Proposal for the Use of Liquid Nitrogen in Random Hall's Liquid
Nitrogen Ice Cream Events
Yongquan Lu ()
Feb 25,2013
1) Scale of Events
Over the course of CPW (April 11th - 14th, 2013), Random Hall plans to prepare approximately 300 servings of liquid nitrogen ice cream. The preparation and distribution of the ice cream will take place in Random Hall's main lounge and will be structured in a manner similar to the liquid nitrogen ice cream events of previous years. There will be at most 2 flavors of ice cream made at a time (about a gallon each) during an event, and each flavor will be made by at least 2 people trained to handle liquid nitrogen.
2) Setup
All equipment is only used for food preparation and is not borrowed from a lab.
The unfrozen ice cream will be prepared and stored in our basement refrigerators prior to the event and will be brought into the main lounge as the event starts to be mixed with liquid nitrogen. Several two-person teams will prepare these ingredients, handle and mix liquid nitrogen with the ice cream mixture, and serve the frozen ice cream. The scale of this event is such that a large group is unnecessary. Syrups will also be frozen by two-person teams in bowls of liquid nitrogen.
3) Handling and Safety of Liquid Nitrogen
Prior to the beginning of CPW, the Dewars of liquid nitrogen will be delivered to the back entrance of Random Hall. The Dewars will be rolled down a pre-existing wooden ramp into the Random Hall basement and from there into the 290-side (north side) air shaft. The doors to the shaft are alarmed and monitored during daylight hours by desk staff and during night hours by the campus police, allowing safe and secure storage of the Dewars and limiting access to authorized students. The Dewars in the shaft will be placed in such a way as to avoid the obstruction of the emergency exit.
Dispensing of liquid nitrogen will take place in the shaft with a pre-inspected cryogenic corrugated hose. The liquid nitrogen will be dispensed into a 50 liter narrow-necked Dewar. This 50 liter Dewar will be used to transport the liquid nitrogen from the large Dewar to the Random Hall main lounge, carried up the front stairs, which are straight, rather than up the twisting back stairs to avoid splashing. As it is heavy when filled, two people will carry it with a third clearing the way for the Dewar. To further avoid splashing, the Dewar will be kept at most three-fourths full. The 50 liter Dewar will be used to dispense liquid nitrogen into two 1 gallon Dewars, which can easily be handled by a single person. The dewars will be capped at all times except when they are filled or emptied to reduce exposure to the air and ice buildup. The smaller 1 gallonDewars will be used to pour the liquid nitrogen into the bowls for mixing liquid nitrogen ice cream.
Any person who volunteers to deal with liquid nitrogen before the event will be given a lecture and demonstration on the safe handling of liquid nitrogen by a person who has had one or more years of experience. During the dispensing of liquid nitrogen and during ice cream making events, the volunteers will wear cryogenic gloves which have been inspected beforehand for signs of damage, long sleeved shirts, long pants, close-toed shoes, and safety goggles. All preparation of ice cream will be done on tables which have been inspected beforehand for stability in Random Hall's main lounge. The main lounge is large and well-ventilated, with direct window access to the shaft. During mixing, workers will be properly spaced to avoid accidentally jostling those handling liquid nitrogen. While one member of each team is handling the liquid nitrogen, the other will be on hand during mixing to quickly clean any spills. Any onlookers will be kept at least 3 feet away from the mixing tables.
After the last liquid nitrogen ice cream event is completed, all dispensing equipment will be removed.Any remaining liquid nitrogen in the Dewar will be used for demonstrations and training next year's staff. Staff will be aware of the hazard associated with ice buildup over time and avoid such occurrences by ensuring that the total length of time the 50L Dewar is actually storing LN2 is less than a week. The DEP regulations prohibit releasing 10lbs or more of LN2 so the staff will not empty the large dewar before moving it to the pickup location as specified by Airgas.Staff may, however, pour out the small amount that is left in the 50L and 1 gallon dewars at the end of the demo or training, since this would be well below the 10lb RQ. The large Dewar will then be moved to the pickup location as specified by Airgas.
4) Food Safety
All members of teams will work according to the MIT Campus Diningfood safety guidelines, handling the ice cream ingredients only after properly sterilizing their hands and tying any long hair back. Those serving the ice cream after it has been prepared will use latex gloves. As perishable heavy cream will be used in the preparation of the ice cream, we will insure that it is kept refrigerated so as to remain safe for consumption. No eggs, raw or otherwise will be used in the preparation of this ice cream. A complete list of all ingredients in the ice cream will be posted at all locations where it is served.