D420! How about that?

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Newest take off D420 is a winner after pool diving it this morning, I think SP has someone in the assembly department who has figured it out.
 
Great to see that the reviews have been good. The D-series has always been polarizing. Those who tried them tended to LOVE them. This is one “old design” i have been waiting to see return. (You never have to wait too long to see “an old friend” in diving)
 
FWIW I purchased a D420 back in March (and then sat and looked at it for months) before finally getting to dive in a lake here in the U.K.

I was curious as to how good it was and have been searching/ trying regs over the years to find a sweet easy breather.

Based on Mr Singlers’ you tube vids and people s comments and discussions here I thought I d give it a go.

It’s mated to a Mk25 (my first Mk25). I took down to 18m or so. Would have liked to take it below 30m to see how it coped but was limited by the geography.

All in all it breathed really easy. I have nt tinkered with it at all. Not one bit. Over the years I have used US Divers, Poseidon, Apeks, Scubapro (Mk2/R190) and am currently enjoying Atomics (B2s) by way of comparison.

Further research dives needed to make a side by side comparison to the B2s.

Not spanner handy to tune it.

As an FYI

(Now going into lockdown 2.0 tonight, so this will be a work in progress)
 
What always impressed me about D-series was how consistent the airflow was on inhalation. By that, I mean every other reg I've owned or breathed could "flutter" (for lack of a more illustrative term) a bit while delivering air. D's have always been like "Crack it open and the air just oozes out."

Does that dynamic sound like this new D420?
 
What always impressed me about D-series was how consistent the airflow was on inhalation. By that, I mean every other reg I've owned or breathed could "flutter" (for lack of a more illustrative term) a bit while delivering air. D's have always been like "Crack it open and the air just oozes out."

Does that dynamic sound like this new D420?
I have two new 420’s that would fit that description and two tuned from the first out batch which exceed that now but didn’t even come close when they were new.
 
Glad they are capable of being tuned "to perfection!"

Happy bubbles lex!
 
In this thread:
solution for D-series poppet seat DIY?
@Kupu came up with an ingenious solution to the variable quality/sealing performance of the D-400 seats: a Duro 50 silicone 2-104 oring.

I'm pleased to confirm that this works perfectly with the D-420 as well, as @lexvil has already proved.
20201024_134840.jpg

As discussed above, the orifice (housing) of the D420 is a little different in material and knife edge. But the silicone 104 sealed perfectly, and I was able to get cracking effort down to 0.5" easily (though as discussed above, you don't really want it there, but rather around 1.2").

Simply grasp the shaft of the existing poppet with pliers and unscrew the lock nut. Pull off the plastic cap and remove the seat and tiny oring.
As discussed here the o-ring performs better with a 1x3mm oring between the shelf of the poppet shaft and the 2-104 oring.
20201024_135045.jpg

So first put the 1x3 on, then the 2-104, then the tiny 1x2.5 that was under the cap. Put the cap back on and screw on the lock nut. Tighten it so that the 1x3 is visible to the extent in the picture below:
20201024_134928.jpg

Too loose or too tight and the 104 o‐ring doesn't seal as consistently.

This is one solution to the high cost of the new kits. Add your own orings and you have a kit for a few dollars, instead of the $60 list of the Service kit, IF your knife edge hasn't been dinged. If it has, then the housing is part of the Service kit. Lay in a few kits for the housings and some orings, and your D420 will last the same 30+ years that the D-series has.
 

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