This procedure is used to obtain test specimens for those propellants that occur as gases at about 25and that are stored in pressurized cylinders.Use a stainless steel sample cylinder equipped with a stainless steel valve and having a capacity of not less than 200mLand a pressure rating of 240psi or more.Dry the cylinder with the valve open at 110for 2hours,and evacuate the hot cylinder to less than 1mm of mercury.Close the valve,cool,and weigh.Connect one end of a charging line tightly to the propellant container and the other end loosely to the sample cylinder.Carefully open the propellant container,and allow the propellant to flush out the charging line through the loose connection.Avoid excessive flushing,which causes moisture to freeze in the charging line and connections.Tighten the fitting on the sample cylinder,and open the sample cylinder valve,allowing the propellant to flow into the evacuated cylinder.Continue sampling until the desired amount of specimen is obtained,then close the propellant container valve,and finally close the sample cylinder valve.[Caution—Do not overload the sample cylinder;hydraulic expansion due to temperature change can cause overloaded cylinders to explode. ]Again weigh the charged sample cylinder,and calculate the weight of the specimen.

Transfer a 100-mLspecimen to a tared,pear-shaped,100-mLcentrifuge tube containing a few boiling stones,and weigh.Suspend a thermometer in the liquid,and place the tube in a medium maintained at a temperature of 32above the expected boiling temperature.When the thermometer reading becomes constant,record as the boiling temperature the thermometer reading after at least 5%of the specimen has distilled.Retain the remainder of the specimen for the determination of High-Boiling Residues.

Allow 85mLof the specimen to distil as directed in the test for Approximate Boiling Temperature,and transfer the centrifuge tube containing the remaining 15mLof specimen to a medium maintained at a temperature 10above the boiling temperature.After 30minutes,remove the tube from the water bath,blot dry,and weigh.Calculate the weight of the residue.

Prepare a cooling coil from copper tubing (about 6mm outside diameter ×about 6.1m long)to fit into a vacuum-jacketed flask.Immerse the cooling coil in a mixture of dry ice and acetone in a vacuum-jacketed flask,and connect one end of the tubing to the propellant sample cylinder.Carefully open the sample cylinder valve,flush the cooling coil with about 50mLof the propellant,and discard this portion of liquefied propellant.Continue delivering liquefied propellant from the cooling coil,and collect it in a previously chilled 1000-mLsedimentation cone until the cone is filled to the 1000-mLmark.Allow the propellant to evaporate,using a warm water bath maintained at about 40to reduce evaporating time.When all of the liquid has evaporated,rinse the sedimentation cone with two 50-mLportions of pentane,and combine the rinsings in a tared 150-mLevaporating dish.Transfer 100mLof the pentane solvent to a second tared 150-mLevaporating dish,place both evaporating dishes on a water bath,evaporate to dryness,and heat the dishes in an oven at 100for 60minutes.Cool the dishes in a desiccator,and weigh.Repeat the heating for 15-minute periods until successive weighings are within 0.1mg,and calculate the weight of the residue obtained from the propellant as the difference between the weights of the residues in the two evaporating dishes.

Proceed as directed under Water Determination á921ñ,with the following modifications:(a)Provide the closed-system titrating vessel with an opening through which passes a coarse-porosity gas dispersion tube connected to a sampling cylinder.(b)Dilute the Reagentwith anhydrous methanol to give a water equivalence factor of between 0.2and 1.0mg per mL;age this diluted solution for not less than 16hours before standardization.(c)Obtain a 100-g specimen as directed under General Sampling Procedure,and introduce the specimen into the titration vessel through the gas dispersion tube at a rate of about 100mLof gas per minute;if necessary,heat the sample cylinder gently to maintain this flow rate.

For those aerosols that use propellants,perform the tests specified in the individual NFpropellant monographs.