HP Orifice for gauge flutter/whine on transfill whip?

[nw-diver]

Finally got in all the pieces and put my transfill whip together.

Works well, except:

at anything beyond very slow fill rate, the analog HP gauge on the supply side starts to hum and the needle starts to flutter. presumably this is due to the increased turbulence from higher air flow rate. the digital gauge appears unaffected, but probably only due to sampling rate, and I worry about wear on the sensor.

anyone know the means for addressing this? currently the gauges are both 1/4" MNPT going straight into a T on the fill whip on either side of a needle valve.

I think a Female to Male 1/4" NPT fitting with built in orifice might do the trick (one for each gauge), but need to find a good supplier that can handle say 4000psi working pressure.

any better solutions out there?

also looking for a venturi vacuum pump capable of drawing 20+ CFM using 90-150psi supply pressure (for second stage tuning). anyone know where an affordable one is available, or can point me to a good book/article on nozzle design for venturi pumps so i can make my own?

 

[rjack321]

A glycerine filled gauge will solve your needle flutter problem and be a bit more shock resistant too. A coarser dry gauge would also probably do it although you don't want to blasting gas through anyway, certainly not O2.

 

[pescador775]

I never heard of this problem. The gauge should come already fitted with a small orifice to reduce slam. What kind of gauge is it? "Analog" doesn't say much.

Don't know anything about vacuum pumps, well, there was a rumor about a sex toy.......or was that a cow milker?

 

[CraigAClark]

I never heard of this problem. The gauge should come already fitted with a small orifice to reduce slam. What kind of gauge is it? "Analog" doesn't say much.

Don't know anything about vacuum pumps, well, there was a rumor about a sex toy.......or was that a cow milker?

Hey Pesky,
When I order gauges, I have to specify that they have a "snubber" installed. I generally get 2.5" SS cased gauges from Wika, either liquid filled or dry. They have to be special ordered to get the snubbers.

Craig

 

[oxyhacker]

You can also buy gauge snubbers for about $5 from McM-C and others, which have either a tiny orifice or other restrictor, to use with your existing gauge.