Steam Machine Prizm?

[scuubaadoo]

Just came back from Beneath The Sea show. Had a long talk with the people at Inspiration and Steam Machine. Really like the Steam Machine, the idea of being able to dive it without electronics seems so safe as a back up. And they even put a cover on it, looks real slick ( yeah yeah, least important reason to buy one). Any one using these rb's would like more info from some one not trying to sell these ( or best friends of some one trying to sell them).
Thanks

 

[padiscubapro]

being able to "dive" it without electronics isn't a sure fire thing as you might expect..

The secondary runs directly off the cells, these are custom high output cells also and must be purchased from steam machines.

This is no better or worse than any other rebreather that has an independent system.. The hammerhead electronics for the inspiration will read 3 cells simulatenously.. each display has it own power source so its basically the same as one driven by cells.. the inspiration has independent power source, each controller has its own battery.. so one dead battery doesn'y kill the unit...

one might say what if you flood the battery compartment?? yes both batteries are shot, but if water got this far, so is the loop, and most definately the cells, if this happened on a prism youd be off the loop also since the cells would also be shot...

The only thing I prefer on the prism is the scrubber itself, in my opinion the prsim electronics are too limited, but talking with peter it seems in certain circumstances he is willing to produce a less user limited controller.

I have seen major problems on the one unit I saw in use, but I'll reserve judgement until I dive with another diver with one because of the person who had issues isn't the best point of reference..

There is somone who is preparing to release a new scrubber for the inspiration which should have a much longer rated duration, correcting the one downside I see for those doing extremely long single dives. There is also another company working on a easily changeable scrubber with a duration of at least 4 hours(rated at 1.6lpm of CO2).

I don't know about the current electronics but I do know the set I got to examine was a modified version of Juergensen marine's very early mk 15 electronics(designed by will smithers).. (how do I know this?? I woun't say whose rb was examined but The code for the controller was removed and its virtually identical to Kevin's early stuff)..

The inspiration rates the scrubber at 180 mins @ 1.6lpm co2, the official rated duration for the prism is 4 hours at 1.35 lpm co2, scaleing it to 1.6lpm its only 3 hrs 22 mins.. just slightly longer than an inspiration, it also uses 6lbs of scrubber as opposed to 5.5lbs for the inspiration..

for divers not using helium based mixes the radial scrubber of the prism is a potential downside with regards to WOB (work of breathing), Radial scrubbers theoritically have a higher efficiency rating but one side effect is higher breathing resistance.


I tried to be as fair as possible with the comparisons...

You should also consider the Megladon, the current electronics was done by will smithers and is basically the same as the juergenmson marine mk15 electronics (3 gen I believe)..

If scrubbber duration is an issue this would be the best choice since it can be ordered (last time I checked) with a cis lunar scrubber which is a water tolerant very long duration scrubber..


I don't knwo if you stopped by the ANDI booth but my Modified rig was on dispay.. Christina Young has some pics on her web page..

 

[wazza]

The British army or the Americans are using the MK15 I saw them on TV 2 days ago ….

 

[scuubaadoo]

see your rig. I was helping at a booth and could only take short trips onto the floor (downside to working a show). How about the fact that the gas is mixed (don't shoot me if I have this wrong) pre-loop?Also what kind of breathing rate are we talking about here, some numbers are what I call workbench numbers only, very impressive but not real meaningful in real life. Looks like every answer leads to a new question.

 

[wazza]

Just asking a question, why every one here come and talk about any other ccr unit than the inspiration, he get kicked in the ass ehehehe
. Like the inspiration is the only or the best machine ever, don’t we have a better machines or what?.
talking about the inspiration can I change both reg and use any other kind of reg and should I change the intermediate pressure to 7.5 bar for both, or only the o2 reg..and is it important that if they are balanced reg or not, what kind of reg could be good to use. I am thinking of the TX50 maybe. Thanks for the help.

 

[madmole]

Only O2 side needs to be 7.5 bar. Any reg that can go this low will do. (Not many will)

Dil side can be any pressure, but if you ve still got the Auto Air this needs to be set up properly for the pressure you feed it or it will free flow

Why change them though, they are already Apeks 1st Stages and work fine. Nobody has issues or problems with them

 

[wazza]

Don’t u think its better to take the auto air off from the inflator and add a second stage from the reg directly?
And what are the reg that could go to 7.5 bar, does the TX50 works .
Madmole just asking for the knowledge more then I want to change them, though I have leak still in the O2 reg and I will open to see what is going on, its more likely an O ring, so what type of Apeks reg they are in the inspiration?
Thanks for the help.

