Sentinel Upgrades

Barrie Law · 16th April 2008, 12:32

Quote: (Originally Posted by Phil)

Hello Dragan,

The offboard will feed all system i.e. Manual Feed, ADV & BOV for DIL and Manual Feed & Solenoid for the O2 side.

The only issue with BOV is the fact that the Sentinel & Boris use QC4 Swagelok for offboard connection, which acts as a flow restrictor. The BOV is only to be used as a sanity breathe in other words 1-2 breathe before you switch to external bailout. You will have to experience the flow restriction at different depth, it obviously depends on the mix you are using.

On my Boris I am using Swagelok QC6 for the offboard, it has a bigger flow!

Cheers

Hi Phil,

I understood it was the Manual Inject / Gas Switching Block that causes the gas restriction here is the section from page 16 of the manual and it reads;

Bailout / Cylinder Configurations
The following is offered as a guide when configuring the Sentinel for a range of diving conditions. This should be used in conjuction with the recommendations from your diver training agency.

Note: Never use the mouthpies BOV in such a manner as it is only connected to a breathable source via the diluent gas block. The gas flow through the gas block may be insufficient to operate a 2nd stage regulator at depth under certain conditions. The prime 'Sanity Breath' gas source should be the in-board gas cylinder which muct be breathable at depth and be of sufficient volume to allow time to switch to an off-board regulator.

Phil · 16th April 2008, 13:56

Hi Barrie,

You are right the primary restriction will be the gas block.

In my head I was thinking of the issue we have when connecting a 2nd stage via a Swagelok, where by the QC4 is too limiting and we should use QC6.

Anyway on my unit I removed the BOV, I am not a big fan!

See you

Barrie Law · 16th April 2008, 14:59

Quote: (Originally Posted by Phil)

Hi Barrie,

You are right the primary restriction will be the gas block.

In my head I was thinking of the issue we have when connecting a 2nd stage via a Swagelok, where by the QC4 is too limiting and we should use QC6.

Anyway on my unit I removed the BOV, I am not a big fan!

See you

Hi Phil,

Did you find a big difference between the flow rates on the QC4 and the QC6 as I considering fitting one directly to the BOV 2nd stage so it can then be supplied from any cylinder I have including O2.

When you say you are not a big fan is that of BOV's in general or of this one in particular?

Phil · 16th April 2008, 15:35

Quote: (Originally Posted by Barrie Law)

Hi Phil,
Did you find a big difference between the flow rates on the QC4 and the QC6 as I considering fitting one directly to the BOV 2nd stage so it can then be supplied from any cylinder I have including O2.

When you say you are not a big fan is that of BOV's in general or of this one in particular?

Barrie,

The all thing started with the Boris since I wanted the flexibility of using the hose as either for the offboard or for a bailout 2nd stage. The QC4 that CCRB sell for the Boris/Sentinel is
1) coded so you can not cross them DIL to O2 or vice versa, which is a good safety feature. In my case since I wanted to use them to feed a 2nd stage and the coding was an issue. I had to choose to mount the coded DIL or O2 connector on the 2nd stage or have two 2nd stage.
2) Also after looking at Swagelok specs I realised that the way CCRB use the QC4 in terms of gas flow is the wrong way around, after speaking with Swagelok they say the impact would be minimal at 10 bars

So based on the above and also from other divers experience I decided to go for QC6. The drawback with QC6 is that they are bulkier and finding the right fittings can be difficult in order to avoid too many adapters and keeping the connector streamline.

Concerning the BOV it is a general feeling and not just for the Sentinel.

Dragan · 17th April 2008, 06:30

Quote: (Originally Posted by Phil)

Hello Dragan,

The offboard will feed all system i.e. Manual Feed, ADV & BOV for DIL and Manual Feed & Solenoid for the O2 side.

The only issue with BOV is the fact that the Sentinel & Boris use QC4 Swagelok for offboard connection, which acts as a flow restrictor. The BOV is only to be used as a sanity breathe in other words 1-2 breathe before you switch to external bailout. You will have to experience the flow restriction at different depth, it obviously depends on the mix you are using.

On my Boris I am using Swagelok QC6 for the offboard, it has a bigger flow!

Cheers

Thanks!

QC6 is the connector I've been thinking of using as well.

Did you get the QC6 as an option from CCRB, or did you mount it by yourself after delivery? Do you know if it's available as option for Sentinel?

