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Goals:To remove loose dust and material from the primary mirror segmentsEquipment and Conditions Required:
Frequency:MonthlyTime Required:Approximately 2-3 hoursResponsible Party:Optical TechProcedure:The JLG should have the small basket attached so that you can enter the structure.The CO2 bottles should be staged by the garage door inside the enclosure. Put the cleaning wand in the JLG basket and attach it to the basket with a safety strap. String the hose along the boom. Tape the tygon tubing to the JLG boom. There should be one tube for each boom and one each in the middle and at the bottom of the lower boom. The hose should run freely through the tubing. Connect the hose to one of the CO2 bottles. Verify that CO2 snow/gas comes out of the wand. Using the JLG, the driver and operator should enter the structure and head for the top of the array. The ground support person should rotate the structure as required to allow entry and travel. Starting with segment 86, clean each segment with a left/right as well as an up/down pattern. It is easiest to clean the right side of the array first, then move the structure to allow cleaning of the left side. The ground support person should change bottles when ever the wand no longer shoots liquid. Typically this procedure requires six bottles to clean the array, however, sometimes a bottle is low on gas or the access tube is damaged and more bottles may be required. Upon completion of the cleaning, the CO2 hose/wand should be removed from the JLG and put back in storage. The empty CO2 bottles should be placed in the Empty Bottle Rack outside the spectrograph room. Full bottles should be returned to the Full Bottle Rack. The empty bottles should be returned to the supplier and new bottles ordered. Safety Precautions:
Notes:In the future the CO2 wand should have a ground wire inside the wand to aid in static charge dissipation.Keck actually heats their bottles to increase the pressure and to create more liquid. An eight bottle manifold with a permanent hose through the JLG cable wrap would allow easier operation for the ground support person as well as provide improved bottle security. Reflectivity measurements should be taken before and after cleaning so that you can quantify the change. See the procedure ???? for details. History:This procedure was first written up on 17 Sept 2002 by Jim Fowler.Return to Policy & Procedures |
Created: 2-May-2002 Send comments to: webmaster@het.as.utexas.edu |