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<p style="margin-top:0;margin-bottom:0">George,</p>
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<p style="margin-top:0;margin-bottom:0">I think you misunderstood where these Tubes need to be used. These 1/4" VCR Fittings are where the gas supply will attach. These tubes have to be 6mm OD in order to fit inside of and be glued to the Ring 1 of the cathode.
The 6mm OD Tube will then be welded onto a SS-4-VCR-3 Gland with a SS-4-VCR-1 Female nut attached. Utilizing the SS-4-VCR-6-400 fitting would then be THE way to go actually. I am working on the other side of the connections. (See attached pic of US End Plate
assembly) For the one 1/2" VCR Fitting there is an adapter available to go from VCR to 1/4"(SS-8-VCR-6-400), 3/8"<span>(SS-8-VCR-6-600)</span>, or 1/2"<span>(SS-8-VCR-6-810)</span> tube as well. </p>
<p style="margin-top:0;margin-bottom:0">VCR Fittings are used extensively in the SRF Institute and have been proven to very be reliable even to cryogenic temps. They also make servicing much easier.
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<p style="margin-top:0;margin-bottom:0"><span>I do not recommend NPT fittings for use on anything that will carry Helium.
</span>With NPT fittings you have the Epoxy issue that means you have to wait for it to cure on Installation and remove the epoxy for removal. Neither of which are necessary with VCR fittings. The exception to this might be a check valve or pressure gauge that
can not be ordered without a NPT fitting.</p>
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<p style="margin-top:0;margin-bottom:0">Thanks,</p>
<p style="margin-top:0;margin-bottom:0">Keith<br>
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<div id="divRplyFwdMsg" dir="ltr"><font style="font-size:11pt" face="Calibri, sans-serif" color="#000000"><b>From:</b> George Jacobs<br>
<b>Sent:</b> Tuesday, June 18, 2019 1:24 PM<br>
<b>To:</b> Carlos Ayerbe Gayoso; Keith Harding; dsg-rtpc@jlab.org<br>
<b>Cc:</b> Cyril Wiggins<br>
<b>Subject:</b> Re: Gas Tubes ID</font>
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<div>Is it possible to change from the 6mm VCR fitting to something that will more easily adapt it to the 1/4" nylon tubing that will be used to supply gas to the RTPC? My swagelock catalog does not show any metric to english adapters for this. If the connections
must be VCR, can they be 1/4"? Then we could adapt the 1/4" nylon tubing to 1/4" VCR using an available fitting, SS-4-VCR-6-400. Otherwise, we will need to weld up an adapter to make the connection.</div>
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<div>If we could eliminate the VCR fitting altogether, 1/8" FNPT or 1/4" compression could be used to replace the 6mm VCR fittings. While a 1/4 FNPT or 1/2" compression fitting could be used for the larger fitting.<br>
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<div>-- <br>
George Jacobs<br>
<span style="font-family:"Times New Roman",Times,serif">Jefferson Lab (TJNAF)</span><br>
<span style="font-family:"Times New Roman",Times,serif">STE 12</span><br>
<span style="font-family:"Times New Roman",Times,serif">12000 Jefferson Ave.</span><br>
<span style="font-family:"Times New Roman",Times,serif">Newport News, VA 23606</span><br>
<span style="font-family:"Times New Roman",Times,serif">(office) 757-269-7021</span><br>
<span style="font-family:"Times New Roman",Times,serif">(email) jacobsg@jlab.org</span></div>
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<div id="x_divRplyFwdMsg" dir="ltr"><font style="font-size:11pt" face="Calibri, sans-serif" color="#000000"><b>From:</b> Carlos Ayerbe Gayoso<br>
<b>Sent:</b> Tuesday, June 18, 2019 11:08 AM<br>
<b>To:</b> Keith Harding<br>
<b>Cc:</b> Cyril Wiggins; George Jacobs<br>
<b>Subject:</b> Re: Gas Tubes ID</font>
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Hi Keith, <br>
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I don't think that would be an issue, if I don't remember bad, the maximum flow to the RTPC is on the order of ~200-300 sccm, but I am forward this mail to George Jacobs, which is the real expert and the one who advice me about all the gas connections. </div>
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I am sorry for not being of greater (or immediately) help.</div>
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Cheers</div>
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-Carlos<br>
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<div id="x_x_divRplyFwdMsg" dir="ltr"><font style="font-size:11pt" face="Calibri, sans-serif" color="#000000"><b>From:</b> Keith Harding<br>
<b>Sent:</b> Tuesday, June 18, 2019 10:50 AM<br>
<b>To:</b> Carlos Ayerbe Gayoso<br>
<b>Cc:</b> Cyril Wiggins<br>
<b>Subject:</b> Gas Tubes ID</font>
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Carlos,</p>
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Question about the Gas Tubes on the VCR Fittings For the BONuS Target.</p>
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Currently on the 1/4" VCR Fittings we are specifying 6mm OD x .5mm Wall tube (5mm ID)</p>
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For weld-ability I would like to use 6mm OD x 1mm Wall tube (4mm ID) <br>
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I spoke to Bill Crahen about it and structurally there is no adverse effects. Is there any flow issues with decreasing the ID of the tube by 1mm? </p>
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Thanks,</p>
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Keith<br>
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