New HPR 2nd Stage and Diverter Mouthpiece from The Scuba Museum
The HPR Second Stage Upgrade is BACK!
My Latest Double Hose Regulator Build...
- Rob's Scuba Museum has put the original "HPR" second stage upgrade back into production. This little unit makes super tuning your DA AquaMaster or Royal AquaMaster much easier. And their latest "Diverter Mouthpiece" takes the whole project a step further. So here's how the Super Tuning Process works (as I understand it)...
1. Reduce the "Cracking Effort" by reducing the spring tension on the 2nd stage seat.
2. Increase the Venturi Flow affect by blocking the bleed air ports (aka secondary ports)
Cracking Effort
- This is the minimum inhale effort to open the seat and feed air thru the mouthpiece. It's measured in INCHES of Water Column because original instruments worked off a column of water. Nowadays we use a Magnehelic gauge...
And, you hook the magnelhelic to the mouthpiece of your regulator. Here's my magnehelic hose setup.
- Before adjusting, I measured my cracking effort on the magnehelic and it was 1.7 inch wc. Then to adjust it, I backed the HPR body out 1/2 turn and measured again. It came down to 1.4 inch WC. So, I backed the HPR out another half turn but this made it leak air. Now, I was aiming for .5 inch wc so I'm at a road block. I called Luis Heros and he asked if my High Pressure diaphragm was old and stiff. So I opened up the first stage and looked...
- If your HP Diaphragm looks like the one above, it's time to put in a new one! I did that and was able to tune the cracking effort down to .7 inch wc! So, that part of the Super Tune was good enough for me!
Increasing Venturi Flow
- The Venturi flow is when the air comes out of the 2nd stage fast enough to create a sort of vacuum that's powerful enough to hold the 2nd stage seat open and cause a free flow from the Primary port. The Secondary ports are more accurately called "Bleed Air Ports" because they bleed air away from the Venturi and provide a way to control the flow. So if you want to adjust the Venturi flow you can block the Bleed Air Ports to a greater or lesser degree. The problem is that blocking just one of the ports on an original DAAM 2nd stage causes it to free flow out of control. You can hand make adjustments like drilling smaller Bleed Hole Ports. But the HPR makes it a lot easier than that. And so does the new flow Diverter mouthpiece... It can handle more Venturi flow without free flowing uncontrollably.
- Our first flow diverter mouthpiece was the DSV from the VDH Kraken regulator. This new Diverter Mouthpiece from the Scuba Museum is even MORE capable. I spoke with Luis Heros and he gave me a rule of thumb approach...
1. If you have a stock mouthpiece, don't block the Bleed Air Ports
2. If you have a DSV mouthpiece, just block ONE of the Bleed Air Ports
3. With the new Diverter Mouthpiece, you can BLOCK BOTH Bleed Air Ports.
The HPR can be mounted without blocking either of the Bleed Air Ports. To add in some blockage, use nylon hex nuts. These nuts can be fine tuned by beveling the blocking face to get a partial block of a bleed air port. Really the sky is the limit on how much fine tuning the HPR and Diverter mouthpiece allow you to do.
Make it Easy on Yourself
- Super Tuning involves a lot of taking apart and putting back together. I found that a band clamp with the Voit type thumb screw closure makes this a lot easier. I think the Scuba Museum has both of these items...
Finished Reg is a Super Easy Breather...
Note:
NEVER breathe directly
from the horn of a double hose regulator!
The new Diverter Mouthpiece...
1. Internal Flow Diverter allows super tuning Venturi flow... If you want to.
2. Includes one (1) removable mouthpiece...
- Fits many styles and sizes of standard mouthpieces.
3. Fits DA AquaMaster Hoses.
4. Comes in Attractive Colors.
