I like them because they are small, don't require a deep hole (I usually drill 0.275 inches and use a bottoming tap), and don't use a tapered thread. The main thing is they need to have a good flat spotface for the o-ring to seal against. Early on, I was having o-ring blowouts and it was because I was using regular end mills to create the spotface. I switched to a using a counterbore tool and the problem went away. I'm using the Beswick series with Viton o-rings and they're good for a few uses in between changing out the o-ring. The main hassle is if you have a bunch of them stacked together (orifice + filter + compression fitting, etc.) you have to tighten up all of them sequentially without loosening any of them. They don't take a lot of torque to seal (9-12 in-lb) which is good. Beswick don't list pressure ratings but when I asked about one of the CF filters, one of their design engineers did an FEA run for me (wow) and said the limiting factor was the thread (safety factor of ~1 at 1500 psi). That doesn't seem right though because 1500 psi only generates 42 lbf of force and a #10-32 thread should be good to more than that.
I was hoping to use the CKV or CKVU check valves for the igniters but both valves (duckbill and umbrella style) have an elastomer as the moving component so I doubt it would take the temperature as a poppet check valve would. I'm currently using the Swaglok SS-2C-1/3 for that but it is way larger than I need. I saw O'Keefe had some metal-metal seat valves but I haven't inquired further. The metal-metal seat valves also aren't bubble-tight.
-Bob On 09/21/2014 04:01 PM, Ben Brockert wrote:
Robert, I also saw in your latest update that you're using 10-32 thread for igniter taps off your linked valve. I've seen 10-32 parts on McMaster but never tried using them, how have they worked for you? Any tips or tricks that you've found helpful? Ben