Phil · 17th April 2008, 07:41

CCRB will only sell you coded QC4 as offboard. If you want QC6 you are on your own!

IN468 · 17th April 2008, 09:56

I´m now on the way to order QC6 Fittings in order to be more flexible

like mentioned here

http://www.rebreatherworld.com/ourob...ittings-3.html

Darkwater · 22nd April 2008, 13:11

Hi all, following a long weekend away diving with a mate of mine, he's put me under some pressure to release the report I had written following the first course in the Red Sea. Following his comments I have decided to post it -

Thought I would post my views of the Sentinel following a week of diving on the Red Sea course.
As an overview, I have been diving an Inspiration for the last 10 years, 6 of which I have been carrying out trimix diving. I want to start by saying I think the inspiration is a very good rebreather, robust, simple and extremely reliable. I have over the years put it through some quite tough diving environments and it has never let me down. Due to a big increase in the amount of video work I’m doing I was keen to get a good HUD and a set of back mounted lungs was also very appealing. I attended the uk dive show in October and intended to place an order for a new Vision Inspiration, but I came across the Sentinel and following ½ chat with Kevin placed an order.
Below are my thoughts and comments on the unit following the weeks course:
Layout:
• The case is quite a bit smaller than the prototype unit seen at the show – much neater and looks better. Made from injection moulded plastic rather than Carbon fibre. The case is all black, light weight and hard wearing. Following a week of boat diving, (a lot of kit around and not much space) no damage or marks.
• The mouthpiece and BOV are significantly smaller than the show version. Very neat. The mouthpiece is machined from a single piece with a simple central barrel that can be removed so you can easily clean the four O rings. At the bottom of the mouthpiece is a recess for the BOV. The BOV is simply held in place by a split pin. The unit also comes with a blank plug so you can dive the mouthpiece without the BOV. All the components are ‘dimpled’ such that you cannot put them back together incorrectly. The mouthpiece uses the same mushroom valves as the BORIS, and they are impregnated with titanium and are considered the most reliable on the market.
• The Hoses are quite large diameter and rubber. They are however quite thick, much thicker than the inspiration hoses so I think would be quite difficult to tear. The hoses are fitted with two weights, a clip to retain the BOV hose and two clips for the front and rear HUD. The HUD cable is held in place with simple Velcro tie-raps. The hoses are quite long, but in use they do allow for very good head movement. The hoses push onto the mouthpiece (double oring) and are held in place with plastic split rings, (probably need to keep a few of these spare as they tend to spring out when you are removing them). The hose end that fits into the head is very neat. It simply pushes into the recess in the head and is then held in place with a ¼ turn locking ring. To remove you undo the ring, push in a button and the pull them out. The rebreather is supplied with blanks so as soon as you remove the hoses you can blank off the head to keep it clean etc.
• Harness: The backplate is a minimal design stainless steel backplate made by Kent tooling – very good quality. It is custom made as the top of the plate is angled to take account of the bulge in the case for the counterlung. Due to this bulge it is not possible to fit a normal backplate. In use though this was probably one of the most combatable backplates I have used and I cannot imagine why you would need to change it. The harness is fairly standard strapping with neoprene shoulder straps and stainless buckle – again no real reason to change it, (although it may need a chest strap).
• Wing: The wing is custom made by Dive rite, so it is well constructed and looks tough. The wing is unusual in that the majority of the lift is at the bottom to counteract the buoyancy of the counterlung at the top of the unit. This worked very well and you can get perfect trim in the water in only a few dives. The wing also has two trim weight pockets about half way up. I found with 3kg in each was all I needed (6/5mm suit).
• Counterlung: the counterlung is mounted in the case behind you head / shoulders. It connects onto the head and is held in place with a spring loaded catch. It also has an additional rubber clasp to ensure it cannot come loose. Inside it has an anti collapse ring. The counterlung is quite vulnerable and is easy to damage while working on the head, definitely need to keep a spare.
• Pipework: The O2 pipework is very small diameter is it reduced the chance of high volumes of O2 being added if the solenoid jams open. One of the drills we did was to shut off the O2 supply and then empty the remaining O2 pipework contents into the loop. The PPO2 increased only by 0.1. This also makes it very easy to manually maintain PPO2 as you can finely control the O2 injection. On the side of the unit are two hose connection points for O2 one for the solenoid and one for the manual O2 – they are injected into the head at the same location. On the other side of the head is a connection for ADV and manual injection.
• Head: The top of the head can be disconnected from the main body to replace cells etc. Within the head is the CO2 or scrubber cone, which at its widest part has a triple rubber seal into which the scrubber seals against. Removing the CO2 cone then reveals a simple head assembly. The three cells are retained in a recess by a screwed in plate. The cells use a sealed Jack plug. You cannot access the solenoid. The cells face down to minimise the chance of water on their face.
