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Re: [VacuumX] Pump manuals

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  • James Blackett
    Well, I was not getting anywhere, so I decided it was time to look inside. I stripped the pump down and found a couple of things wrong; the first was straight
    Message 1 of 16 , Jul 6 9:50 AM
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      Well, I was not getting anywhere, so I decided it was time to look inside. I stripped the pump down and found a couple of things wrong; the first was straight forward (and thanks to those who pointed me in the right direction), the oil was a bit 'gloopy' and there was debris in the bottom of the pump. I gave it a good clean and some new oil. The second was that this rotary vane pump must have been made in the dark ages, the position of the rotor and the outer casing is adjustable, although how your supposed to adjust it I don't know. When I took it apart there was a large gap between the low and high pressure chambers, so the pump was short circuiting itself. I reassembled the unit with as narrow a gap as I dared and ran it up. Bingo! it now works a treat, although I cant measure the ultimate vacuum; I'll look at purchasing something suitable in the near future. (The pump claims 0.01 mbar, but I doubt a single stage pump will achieve that in practice). The oil I used wasn't vacuum pump oil, as it was a bit pricy; as I had a source of compressor oil (as in airconditioning compressors), I used that, reasoning that it should have a relatively low vapour pressure to work ok in a compressor. Does anyone have experience using this type of oil?
       
      anyway thanks for your advice and help,
       
      regards
       
      James
      ----- Original Message -----
      Sent: Wednesday, June 23, 2010 4:45 PM
      Subject: Re: [VacuumX] Pump manuals

       

      All,
       
      many thanks for your suggestions, I'll check through what you have said and get back to you with the results,
       
      James
      ----- Original Message -----
      From: SVC
      Sent: Wednesday, June 23, 2010 3:29 PM
      Subject: Re: [VacuumX] Pump manuals

       

      If you have a sight window look to see if the oil lever is up to the mark.  If it is that old I would drain and replace the oil.


      Make sure the ballast valve is not fully open so you are not just pumping through the valve and not the system. I would start with the valve fully closed and then if you have trouble with water getting in your oil and making it froth up and lose pumping speed you can begin opening he valve is stages. It is best to let in dry air if it is available.

      Don



      Hi all,
       
      I'm new to this group - looks like some of you have some fancy rigs I could only dream of. AnywayI've just dug out a very old Edwards single stage speedi-vac pump, model 1sc50, which has been on the shelf for many years. When I started it up, it did not produce hardly any vacuum ( only an absolute pressure of about 600 mbar, which is useless!!!). Before I start stripping it down, I was wondering if anyone had or could point  me towards a manual? This pump is probably around 50 years old, but I remember it being refurbished by Edwards around 1975 and it hasn't been used since then.
       
      many thanks in anticipation,
       
      James




      -- 
      
      ____________ _________ _________ ______
      Donald M. Mattox
      Society of Vacuum Coaters
      71 Pinon Hill Place NE
      Albuquerque, NM  87122-1914

      Telephone 505/856-7188
      FAX 505/856-6716
      E-mail donmattox@svc. org
      WebSite  http://www.svc. org

    • Guy Brandenburg
      Our old no-name, government-surplus diffusion pump has a problem. After pumping the diff pump for a while (minutes or hours, doesn t seem to make a difference)
      Message 2 of 16 , Dec 26, 2010
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        Our old no-name, government-surplus diffusion pump has a problem. 
        After pumping the diff pump for a while (minutes or hours, doesn't seem to make a difference) and after loading the mirror to be coated into the bell jar, this is what happens:
        when I close the connection between the mechanical pump and the diffusion pump, and begin pumping down the bell jar directly, the pressure in the diffusion pump all of a sudden rises dramatically, going up to ~200 millibars if I don't immediately switch back to pumping down the diffusion pump directly again. It becomes quite a dance, closing one valve then opening the other, then reversing again, and again, and again.
        Eventually it always settles down and I get decent vacuum levels, but it's annoying for a while.
         
        Guy Brandenburg, Washington, DC 

        My blog, mostly on Education in DC:
        http://gfbrandenburg.wordpress.com/


        My home page on astronomy, mathematics, education:
        http://home.earthlink.net/~gfbranden/GFB_Home_Page.html
        or else   
        http://tinyurl.com/r6fh2
        =====================================



      • James Blackett
        Hi, this seems very weird, I dont understand!! 200 mb is very high. Can you pump the bell jar down without bypassing the diff pump? what happens then? Because
        Message 3 of 16 , Dec 26, 2010
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          Hi,
           
          this seems very weird, I dont understand!! 200 mb is very high. Can you pump the bell jar down without bypassing the diff pump? what happens then? Because you can achieve a good final vacuum (how much?), there cant be too much wrong with your system, I wonder if there is someting wrong with the gauge(s), I've seen some pirani gauges do stupid things when they have been contaminated,
           
          sorry this is not much use, but just my ramblings,
           
           
          James
          ----- Original Message -----
          Sent: Sunday, December 26, 2010 8:48 AM
          Subject: [VacuumX] weird diffusion pump behavior

           

          Our old no-name, government-surplus diffusion pump has a problem. 
          After pumping the diff pump for a while (minutes or hours, doesn't seem to make a difference) and after loading the mirror to be coated into the bell jar, this is what happens:
          when I close the connection between the mechanical pump and the diffusion pump, and begin pumping down the bell jar directly, the pressure in the diffusion pump all of a sudden rises dramatically, going up to ~200 millibars if I don't immediately switch back to pumping down the diffusion pump directly again. It becomes quite a dance, closing one valve then opening the other, then reversing again, and again, and again.
          Eventually it always settles down and I get decent vacuum levels, but it's annoying for a while.
           
