaning and leak checking of two H2
plumbing parts external to the vacuum vessel.
Purpose:
to verify that these four welded, CF-flanged components of the LH2 target are
leak tight
The Parts: 1) a tube with a 90o bend, a bellows, and a ¼-inch VCR side connection; 2) a
short tube with a 90o bend (to be used in the external plumbing between a side
connection of the 2.75”-CF cross in the vent line and a rupture disk); 3) a
welded, S-shaped tube; 4) a transition piece between .75”-CF flanged and
4.5”-CF flanged components n the H2 vent line
On this date, parts 1-4 were found to be He leak tight at rate of ≤1x10-9 cc/s. The
procedure followed was first to verify that parts 1-4 were leak tight at room temperature.
Then, all were cleaned by submersion (2.5 minutes) in a solution of 25 % HNO3 + 2 %
HF + 73 % water, by volume. Another leak check followed a through rinse in hot tap
water, a final rinse in de-ionized water, a wipe down to remove the passivating layer, and
drying.
Parts 1-3 (seen L to R in the photos below) were then joined (with copper CF gaskets)
and continuously connected to the leak checker during two cycles between room
temperature and equilibrium in LN2. At each end of the temperature range, liberal
spraying with He failed to find a leak anywhere. At the end of the tests, a final check
determined that the sensitivity of the leak checker had remained in calibration.
Tests Performed By: Bill Lozowski and Alan Eads