• Scrubber: The scrubber is very unique. It holds 2.2kg of sof. And consists of a canister with a stainless steel mesh at both ends. The top can be removed by depressing three spring loaded catches. The bottom plate is free to move up and down about 20mm. The canister drops onto a spring loaded scrubber plate which has the temp stick system up through the middle. Once the canister is filled and packed down, you lift the canister body up 20mm (as the base moves) and then repack. The spring loaded base unit with the sliding canister base provides a ‘self packing’ system which can take up to 20mm of slack due to granule movement. Typically we were seeing about 5mm movement following a well packed canister. The canister is loaded by pushing it into the base unit until it locks into position with the springs under tension. You then load the whole base onto the rebreather and turn it ¼ to lock it on. As you turn the base the scrubber assembly disengages from the base and springs up into the head and seals against the triple seal. You can check it is in place by removing a hose and looking inside the unit – you can see the scrubber sitting against the top seal. Typically we were getting 5 hours duration over multiple dives.
• Back-up Handset: The back-up handset is designed to be clipped off and once activated stays on for 15sec. It provides a direct readout from the 3 cells. By pressing the bottom button you can also see the milivolt reading of each cell. The unit has back lighting and an independent battery that changes with the main batteries.
• Main handset: A Neat unit with colour screen. The main screen shows a large readout of PPO2, scrubber temp graphic and also scrubber % remaining. In the top right is the status indicator which is typically a green diver with OK underneath it. Any system changes or alarms are shown in the region. Below this is the deco. Information and PPO2 setting. In auto PPO2 mode it advises you as you descend what PPO2 it will change to and how long to the change. One press on the right button and the deco. Information is changed to a graphic representation of the cylinder contents. A single press on the left button will take you to the gas screen (which is similar to the VR3). You can also change between manual and Auto setpoint and also go into open circuit mode. If you elect open circuit it asks you to confirm over two additional screens and then asks you to confirm the gas being used. The level 3 unit has gas 1 to 4 as Dil and Gas 5 to 8 as bailout. If you have more than one gas in the system it will ask you to confirm you are on it when you reach the specified depth for that gas. Holding both buttons gets you to the system summary screen which shows all the systems with a colour code depending on its status. Further double press gets you to the scrubber temp monitoring screen. Further presses get you into summary screens which show detailed information. Eg: PPO2 of each cell, cylinder pressure, % stack life etc. The DIV screen allows you to change settings and even disable cells that are not correct, etc.
• HUD: The HUD is easy to see even in bright light, (although it needs to be moved further onto the mouthpiece so you can see all LED’s a bracket change is one of the upgrades being undertaken). The HUD in normal mode has a single green led for OK status. If they unit has a minor alarm (ie: you need to address!!) then it flashes the green with a blue LED. If there is a major problem a red led flashes and the HUD vibrates. The last LED is white and indicates Deco. You can ascend on the HUD alone until the white LED stops flashing which indicates you have got to the deco stop. If it flashes fast you are either ascending too fast or have gone past the deco stop – easy to use although difficult to see, (hopefully the new bracket will overcome this).
• Gas blocks: very simple layout. The finger grip can be interchanged so you can swop blocks or keep a single spare. Consists of a spindle with 4 o’rings, spring and bottom. Has manual O2 and Dil with Solenoid and ADV cut off. Easy to use and get to, (with either hand). You can also plug in offboard gas through the block. Due to the pipework diameter however you cannot use the BOV to access offboard gas through the gas block. The unit does however have a neat manifold block for the dil side in the back of the unit that an offboard gas wip could be connected to which would enable BOV use.
• Battery: Built in lithium rechargeable batteries, two for the main handset (one as back-up) and an independent battery for the back-up unit. All the early units are fitted with the expedition battery packs which last ages, (easily a week of intense diving). We also had a play with a solar powered charger they intend to launch later in the year.
• Over pressure valve: is located at the bottom of the unit, took a few dives to set it right but once set you just leave it alone. Between dives, if you press it in any water inside will drain out – gives you an indication if you have had a leak etc. The way the base is made water naturally drains down into the unit and if need you could flush out during a dive by flushing with Dil.
OK, this is much longer than I first planned – if you are still reading this I’ll get to the diving:
Dive 1 – hated it!!, Dive 3 – in love!!!
The first dive I found quite odd, the work of breathing is so low that it just did not feel right. The hose was not configured well and was very uncomfortable throughout the dive.

