GUIDELINES FOR HELIUM USAGE
User Certification: All users are requested to sign the certification sheet posted outside of B123 stating that they have read and understood these guidelines.
Availability: The liquefier operates approximately 2 days per week and produces more than enough helium to satisfy current demand. Therefore, in the absence of major equipment mal functions, it will be the responsibility of Cryoengineering (CE) to provide helium to all certified users.
Notification: Helium in the amount of 60L or less will be available within one workday of notification to CE. One calendar week of notification is required for cryostat cool downs needing 60L or more. MicroKelvin should give an additional one-week warning prior to a cool down. CE will, on a best effort basis, try to accommodate more urgent requests due to unforeseen problems. Requests for periodic amounts for ongoing experiments will be honored without repeated requests until users notify CE of changes in schedule or usage amounts. The preferred method of notification for NPB users is by sign-up sheets outside of B123 and for others (uK, UFBI, Chemistry, WM) by email. Notification by telephone or word of mouth is also acceptable. CE will acknowledge all requests.
Custom and Warm Dewars: Specific (custom) dewars will be filled and assigned to a specific user when requested but such requests should only be made if there is a real need. (CE has greater flexibility if all dewars are used in a common pool.) Warm dewars returned to CE do not get priority for refilling and may be unavailable for a period of at least one week.
Dewar Storage: Dewars in NPB, WM, CH and uK should be returned respectively to B123, WM130, CLB3O8 and the uK staging area as soon as possible after transfers. If it is necessary keep a dewar within a laboratory for multiple transfers, the user runs the risk of returning a warm dewar to CE.
Helium Recovery and Monitoring Practices: All users are encouraged to use procedures that minimize leaks. Specifically, close valves, plug in recovery and cryonet lines, fill out usage charts, measure and record helium levels before and after transfers, and return dewars to CE with all fittings attached.
Inter-Laboratory Horsetrading: Private trading of helium without CE's knowledge hinders the ability of CE to respond to changing demand and allocate helium in an efficient manner. There are rare cases, however, when an unexpected need arises, and CE cannot be notified in a timely manner. In such instances, the user in need of helium (user B) can solicit helium from another user who has been allocated helium (user A). For all such transactions, the total amount used by A and B should not exceed the amount originally reserved for A. This transaction should be reported to CE as soon as practicable and notification made for additional needs (if any).
Priorities: If helium is in short supply, then highest priority will initially go to users who have cold cryostats. If shortages persist, priorities will be decided by the TOC.
Feedback: The TOC and CE welcome all constructive comments and suggestions concerning these guidelines.
Technical Operations Committee (TOC):
Cryogenic Services (CE):