fun failure today

rdmmdr

hi

i got back my mk20 from service that i use a for my o2 side and had to try it out. quick run to 200 ft and then back up. about 180 hud go off/ flashing yellow and handsets tell me i'm at 1.0po2/ set point 1.2, while accending. display is showing solinoid is firing but no noise. hit the manual and keep accending, solinoid starts firing again but stops again at about 100 ft. fly manually to 30ft solioinoid working intermitantly for the rest of the dive keep having the hit the manual add about every three mins. Yes it was an ip creep failure, o2 solinoids don't work at higher pressures. i know that this is a problem and have been looking for a opv that can be adjusted to a lower cracking pressure say 175psia, does any body know of a supplier. all of the argon ones that i have found are set for about 300 psia. all that does is protect the hoses. by the way i think that my buddy was more worried then i was hand sets flashing , hud showing yellow, his eyes the size of dinner plates. i looked like a christmas tree. primary controller was pisssed about the injection failure so it was screaming. yes i need to put a time out in the system to shut off the alarm.


my controllers have no buttons the mag switches are played with on the surface with magnets and dont need to be played with in dive mode. so had included no option to shut off the alarms. on fresh charges i have 20 hrs of battery life so power budget allowed for the alarms. but my sanity did not.

tower to pilot " did you not hear us tell you that your landing gear was not down"
pilot to tower" i could not hear you over the g-d d--m horn"

rick

johnv

With respect, I would suggest that having an OPV so it can vent you O2 into the water but keep the soleniod working is not a great idea.

venting O2 is preferable to hoze burst, but I'd rather keep my O2 and have to use manual. (or switch backup O2 to the manifold). venting O2 to make life easier doesn't seem a good solution.

just a thought
John

rdmmdr

if you have a hp seat failure it will result in an ip rise that will lift a 300psi opv. the only reason it had not lifted was that i was using the mav to decrease pressure in the system. i would have heard the leak or my buddy would have pointed it out to me. while i had a single point failure, and had trained for it. i think that a backup that would allow the rest of the system to work, is a better option. while i solved the problem is this the way to go. i enter the water with a minimum of ten hours of o2, a little leak will not kill me. a controller failure while narced could. i don't belive that alex's system for reduntant controls is the way to go, but having some backup is resonable.

rick

abowie

To be perfectly honest I personally don't think a Mk 20 is a good choice for your O2 reg.

The HP piston O ring arrangement includes a cylindrical locating collar made of cheap plastic which is a fiddle to fit and can be cracked by an inexperienced or ham fisted tech. The one I fixed for CD had an IP of 275psi.

Chuck it out and use a diaphragm reg or go for something simple and robust like a Mk 2 or Mk 10+.

__________________
Andrew Bowie

Rebreather-friendly Buddy

jradomski

Rick,
The ones sold by APD for the oxygen first stage are 14 bar (~200 psi)..

If you have an ANDI facility near you you can get them to order an adjustable OPV.. I dont remember the exact range but I know it can be set below 100psi on the low end..

__________________
Joe Radomski
CCR Trimix Instructor Trainer
ANDI Instructor Trainer Director #10

All posts are personal opinions and DO NOT reflect any affiliated agency unless specifically stated.

rdmmdr

i appreciate your sentiment but since i have already had one o2 fire all off my regs are certified by the manufacture for o2 use. that reg had over 500 hrs on it before i sent it in for service. the problem is not the reg it was the people that put it together. my only real bitch with scubapro is the support you get from their dealers.


but lets get back to the problem at hand, and that was not the hp seat failure. it was the fact that the solenoid's don't work with a hp seat failure, and how do we fix this. for me it was a pain in the a--, with the alarms going off. it was not a life critical problem and i would not figure it to be a serious structural problem because the 300psi opv will lift prior to the solenoid casing failure. and all my LP system with the exception of the solenoid can handle 3000 psi without a problem. what we need is a adjustable opv that will allow the solenoid to work if we get a hp seat failure. That was what i was trying to say, i was not slamming on the mk20 i like it it works. but be careful when the individual parts come back from service.

rick

rdmmdr

thanks joe
i will call them
rick

Helium_diver

Rick ,
Dive rite express has them . Look under regulator accessories. Says they are adjustable to any pressure you like.

Helium_diver

__________________
"If I look unconscious I probably am " Bill Hartman

abowie

Indeed and the Mk 20 is susceptible to being cocked up in that fashion on repair. If you want to see what I mean pull it apart and then try to replace the HP stem o ring and the bits that hold it in place.

There are plenty of other regs suitable for the task. The Mk 2's are O2 certified, and I believe the Mk 10+ without the knife edge piston is suitable as well. Then there are a whole gamut of diaphragm regs made by Zeagle, Mares, Apeks etc.

__________________
Andrew Bowie

Rebreather-friendly Buddy