Compressed Gases are stored in various locations through the CHESS facility. Always consult with the CHESS Operator or other qualified personnel if your work requires compressed gases, or for modification of hookups in your work area.
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Do not tamper with any safety device on a cylinder, and do not modify or lubricate any cylinder valve.
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Do not attempt to move a compressed gas cylinder without notifying the CHESS Operator.
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Compressed gas cylinders must be securely anchored to walls to prevent tipping over.
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If you suspect a cylinder is leaking and may contain a toxic, corrosive or poisonous gas, evacuate the area and summon the CHESS Operator immediately.
Cryogens:
Liquid nitrogen (LN2) is available at CHESS. Liquid helium can be supplied if arrangements are made in advance of your visit.
The main risks associated with cryogens are burns as a result of contact with skin or eyes, and asphyxiation. Wear gloves and glasses while handling LN2. Make sure the area you are working in is well ventilated. Be particularly alert in the event of a spill.
Five liter dewars are available for LN2 transport; the procedure for filling these will be covered in the MacCHESS orientation. Non MacCHESS users should ask the CHESS Operator for instruction in using the LN2 supply system. All LN2 must be signed out on the clipboard at the LN2 supply area.
Users of the crystallography beam lines (A1, F1, F2) who have frozen samples have a 50 liter dewar of LN2 inside the hutch supplying a coldstream. A full dewar lasts for approximately three days. Users are responsible for checking the level of LN2 in the dewar. At A1 station the LN2 level is accomplished by using a dip stick; when the level of LN2 drops to 5 inches it is time to fill the dewar. F1 and F2 have auto fill systems and users of the stations need only monitor the LN2 level once a day. A1 users fill the dewar in the hutch using a wheeled 80 liter transport dewar. Procedures for filling the transport dewar and then the supply dewar in A1 hutch are covered in the MacCHESS orientation. The CHESS Operator can answer questions about manual filling and automatic filling and also provide assistance as required.
