Poppet engraving prevention

[Kendall Raine]

For years I have used a rubber band and wad of paper (so sophisticated, I know) to keep the purge button slightly depressed when storing G250s in order to reduce the degree of poppet engraving inherent on the G250 poppet material. I know others use more sophisticated tools, but the objective is the same (relieve constant contact pressure on the poppet against the orifice to reduce incidence of free flow after long storage), but my method seems to work. I have never used this technique on Apeks seconds (TX 50s and ATX 100s) since they seem to sit happily for years without the same engraving induced free flow. My understanding is this is due to Apeks using a higher durometer material (greater engraving resistence) for their poppets than what SP uses.

My question is whether using that storage method eventually compresses/deforms the poppet spring inside the barrel thereby changing the second stage tuning/performance? While it may be worth it (extending the service interval) with the G250, in the case of the Apeks is this a case of "it it ain't broke don't fix it" or is there benefit to keeping the purge depressed (slightly) during storage?

For the record, I do not like the Atomic wave spring solution because I use my seconds intercgangably between back gas and stage/deco bottles so having the wave spring makes the first stage vulnerable to flooding if the reg is depressurized under water.

Thanks,

 

[Eric Sedletzky]

I was told by Couv years ago that any of those SP regs that use an S wing poppet like the G250 G200B, converted 109, 156, etc. have a really light spring and if you have them adjusted really light (high performing) plus have the knob turned all the way out (except for the G200B) the pressure will be very light, so light In fact that the poppet barely presses on the volcano orifice when not pressured. As soon as you pressurize those balanced seconds is when the balance chamber will push it shut tight. The super light spring and the fact that the poppet is pneumatically operated is what makes it such a wonderful breather down to almost no tank pressure.
Will keeping the purge open result in less indentation? Probably, but not as bad as a regular unbalanced poppet like a R190 or something.
The only ones I fret about being held open are the old 109’s because the rubber purge cover gets distorted and they are hard to find, good ones anyway.

 

[rhwestfall]

The only ones I fret about being held open are the old 109’s because the rubber purge cover gets distorted and they are hard to find, good ones anyway.

that is why you find the old ScubaPro blue keys, or buy James' [ @James79 ]reproduction keys. Holds the diaphragm & lever in to back off the seat, but the rubber faceplate stays in the state it was meant to be, not then taking on ugly and damaging set...

 

[The Chairman]

Just detune the reg so that the poppet doesn't even touch.

 

[Nemrod]

Just detune the reg so that the poppet doesn't even touch.

Exactly, if the regulator is hot tuned so that it barely (almost inaudible) leaks with the knob full out, then when the regulator is not in use the poppet and seat will not be against the orifice with enough force to indent. Effectively a seat saver by default.

 

[rhwestfall]

yes, how "we" can do that on our own. However, try and get a shop to do that.... It likely isn't within "manufacturer's specifications", so they won't do it.

Interesting conundrum...

 

[Still Kicking]

Splurge on an inline adjuster (if you don't have one) and detune your reg before storage and tune it again before use. It's a great tool to have anyway.

 

[Kendall Raine]

Just detune the reg so that the poppet doesn't even touch.

Exactly, if the regulator is hot tuned so that it barely (almost inaudible) leaks with the knob full out, then when the regulator is not in use the poppet and seat will not be against the orifice with enough force to indent. Effectively a seat saver by default.

OK, now you guys are hurting my pointed little head.

Intuitively I would have thought "detuned" and "hot tuned" would be opposites-that is "detuned" would be something like >1.5" while hot tuned would be something like <1.1". The idea of setting the cracking pressure below spec (e.g. 0.8" aka hot tuned)) makes intuitive sense from a seat saver perspective.

 

[rhwestfall]

Pete did appear to use the wrong term...

 

[Still Kicking]

I would think tuned is "just right" whatever that means to you .... anything more or less is detuned.