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1/8 boost gauge line to 4mm vacuum line

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I have been trying to figure out a way to connect my 1/8 boost gauge line to the 4mm vacuum line. I have come across all sorts of fittings people have put together to accomplish this. I came across this fitting at work that SMC make called the Plug-in Reducer (part number:KQ2R23-04-X2). The 1/8 hard line coming out of the boost gauge plugs into the fitting and the vacuum line slips over the nozel.


This setup leaks out of the vacuum line and the vacuum line also pops off after 30PSI. There are two ways around this:

1) super glue the nozel before putting the vacuum line on and adding a hose clamp for added protection (suggest not to use zip tie as this was the first thing I tried to stop the leaking air and it only made it worse as it pinches the vacuum line). I tested this with only the super glue at work and ran up to 120PSI with no failure of the connection. I couldn't push it above this because the fitting from the vacuum line to the pump kept popping off above this pressure.

2) Buy the Plug-in Reducer (part number:KQ2R04-06-X2) and plug the 4mm nozzle into the 4mm plug in socket. This gives you a 6mm nozzle which will seal properly. Suggest to use a hose clamp on this one aswell. The 6mm nozel is the same diameter as the fitting I was using to connect the vacuum line to the pump. So if you are going to run 120PSI I wouldn't suggest doing this ;).


Sorry about the long write up but I wanted to cover everything.


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