Mullins Lab Standard Operating Procedure

 

 

Cryogenic Liquids

 

Safety:

 

Note:   Never touch the outside of a Dewar with bare hands, as the DewarÕs wall temperature can be much colder (as in sub-zero) than the ambient room temperature.  Prolonged contact could lead to frostbite.

 

Note:   Never use a Dewar that does not have a regulator on it.

 

Dress Code:

 

1.              Always wear heavy-duty temperature resistant gloves such as Low-Temp gloves from Lab Safety Supply and goggles when working with liquefied gases.

 

2.              use the same general precautions you would take when working with extremely cold or extremely hot objects.  DO not expose to bare hands.  Do not wear open toed shoes.  Wear a lab coat.

 

3.              Keep exit port pointed away from you and other people when pouring cryogenic liquids.

 

Operation/usage:

 

1.              Make sure the gas is appropriate for the regulator it is flowing though.  Never release toxic, flammable, or corrosive gases in lab.

 

2.              Do not use liquid oxygen in front of a flame.  Liquid oxygen rapidly boils at room temperature into gaseous oxygen, promoting a real fire hazard.  Liquid oxygen may also ignite or detonate materials on contact.

 

3.              Test the regulator for leaks.  DO NOT USE A LEAKING REGULATOR.

 

4.              Attach the regulator to the cylinder/Dewar.

 

5.              For most regulators, turn the pressure-adjusting knob counterclockwise until it completely stops or it turns freely. This depressurizes the system.

 

6.              STAND TO ONE SIDE and open the cylinder/Dewar valve.

 

7.              Turn regulator pressure adjusting knob clockwise until desired pressure is reached. You can also set a flow meter control to the desired rate.

 

 

 

Shutdown:

 

1.     Close cylinder/Dewar valve

 

2.     CAREFULLY vent system to zero psig (or room atmospheric pressure).

 

3.     If the regulator is equipped with a flow meter, close the control valve after the system is vented. On regulators without flow meters, turn regulator pressure knob counterclockwise to a complete stop or until the knob can freely turn.

 

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