By dive 3 I had played around with the hose angle coming out of the top of the unit, moved the counter weights down and adjusted the hoses around the mouthpiece. With these changes it was very comfortable even with the BOV. I will probably add another 2 weights towards the back to help with this further.
I also found early on that the maintenance of PPO2 is effortless to the point you are not sure its working. As your confidence gains in the unit it is extremely easy to dive. The primary screen gives you a clear status and PPO2 at a single glance and with a few button presses you can get to all the detail you need, even Dil PPO2 at current depth to aid with Dil flush.
The trim in the water is amazing. I have spent 10 years trying to get it right with the Insp. By dive 3 it was nearly there on this unit.
The auto dump takes a bit of getting used to, but again after a couple of dives its effortless, even on an open circuit bailout ascent the unit vented itself without any major buoyancy changes.
It is very much like diving open circuit but without the work of breathing. It is comfortable in all positions, (except on your back) and it was not affected by head down decent. Manual control of the unit is also very simple and with the fine adjustments you could make it was very easy to get into a pattern with the O2 addition. The loop volume is easy to keep to a minimum and the adv not too sensitive.

Cheers

***diverklondike*** · 22nd April 2008, 13:41

excellent post.. have some green..

***caveseeker7*** · 22nd April 2008, 14:10

Thanks so much for the detailed post!

16th April 2008, 12:32	#31 (permalink)
Barrie Law RebreatherWorld Sponsor Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Jun 2005 Location: Ireland Posts: 726	Re: Sentinel Upgrades Quote: (Originally Posted by Phil) Hello Dragan, The offboard will feed all system i.e. Manual Feed, ADV & BOV for DIL and Manual Feed & Solenoid for the O2 side. The only issue with BOV is the fact that the Sentinel & Boris use QC4 Swagelok for offboard connection, which acts as a flow restrictor. The BOV is only to be used as a sanity breathe in other words 1-2 breathe before you switch to external bailout. You will have to experience the flow restriction at different depth, it obviously depends on the mix you are using. On my Boris I am using Swagelok QC6 for the offboard, it has a bigger flow! Cheers Hi Phil, I understood it was the Manual Inject / Gas Switching Block that causes the gas restriction here is the section from page 16 of the manual and it reads; Bailout / Cylinder Configurations The following is offered as a guide when configuring the Sentinel for a range of diving conditions. This should be used in conjuction with the recommendations from your diver training agency. Note: Never use the mouthpies BOV in such a manner as it is only connected to a breathable source via the diluent gas block. The gas flow through the gas block may be insufficient to operate a 2nd stage regulator at depth under certain conditions. The prime 'Sanity Breath' gas source should be the in-board gas cylinder which muct be breathable at depth and be of sufficient volume to allow time to switch to an off-board regulator. __________________ Barrie Law Rebreather World Store Supplying the Rebreather World Tel:US +19548403892 Fax:US+19543333792 Tel:EU+442071930496 Fax:EU+442077606344 Mobile+353876880628 Skype:barrielaw Email: barrie@rebreatherworldstore.com
(Offline)

16th April 2008, 13:56	#32 (permalink)
Phil Custom Title Allowed! Current Rebreather/s: Megalodon Ouroboros rEvo Other CCR Other Rebreather/s: Inspiration Classic Inspiration Vision Evolution Megalodon rEvo Other CCR Join Date: May 2005 Location: Geneva-Switzerland Posts: 170	Re: Sentinel Upgrades Hi Barrie, You are right the primary restriction will be the gas block. In my head I was thinking of the issue we have when connecting a 2nd stage via a Swagelok, where by the QC4 is too limiting and we should use QC6. Anyway on my unit I removed the BOV, I am not a big fan! See you __________________ Phil __________________ CCR/OC Instructor CCR Training to Mixed Gas in Switzerland, France, UK & Germany on Megalodon/KISS/Ouroboros/rEvo/Inspiration/Evolution/Sentinel www.zerogravitydiving.com
(Offline)

