Standard Operating Procedure (SOP) for Tousimis Supercritical Dryer
Contents
1. HEAT cycle for another 2 4 minutes recording the T and P values on the log sheet Typical heat cycle time is 10 minutes Then proceed to the bleed cycle by pressing the BLEED button Record T and P on the log sheet in 1 minute intervals The chamber temperature will automatically be kept above the critical temperature Tc 31 3 C The chamber pressure will gradually drop at a rate of around 100 psi minute Once the chamber pressure is below 400 psi press the VENT button The chamber should reach atmospheric pressure in 3 5 minutes Once atmosheric pressure has been reached open the chamber and remove your sample Close the chamber immediately to prevent moisture from building up in the chamber Record the final CO tank weight on the log sheet Compute the CO used in this run and enter in the log sheet Compute the total CO2 used for this tank add the current CO to the previous tank total This should be less than 25 lbs Compute the total CO2 used for this filter add the current CO2 used to the previous filter total This should be less than 500 Ibs Enter any comments on the log sheet Close the CO gt tank and leave the Samdri 795 in VENT mode for a few minutes to exhaust any remaining CO in the system Turn off Samdri 795 and wipe the exhaust hoses Roll up exhaust hoses and store2. Standard Operating Procedure SOP for Tousimis Supercritical Dryer Model Samdri 795 User Name Date Start Time Cool Time 60 90 sec Stop Time Purge Time 10 min CO weight Ibs CO used this run 2 0 Ibs Total CO this tank lt 25 Ibs UL Total CO this filter lt 500 Ibs TES T amp S Heat Cycle Bleed Cycle tmn TEC Pes tmin TEC Pips a Jooo o ee eae as ee Pt OT a ee o y a ooo o y o 2 TC ae al a a ooo o y y Ooa TT ooa ooo o y ee ee y ee ee y fe O e eee eee OOo zo o ooo o y OOo zo o ee y O o 8 Jo o o y y a Jo o o y y Oo o a J y O o a y oo owo oo o y oowoo ooo o y Oooo ooo o y a ooo o y ae ooo o y a ooo o Ooa ooo o y Oo oas ooo o y ooa ooo o ooa ooo o y Ooo oas ooo o Ooo oas ooo o ooe Jo ooo o 76 ee o y Oooo o ooo o y oas y ee ooo ee a ooo o ooa ooo o mT o y 2 o o y Comments Signature Form Last modified March 19 2003 Tousimis Samdri 795 supercritical dryer User log sheet NOTE This is the short SOP The detailed SOP is found the Samdri 795 User Manual S N 8915 All users should read the user manual prior to operating the Samdri 795 1 Turn on Samdri 795 by flipping the power switch on the right side panel The vent light should illuminate Leave the Samdri 795 on for at least five minutes before processing 2 Fill out name date starting time and run on the log sheet 3 Make sure the white COOL and cle
3. ar PURGE VENT BLEED hoses are leading to the dirty fume hood Also make sure the PURGE VENT BLEED hose exhausts into a beaker to catch any purged liquids 4 Set the purge timer to 2 or 1 5 1 75 etc as necessary This sets the purge time in five minute increments A purge time of 10 minutes 2 setting on purge timer is usually sufficient NOTE The user should not have to adjust any settings The Samdri 795 has been adjusted to operate properly with minimal adjustments Notify super user if Samdri 795 does not operate properly Make sure the CO tank is at room temperature Open CO tank valve Measure weight in Ibs and record total in the start weight section of the log sheet Make sure that there is at least 25 lbs of CO available i e for a standard 50 lb tank make sure that at most 25 lbs of CO2 have been used a The tank should be on the scale and the digital read out for the scale should be on If it is not remove the tank from the scale and press and hold on and lb kg for several seconds b The read out should display 4400 then A oF and finally 0 0 The scale is now zeroed and ready for use c Place the CO tank back on to the scale Open the Samdri 795 chamber Fill the chamber with ultra pure methanol or ethanol or IPA and place sample in chamber making sure it 1s always covered with alcohol The chamber should have sufficient alcohol in it to completely cov
4. er the sample Close the chamber and tighten the three nuts uniformly by hand Never use a wrench to tighten the nuts Press the COOL button The Samdri 795 will cool the chamber to 0 C 5 C and will automatically stop Record the cool time on the log sheet A typical cool time is 60 90 seconds Next press the FILL button The Samdri 795 will now fill with liquid CO2 During fill the chamber temperature is automatically maintained at T lt 10 C After two minutes the fill automatically stops The Samdri 795 now automatically advances to the PURGE mode methanol or other ultra pure alcohol is forced out of the chamber and is replaced completely by liquid CO2 Monitor the chamber temperature check that the chamber temperature remains in the range 5 C lt T lt 10 C This ensures that the CO remains in the liquid state Note that the Samdri 795 will perform cooling automatically during the PURGE mode During purge you will notice a For the first few minutes the exhaust from the clear PURGE VENT BLEED hose will be clear liquid or slurry 1 e alcohol Make sure it is exhausted into a beaker or other proper container under the dirty fume hood The exhaust should be pure methanol no contaminants b After all the alcohol has been purged from the chamber only CO will be exhausted Because the CO encounters a low pressure environment atmosphere as it leaves the high pressure chamber it will cool and be e
5. xhausted as clear white flakes This is normal You can check to see if there is any alcohol in the exhaust by holding a cleanroom wipe at the end of the PURGE VENT BLEED hose Solid CO will not leave a wet spot on the cleanroom wipe but alcohol will 10 11 12 i 14 15 16 17 c The PURGE VENT BLEED hose may form condensation and or ice due to the temperature drop as CO exits the chamber Wipe any condensation from the PURGE VENT BLEED hose with a cleanroom wipe to keep it dry d During purge you will also notice oily currents in the chamber This is the intermediate fluid alcohol Record the total purge time on the log sheet The Samdri 795 will automatically advance to the HEAT cycle once the purge cycle is completed Make sure the chamber is completely filled with liquid CO2 If not press the FILL button again to ensure complete filling of the chamber During the heat cycle record both temperature and pressure on the log sheet in increments of one minute During the heat cycle you will notice a Schlieren patterns oily currents in the chamber caused by density variations of the CO in the chamber b Gradual increase in temperature and pressure of the chamber c The critical point for CO is at T 31 3 C and P 1072 psi The Samdri 795 has an automatic pressure valve that maintains the maximum pressure between 1200 1500 psi during heating Once critical point has been reached continue
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