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georgeaustin
Master Diver
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Joined: Mon Nov 04, 2013 8:41 am
First Name: george
Location: Los Angeles CA

Operations Questions: SP MKV / 108

Sun Aug 02, 2015 2:19 pm

So 1 year ago I installed the SP 108 service packs from VDH on my SP 108's and used the instructions to replace the soft seat and the O rings for the second stage, downstream valve, set the adjustable orifice / downstream valve as directed via the SP instruction data sheet. The MK V was just rebuilt 2 years ago but not used - stored in a plastic bag in a cool basement year round.

Yesterday I was setting up my rig that will be in pool sessions with dive prospects and other new divers - BP/W / MK V / 108 and just did some routine leak checks and checked the IP - IP locked on a 2,100 psi tank at 145 psi with no creep observed after 15 minutes under pressure- cycled purge valve on primary and octo (SP108 also) - looked fine.

Last night I went to Fisherman's Cove / Mermaid Grotto in Laguna Beach, CA. for a solo night dive.
Dive depth 32fsw X 62 minutes.
Started dive with 2100 psi
Ended dive with 200 psi
Vis. 10 ft / surgy at 20 ft and above
First dive since first / second stage service!
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Conditions:
The regulator delivered plenty of air from full tank to nearly MT but at times the air delivery was noticeably , well, "urgent" and seemed to "surge". This condition happened infrequently at varying tank pressures throughout the dive and seemed to be a little more noticeable in a head up position while inspecting the wall/reef. The surgy air delivery happened maybe 3 or 4 times total but was a little alarming as I have been diving nothing but my PRAM for the past 100 or so dives and have grown accustomed to its smooth delivery despite varying tank pressures and exertion levels in currents and what not.

Upon returning home I checked the IP on the reg and the same tank - (200 psi post dive) and the IP is a rock solid 125 psi.
I'm thinking I may have a downstream valve on the SP 108 slightly too hot?
Should I back out 1/8 of a turn? - Detune
The regulator does not hiss at all when connected to a full tank and pressurized, I might add.
_______________________________________________________________________________________

The conditions noted that I dislike are -
1.) Inhalation effort is a little too sensitive for my taste - the regulator feels "too anxious" to deliver the next breath
2.) The infrequent, surgy, almost "explosive" nature of the air delivery even with a tank pressure of 300 psi or even 200 psi.
3.) Since the first stage is coupled to the tank which is mated to a "tec" style BP, I feel that the tank strap slots push everything up too high or more accurately, bring the BP lower on the ST72 cylinder. - yes, I can easily reach my cylinder valve but I'm not always in a GUE style horizontal trip and I am annoyed by being able to snap my head back and feel that the first stage is too high.
4.) I can hear the first stage working during breathing cycles during the dive - I hate that.
________________________________________________________________________________________
Anyway, I am wholly unfamiliar with the MK V / 108 and its peculiarities - I understand the operational characteristics of the flow thru balanced piston design and how the downstream valve is intended to work however.
Maybe I'm just comparing apples to oranges WRT the PRAM and the MK V / 108.
Gimme back my double hose!! (not allowed with students in pool or open water)
Anyone have any thoughts?
Thanks,

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georgeaustin
Master Diver
Posts: 272
Joined: Mon Nov 04, 2013 8:41 am
First Name: george
Location: Los Angeles CA

Re: Operations Questions: SP MKV / 108

Sun Aug 02, 2015 4:58 pm

Cracking at 0.063 psi - 1.75 inch - that's a little light as the SP booklet calls out between 2 and 3 inches of water - ( really ? )
As well, after further review of Chapter 7 Section 1 of Regulator Savvy (Pete Wolfinger) right, I had it bassawkwards, Stiffen spring load by turning CW the orifice in DS valve to dampen erratic water impulse action on second stage -

I wonder if the surging was just caused by the light cracking second plus the surgy beach diving conditions last night?

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Bryan
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Joined: Fri Jun 24, 2005 11:40 am
First Name: Bryan
Location: Wesley Chapel Florida
Contact: Website

Re: Operations Questions: SP MKV / 108

Sun Aug 02, 2015 5:08 pm

Sounds like you have found your answer......The 108 while lacking some finesse is one of the most reliable, low maintenance 2nd stages ever built. I would move it over and use it as a safe 2nd and put a 109 in the primary spot. Never heard a MK5 making noise....Perhaps Luis or Couv can shed some light on that issue.
Doing it right should include some common sense, not just blindly following specs and instructions. .Gary D, AWAP on SB

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georgeaustin
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Posts: 272
Joined: Mon Nov 04, 2013 8:41 am
First Name: george
Location: Los Angeles CA

Re: Operations Questions: SP MKV / 108

Sun Aug 02, 2015 5:55 pm

The 108 is comfortable enough I suppose and I have tuned the Octo 108 to about .090 inches- I should have switched and noted the differences if any but the primary probably would have free flowed intermittently.
Yeah, well I had a MK10 with two converted 109's but - uh - um -
Seems I gave that rig to a very beautiful but very poor Mexicana divemaster in Baja.
Ask me what I got in return - zip, zero, nada. Lessons Learned

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georgeaustin
Master Diver
Posts: 272
Joined: Mon Nov 04, 2013 8:41 am
First Name: george
Location: Los Angeles CA

Re: Operations Questions: SP MKV / 108

Sun Aug 02, 2015 11:14 pm

.090 psi I meant to write

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Bryan
Plank Owner
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Joined: Fri Jun 24, 2005 11:40 am
First Name: Bryan
Location: Wesley Chapel Florida
Contact: Website

Re: Operations Questions: SP MKV / 108

Mon Aug 03, 2015 5:10 pm

You might try just the 2nd stage on your Phoenix to see if it changes. After some thought. A bad or poorly lubricated piston O ring MIGHT be the cause of your 1st stage sound. Often they get replaced with 70 durometer standard Orings which extrude too easily. Should be 90 durometer. Just guessing since I have not seen it in person.

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Doing it right should include some common sense, not just blindly following specs and instructions. .Gary D, AWAP on SB

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