The North endcap calorimeter vessel was recieved on July 1, 1990. A cooldown of the pressure vessel with liquid nitrogen was performed on July 10-11 to check the vessel's integrity. With the pressure vessel cold, the insulating vacuum was monitored for leaks. Through out the testing, the insulating vacuum remained good and the vessel passed the test. The cold test was carried out per the procedures of D-Zero engineering note 3740.220-EN-250. The test was very similar to the cold test performed on the Central Calorimeter in October of 1987. Reference D-Zero engineering notes 3740.210-EN-122, 3740.000-EN107, and 3740.210-EN-110 for information about …
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Fermi National Accelerator Laboratory (FNAL), Batavia, IL
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The North endcap calorimeter vessel was recieved on July 1, 1990. A cooldown of the pressure vessel with liquid nitrogen was performed on July 10-11 to check the vessel's integrity. With the pressure vessel cold, the insulating vacuum was monitored for leaks. Through out the testing, the insulating vacuum remained good and the vessel passed the test. The cold test was carried out per the procedures of D-Zero engineering note 3740.220-EN-250. The test was very similar to the cold test performed on the Central Calorimeter in October of 1987. Reference D-Zero engineering notes 3740.210-EN-122, 3740.000-EN107, and 3740.210-EN-110 for information about the CC cold test. The insulating vacuum space was pumped on while equipment was being connected to the pressure vessel. Two hours after starting to pump with the blower the vacuum space pressure was at about 210 microns. Pumping on the vacuum space for the next 15 hours showed no progress and a leak detector was connected to the pumping line. A leak check showed a leak in a thermocouple feedthru on the vacuum space relief plate. After fixing the leak, the pressure dropped to 16 microns in less than one hour. A rate of rise test was performed starting at a pressure of 13 microns. The pressure rose to 39 microns within 8 minutes and then only rose to 43 microns in 2.5 hours (1.6 microns/hour). After all connections were made to the pressure vessel, a vacuum pump with an estimated effective pumping speed of about 70 scfm was valved on. The lowest pressure achieved after 2 days of pumping was 80 microns. Valving out the pump for 30 minutes resulted in a 5 micron per minute rate of rise. The rate of rise was considered acceptable since there were known leak paths through the bolts of the signal ports. The EC North vessel was rolled outside of Lab A in preparation for a 5000 gallon liquid nitrogen trailer which arrived July, 10 at 8:00am. Before filling the vessel, the vacuum space pump was valved off. The pressure in the vacuum space was 12 microns at that point. During the next 24 hours of the test, the vacuum space pressure decreased to 5 microns. A plot of the vacuum space pressure with time is included at the end of this note. The liquid nitrogen was pressure transferred from the trailer at 29 psig to the pressure vessel at 1 psig for ten hours. At that time there was sufficient (16-inch) of liquid nitrogen in the vessel to turn the LN2 trailer delivery pump on. Thirteen and one half hours after starting the fill, the vessel had 50-inch of LN2 collected. During the latter part of the filling, about twelve loud metallic bangs were heard. The noises came at random intervals with sometimes five minutes between and other times an hour between. The best way to describe the sound is to imagine the sound made if someone was trapped inside the vessel with a baseball bat and took a good swing. The trailer was disconnected and the the vessel was left overnight for ten hours. Due to the slow LN2 fill rate, the temperature gradient in the pressure vessel shell was not very large, only about 25 kelvin difference was found from a RTD in the warm-up nozzle of the vessel and the resistors of the liquid level probe. A temperature versus time graph is included at the end of this note.
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