          Guy Brandenburg, Washington, DC 

          My blog, mostly on Education in DC:
          http://gfbrandenburg.wordpress.com/


          My home page on astronomy, mathematics, education:
          http://home.earthlink.net/~gfbranden/GFB_Home_Page.html
          or else   
          http://tinyurl.com/r6fh2
          =====================================



        • Guy Brandenburg
          BTW I haven t been able to photograph the haze that sometimes occurs because it hasn t occurred. Guy ________________________________ From: Guy Brandenburg
          Message 4 of 16 , Dec 26, 2010
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            BTW I haven't been able to photograph the haze that sometimes occurs because it hasn't occurred. 

             
            Guy 


            From: Guy Brandenburg <gfbrandenburg@...>
            To: VacuumX@yahoogroups.com
            Sent: Sun, December 26, 2010 3:48:42 AM
            Subject: [VacuumX] weird diffusion pump behavior

             

            Our old no-name, government-surplus diffusion pump has a problem. 
            After pumping the diff pump for a while (minutes or hours, doesn't seem to make a difference) and after loading the mirror to be coated into the bell jar, this is what happens:
            when I close the connection between the mechanical pump and the diffusion pump, and begin pumping down the bell jar directly, the pressure in the diffusion pump all of a sudden rises dramatically, going up to ~200 millibars if I don't immediately switch back to pumping down the diffusion pump directly again. It becomes quite a dance, closing one valve then opening the other, then reversing again, and again, and again.
            Eventually it always settles down and I get decent vacuum levels, but it's annoying for a while.
             
            Guy Brandenburg, Washington, DC 

            My blog, mostly on Education in DC:
            http://gfbrandenburg.wordpress.com/


            My home page on astronomy, mathematics, education:
            http://home.earthlink.net/~gfbranden/GFB_Home_Page.html
            or else   
            http://tinyurl.com/r6fh2
            =====================================




          • Daryl P. Dacko
            Just a guess, but that sort of behavior has been linked to a weak heater on the diff pump. The pump oscillates between backstreaming and proper behavior. It s
            Message 5 of 16 , Dec 26, 2010
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              Just a guess, but that sort of behavior has been linked to a weak
              heater on the diff pump.
              The pump oscillates between backstreaming and proper behavior.

              It's a long shot, but it's been known to happen...

              Daryl
            • Guy Brandenburg
              A weak heater, and not a hyperactive, too-hot one? Hmm. Sent from my iPhone
              Message 6 of 16 , Dec 26, 2010
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                A weak heater, and not a hyperactive, too-hot one? Hmm.

                Sent from my iPhone

                On Dec 26, 2010, at 9:12 AM, "Daryl P. Dacko" <mycrump@...> wrote:

                 

                Just a guess, but that sort of behavior has been linked to a weak
                heater on the diff pump.
                The pump oscillates between backstreaming and proper behavior.

                It's a long shot, but it's been known to happen...

                Daryl

              • Guy Brandenburg
                I suppose I could, theoretically, pump both the bell jar and the diffusion pump at the same time, but I think it would be a bad idea since the dp would rise to
                Message 7 of 16 , Dec 26, 2010
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                  I suppose I could, theoretically, pump both the bell jar and the diffusion pump at the same time, but I think it would be a bad idea since the dp would rise to 1atm for a while.
                  We get down to about 
                  ~9 to 7*10^-5 torr. Can't seem to go any lower. The coatings look good and seem to last a reasonable length of time (years).

                  Sent from my iPhone

                  On Dec 26, 2010, at 8:16 AM, "James Blackett" <jamesrblackett@...> wrote:

                   

                  Hi,
                   
                  this seems very weird, I dont understand!! 200 mb is very high. Can you pump the bell jar down without bypassing the diff pump? what happens then? Because you can achieve a good final vacuum (how much?), there cant be too much wrong with your system, I wonder if there is someting wrong with the gauge(s), I've seen some pirani gauges do stupid things when they have been contaminated,
                   
                  sorry this is not much use, but just my ramblings,
                   
                   
                  James
                  ----- Original Message -----
                  Sent: Sunday, December 26, 2010 8:48 AM
                  Subject: [VacuumX] weird diffusion pump behavior

                   

                  Our old no-name, government-surplus diffusion pump has a problem. 
                  After pumping the diff pump for a while (minutes or hours, doesn't seem to make a difference) and after loading the mirror to be coated into the bell jar, this is what happens:
                  when I close the connection between the mechanical pump and the diffusion pump, and begin pumping down the bell jar directly, the pressure in the diffusion pump all of a sudden rises dramatically, going up to ~200 millibars if I don't immediately switch back to pumping down the diffusion pump directly again. It becomes quite a dance, closing one valve then opening the other, then reversing again, and again, and again.
                  Eventually it always settles down and I get decent vacuum levels, but it's annoying for a while.
                   