 

[padiscubapro]

scuubaadoo once bubbled...
see your rig. I was helping at a booth and could only take short trips onto the floor (downside to working a show). How about the fact that the gas is mixed (don't shoot me if I have this wrong) pre-loop?Also what kind of breathing rate are we talking about here, some numbers are what I call workbench numbers only, very impressive but not real meaningful in real life. Looks like every answer leads to a new question.

not exactly sure what you are asking but here goes..

both the inspiration and prism inject gas before the inhale hose leading to the diver's DSV the exact injection point is different but serves the same purpose..

On the inspiration the automatic oxygen addition is added in the scrubber lid which is forced into the inhale lung to mix before returning to the inhale hose to the dsv. the prism injects the gas before the scrubber..

they both have their advantages, the prism has a slightly longer mixing duration but has the negative effect of adding drier gas into the scrubber (the scrubber needs moisture to work to create carbonic acid which is the first phase of co2 removal).

The inspiration injects after the scrubber, so mixing is shorter (but should still be complete), the down side is that the inspiration might momentarily display a PO2 higher than actual..

on just about any rebreather a good point can be turned to a bad point just as easily.. Its all about trade offs... I will say the current prism looks much better than had in the past.. My previous feeling about the prism is that it looked like a garage built product.. The overall design looks pretty clean..

one point I'd like to make.. The prism people keep pushing this weight thing.. saying how light the unit is, well its all smoke and mirrors..

Steam machines chose to use aluminum cylinders, they are CONSIDERABLY lighter than steel cylinders used in the inspiration.
both units displace about the same amount of water(the prism may actually be more, since the scrubber and cylinders are larger), this means the prism user has to wear much more lead than the Inspiration diver, so in actuality in terms of overall diver weight they are very close.. If an inspiration diver wants with some small mods aluminum cylinders can be used, but then you need more lead..

In fact sometimes(very rarely) I travel with alumimum cylinders to reduce the weight (on my original rig).. This is not my preferred way, I hate wearing a weightbelt.. In the stock config I put 4-6 lbs behing my head in a wetsuit and 6-8 lbs with a dry suit..

I just scaled both CO2 numbers so you could see how facts can really be used for marketing and make things look much different than they are.. here are some numbers

an OLYMPIC athlete can maintain a CO2 production of 1.6 lpm for 5-7 minutes maximum before total exhaustion...

normal easy dives should be in the neighborhod of .9 to 1.0 lpm of co2 production, 1.2-1.3 lpm is moderate work, 1.5 is hard work..

a CCR diver with good technique should be able to figure out his CO2 production rate.. for each liter of oxygen consumed your body produces about .9 liters of CO2...

This is actually one nice point of the Inspiration guages reading Bar not PSI, the inspiration cylinders are 3l fabers (20cft) filled to 200 bar, which means 600 LFG (liters free gas), so a diver using 20 bar of o2 an hour (10 bar per 30 mins) is using 1 liter of oxygen per minute... You cant easily do this in PSI

The rockland aquanauts is trying to put together a rebreather day at its may meeting.. we are trying to get as many different types as possible.. The Board is extending an invitation to a prism instructor also..

The format we will be looking at doing is a general overview (15-30 minutes)of rebreather technolong SCR, CCR oxygen , both advantages and disadvantages, then each instructoror user will talk about their rig.. I will probably do the overview which will be a glossing over of a class I run.. Introduction to CCR (its not a certification class- and is not rebreather specific) but its still a few hours for that class..

 

[scuubaadoo]

please keep me informed if this comes to be. thank you for all the information so far, need to think about this for awhile.

 

[Shas]

Okay there seems some mis-conceptions in how the PRISM is configured and operates so here goes;

one might say what if you flood the battery compartment?? yes both batteries are shot, but if water got this far, so is the loop, and most definately the cells, if this happened on a prism youd be off the loop also since the cells would also be shot...

No, the PRISM has it's single 9v battery (get it at any 7/11 or corner store) in a seperate battery compartment OUTSIDE the breathing loop. You flood the battery compartment - your flying manually, but your still CCR constant PO2.

electronics for the inspiration will read 3 cells simulatenously.. each display has it own power source so its basically the same as one driven by cells.. the inspiration has independent power source, each controller has its own battery.. so one dead battery doesn'y kill the unit...

The PRISM secondary reads all the sensors, it doesn't need a battery to operate. On systems with battery driven backups it is true you have a secondary source, however we have found over the last decade that this causes more problems than it solves as a damaged cable, flooded connector or flooded display renders the sensors useless as they are either been driven by the 6, 12 or 24 v battery supply which completely stuffs them or the Po2 indicated is battey leakage voltage across damaged connector,circuit board or what ever which looks like very high Po2's on the display. So not using a battery means only small mV involved. So access to raw sensor data is achieved even when the unit is heavily damaged or electronics flooded because we can turn the system OFF. Obviously if the canister is swamped its all over anyway but typicaly its the peripherals that get whacked and flooded.