16th April 2008, 14:59	#33 (permalink)
Barrie Law RebreatherWorld Sponsor Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Jun 2005 Location: Ireland Posts: 726	Re: Sentinel Upgrades Quote: (Originally Posted by Phil) Hi Barrie, You are right the primary restriction will be the gas block. In my head I was thinking of the issue we have when connecting a 2nd stage via a Swagelok, where by the QC4 is too limiting and we should use QC6. Anyway on my unit I removed the BOV, I am not a big fan! See you Hi Phil, Did you find a big difference between the flow rates on the QC4 and the QC6 as I considering fitting one directly to the BOV 2nd stage so it can then be supplied from any cylinder I have including O2. When you say you are not a big fan is that of BOV's in general or of this one in particular? __________________ Barrie Law Rebreather World Store Supplying the Rebreather World Tel:US +19548403892 Fax:US+19543333792 Tel:EU+442071930496 Fax:EU+442077606344 Mobile+353876880628 Skype:barrielaw Email: barrie@rebreatherworldstore.com
(Offline)

16th April 2008, 15:35	#34 (permalink)
Phil Custom Title Allowed! Current Rebreather/s: Megalodon Ouroboros rEvo Other CCR Other Rebreather/s: Inspiration Classic Inspiration Vision Evolution Megalodon rEvo Other CCR Join Date: May 2005 Location: Geneva-Switzerland Posts: 170	Re: Sentinel Upgrades Quote: (Originally Posted by Barrie Law) Hi Phil, Did you find a big difference between the flow rates on the QC4 and the QC6 as I considering fitting one directly to the BOV 2nd stage so it can then be supplied from any cylinder I have including O2. When you say you are not a big fan is that of BOV's in general or of this one in particular? Barrie, The all thing started with the Boris since I wanted the flexibility of using the hose as either for the offboard or for a bailout 2nd stage. The QC4 that CCRB sell for the Boris/Sentinel is 1) coded so you can not cross them DIL to O2 or vice versa, which is a good safety feature. In my case since I wanted to use them to feed a 2nd stage and the coding was an issue. I had to choose to mount the coded DIL or O2 connector on the 2nd stage or have two 2nd stage. 2) Also after looking at Swagelok specs I realised that the way CCRB use the QC4 in terms of gas flow is the wrong way around, after speaking with Swagelok they say the impact would be minimal at 10 bars So based on the above and also from other divers experience I decided to go for QC6. The drawback with QC6 is that they are bulkier and finding the right fittings can be difficult in order to avoid too many adapters and keeping the connector streamline. Concerning the BOV it is a general feeling and not just for the Sentinel. __________________ Phil __________________ CCR/OC Instructor CCR Training to Mixed Gas in Switzerland, France, UK & Germany on Megalodon/KISS/Ouroboros/rEvo/Inspiration/Evolution/Sentinel www.zerogravitydiving.com
(Offline)

17th April 2008, 06:30	#35 (permalink)
Dragan New Member Current Rebreather/s: Other CCR Other Rebreather/s: Other CCR Join Date: Feb 2008 Location: Vasteras, Sweden Posts: 11	Re: Sentinel Upgrades Quote: (Originally Posted by Phil) Hello Dragan, The offboard will feed all system i.e. Manual Feed, ADV & BOV for DIL and Manual Feed & Solenoid for the O2 side. The only issue with BOV is the fact that the Sentinel & Boris use QC4 Swagelok for offboard connection, which acts as a flow restrictor. The BOV is only to be used as a sanity breathe in other words 1-2 breathe before you switch to external bailout. You will have to experience the flow restriction at different depth, it obviously depends on the mix you are using. On my Boris I am using Swagelok QC6 for the offboard, it has a bigger flow! Cheers Thanks! QC6 is the connector I've been thinking of using as well. Did you get the QC6 as an option from CCRB, or did you mount it by yourself after delivery? Do you know if it's available as option for Sentinel? __________________ "It is what we think we know already that often prevents us from learning." Claude Bernard {1813-1878, French Physiologist}
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17th April 2008, 07:41	#36 (permalink)
Phil Custom Title Allowed! Current Rebreather/s: Megalodon Ouroboros rEvo Other CCR Other Rebreather/s: Inspiration Classic Inspiration Vision Evolution Megalodon rEvo Other CCR Join Date: May 2005 Location: Geneva-Switzerland Posts: 170	Re: Sentinel Upgrades CCRB will only sell you coded QC4 as offboard. If you want QC6 you are on your own! __________________ Phil __________________ CCR/OC Instructor CCR Training to Mixed Gas in Switzerland, France, UK & Germany on Megalodon/KISS/Ouroboros/rEvo/Inspiration/Evolution/Sentinel www.zerogravitydiving.com
(Offline)