                  Guy Brandenburg, Washington, DC 

                  My blog, mostly on Education in DC:
                  http://gfbrandenburg.wordpress.com/


                  My home page on astronomy, mathematics, education:
                  http://home.earthlink.net/~gfbranden/GFB_Home_Page.html
                  or else   
                  http://tinyurl.com/r6fh2
                  =====================================



                • Vladimir Chutko
                  Guy, What do you mean: when I close connection between the mechanical pump and the diffusion pump ? If you close backing valve and open gate valve, system
                  Message 8 of 16 , Dec 26, 2010
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                    Guy,

                    What do you mean: "when I close connection between the mechanical pump and the diffusion pump"? If you close backing valve and open gate valve, system won't work.  Only cryo and other sorption pumps work with closed backing valve. Dif and turbo pumps must be backed always.

                    Do you have gauge on the dif pump input flange under the gate valve and on its output? What are the pressures?

                    Sometimes valves may leak in some position, for instance, there is no leak when it closed and a great leak when it opened. So everything looks fine when a gate valve is closed, and a big leak appears when you open it for high vacuum pumping.

                    Best regards,

                    Vladimir

                    On 12/26/2010 12:48 AM, Guy Brandenburg wrote:
                    Our old no-name, government-surplus diffusion pump has a problem. 
                    After pumping the diff pump for a while (minutes or hours, doesn't seem to make a difference) and after loading the mirror to be coated into the bell jar, this is what happens:
                    when I close the connection between the mechanical pump and the diffusion pump, and begin pumping down the bell jar directly, the pressure in the diffusion pump all of a sudden rises dramatically, going up to ~200 millibars if I don't immediately switch back to pumping down the diffusion pump directly again. It becomes quite a dance, closing one valve then opening the other, then reversing again, and again, and again.
                    Eventually it always settles down and I get decent vacuum levels, but it's annoying for a while.
                     
                    Guy Brandenburg, Washington, DC 

                    My blog, mostly on Education in DC:
                    http://gfbrandenburg.wordpress.com/


                    My home page on astronomy, mathematics, education:
                    http://home.earthlink.net/~gfbranden/GFB_Home_Page.html
                    or else   
                    http://tinyurl.com/r6fh2
                    =====================================



                  • Guy Brandenburg
                    In our setup, the mechanical pump has tubes and valves that connect either to the bell jar or to the rear end of the diffusion pump. I ll have to see exactly
                    Message 9 of 16 , Dec 26, 2010
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                      In our setup, the mechanical pump has tubes and valves that connect either to the bell jar or to the rear end of the diffusion pump.
                      I'll have to see exactly where the gauge for the dp is located.

                      Sent from my iPhone

                      On Dec 26, 2010, at 3:30 PM, Vladimir Chutko <chutko@...> wrote:

                       

                      Guy,

                      What do you mean: "when I close connection between the mechanical pump and the diffusion pump"? If you close backing valve and open gate valve, system won't work.  Only cryo and other sorption pumps work with closed backing valve. Dif and turbo pumps must be backed always.

                      Do you have gauge on the dif pump input flange under the gate valve and on its output? What are the pressures?

                      Sometimes valves may leak in some position, for instance, there is no leak when it closed and a great leak when it opened. So everything looks fine when a gate valve is closed, and a big leak appears when you open it for high vacuum pumping.

                      Best regards,

                      Vladimir

                      On 12/26/2010 12:48 AM, Guy Brandenburg wrote:

                      Our old no-name, government-surplus diffusion pump has a problem. 
                      After pumping the diff pump for a while (minutes or hours, doesn't seem to make a difference) and after loading the mirror to be coated into the bell jar, this is what happens:
                      when I close the connection between the mechanical pump and the diffusion pump, and begin pumping down the bell jar directly, the pressure in the diffusion pump all of a sudden rises dramatically, going up to ~200 millibars if I don't immediately switch back to pumping down the diffusion pump directly again. It becomes quite a dance, closing one valve then opening the other, then reversing again, and again, and again.
                      Eventually it always settles down and I get decent vacuum levels, but it's annoying for a while.
                       
                      Guy Brandenburg, Washington, DC 

                      My blog, mostly on Education in DC:
                      http://gfbrandenburg.wordpress.com/


                      My home page on astronomy, mathematics, education:
                      http://home.earthlink.net/~gfbranden/GFB_Home_Page.html
                      or else   
                      http://tinyurl.com/r6fh2
                      =====================================



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