The secondary runs directly off the cells, these are custom high output cells also and must be purchased from steam machines.

Yes they are custom - designed specifically for CCR applications and have sufficent output to drive an analog meter. At a RRP of $75.00 per sensor they are comparable with other available sensors - your not being ripped off.

I have seen major problems on the one unit I saw in use, but I'll reserve judgement until I dive with another diver with one because of the person who had issues isn't the best point of reference..

I'll bet that the person you quote was John Taylor who it appears has issues with everything - not lest of which selling a couple of CCR's multiple times and to multiple people.
His old rig has just finished doing a stack of shark tagging down in LaPaz and the new owner has not had any of the issues he claimed - check out Jeremy's site at http://rebreathers.tripod.com/prism/index.html

The inspiration rates the scrubber at 180 mins @ 1.6lpm co2, the official rated duration for the prism is 4 hours at 1.35 lpm co2, scaleing it to 1.6lpm its only 3 hrs 22 mins.. just slightly longer than an inspiration, it also uses 6lbs of scrubber as opposed to 5.5lbs for the inspiration

Interesting numbers but there is no mention of water temp, gas density, scrubber grain size, depth, RMV etc. etc. The duration you quoted was for the 5.4 lb PRISM scrubber, the 6lb scubber you reference gives 300 minutes or 5 hours under USN test standards - look at the SMI website http://www.steammachines.com/PDFs/TM01-03.pdf

for divers not using helium based mixes the radial scrubber of the prism is a potential downside with regards to WOB (work of breathing), Radial scrubbers theoritically have a higher efficiency rating but one side effect is higher breathing resistance.

Wrong - the work of breathing is considerably less because of the increased cross-sectional area. This is considerably larger on the PRISM than the axial flow scrubber. The velocity is also slower and the PRISM canister is insulated from the water temperature so the duration and the pressure drop are considerably better than an axial flow like the Inspiration. This also affords the ability to condense out most of the water on the sides of the housing long before it gets to the sensors which makes for a drier environment for the sensors to perform.

On the inspiration the automatic oxygen addition is added in the scrubber lid which is forced into the inhale lung to mix before returning to the inhale hose to the dsv. the prism injects the gas before the scrubber..

they both have their advantages, the prism has a slightly longer mixing duration but has the negative effect of adding drier gas into the scrubber (the scrubber needs moisture to work to create carbonic acid which is the first phase of co2 removal).

The inspiration injects after the scrubber, so mixing is shorter (but should still be complete), the down side is that the inspiration might momentarily display a PO2 higher than actual..

You just explained why the PRISM has it's injection before the scrubber - it is no drier as there is 100% relative humidity in the system as we are breathing off it and the cansiter is producing water as a by-product of the CO2 reaction. It is done this way on the PRISM as it was always designed as a deep diving set because helium and oxygen do not mix well, the scrubber prevents slugging and poor mixing which you describe before the sensors monitor what you are breathing.

.. The prism people keep pushing this weight thing.. saying how light the unit is, well its all smoke and mirrors..

Steam machines chose to use aluminum cylinders, they are CONSIDERABLY lighter than steel cylinders used in the inspiration.

both units displace about the same amount of water(the prism may actually be more, since the scrubber and cylinders are larger), this means the prism user has to wear much more lead than the Inspiration diver, so in actuality in terms of overall diver weight they are very close.. If an inspiration diver wants with some small mods aluminum cylinders can be used, but then you need more lead..

No it is not smoke and mirrors - the bottom line is the PRISM with full cylinders, full 6lb scrubber ready to dive is 47lbs and has a considerably longer dive duration and much less work of breathing, these are facts as can be verified by the publicly available test data. In the FL Springs, 8lbs of lead is needed in the counterlungs (4 either side) which makes a total unit weight of 55lbs - still less than the Inspiration on the desk. If you wish to use steel cylinders the PRISM can utilise anything up to 7ltr 300 bar steels without customisation.

I just scaled both CO2 numbers so you could see how facts can really be used for marketing and make things look much different than they are.

Yes you can compare as per the test data mentioned above, as an example water temperature is far more significant a factor in the Inspiration than in the PRISM design and gas velocity is different so whichever way you cut it the PRISM has a longer duration and a lower work of breathing and is a lighter unit.

Just asking a question, why every one here come and talk about any other ccr unit than the inspiration, he get kicked in the ass

We'd like to know the answer to this one too.