17th April 2008, 09:56	#37 (permalink)
IN468 "master of desaster" Current Rebreather/s: Ouroboros Other Rebreather/s: Inspiration Classic Join Date: Feb 2006 Location: Germany Posts: 136	Re: Sentinel Upgrades I´m now on the way to order QC6 Fittings in order to be more flexible like mentioned here http://www.rebreatherworld.com/ourob...ittings-3.html
(Offline)

22nd April 2008, 13:11	#38 (permalink)
Darkwater New Member Current Rebreather/s: Other CCR Other Rebreather/s: Inspiration Classic Other CCR Join Date: Mar 2008 Location: Australia Posts: 7	Re: Sentinel Upgrades Hi all, following a long weekend away diving with a mate of mine, he's put me under some pressure to release the report I had written following the first course in the Red Sea. Following his comments I have decided to post it - Thought I would post my views of the Sentinel following a week of diving on the Red Sea course. As an overview, I have been diving an Inspiration for the last 10 years, 6 of which I have been carrying out trimix diving. I want to start by saying I think the inspiration is a very good rebreather, robust, simple and extremely reliable. I have over the years put it through some quite tough diving environments and it has never let me down. Due to a big increase in the amount of video work I’m doing I was keen to get a good HUD and a set of back mounted lungs was also very appealing. I attended the uk dive show in October and intended to place an order for a new Vision Inspiration, but I came across the Sentinel and following ½ chat with Kevin placed an order. Below are my thoughts and comments on the unit following the weeks course: Layout: • The case is quite a bit smaller than the prototype unit seen at the show – much neater and looks better. Made from injection moulded plastic rather than Carbon fibre. The case is all black, light weight and hard wearing. Following a week of boat diving, (a lot of kit around and not much space) no damage or marks. • The mouthpiece and BOV are significantly smaller than the show version. Very neat. The mouthpiece is machined from a single piece with a simple central barrel that can be removed so you can easily clean the four O rings. At the bottom of the mouthpiece is a recess for the BOV. The BOV is simply held in place by a split pin. The unit also comes with a blank plug so you can dive the mouthpiece without the BOV. All the components are ‘dimpled’ such that you cannot put them back together incorrectly. The mouthpiece uses the same mushroom valves as the BORIS, and they are impregnated with titanium and are considered the most reliable on the market. • The Hoses are quite large diameter and rubber. They are however quite thick, much thicker than the inspiration hoses so I think would be quite difficult to tear. The hoses are fitted with two weights, a clip to retain the BOV hose and two clips for the front and rear HUD. The HUD cable is held in place with simple Velcro tie-raps. The hoses are quite long, but in use they do allow for very good head movement. The hoses push onto the mouthpiece (double oring) and are held in place with plastic split rings, (probably need to keep a few of these spare as they tend to spring out when you are removing them). The hose end that fits into the head is very neat. It simply pushes into the recess in the head and is then held in place with a ¼ turn locking ring. To remove you undo the ring, push in a button and the pull them out. The rebreather is supplied with blanks so as soon as you remove the hoses you can blank off the head to keep it clean etc. • Harness: The backplate is a minimal design stainless steel backplate made by Kent tooling – very good quality. It is custom made as the top of the plate is angled to take account of the bulge in the case for the counterlung. Due to this bulge it is not possible to fit a normal backplate. In use though this was probably one of the most combatable backplates I have used and I cannot imagine why you would need to change it. The harness is fairly standard strapping with neoprene shoulder straps and stainless buckle – again no real reason to change it, (although it may need a chest strap). • Wing: The wing is custom made by Dive rite, so it is well constructed and looks tough. The wing is unusual in that the majority of the lift is at the bottom to counteract the buoyancy of the counterlung at the top of the unit. This worked very well and you can get perfect trim in the water in only a few dives. The wing also has two trim weight pockets about half way up. I found with 3kg in each was all I needed (6/5mm suit). • Counterlung: the counterlung is mounted in the case behind you head / shoulders. It connects onto the head and is held in place with a spring loaded catch. It also has an additional rubber clasp to ensure it cannot come loose. Inside it has an anti collapse ring. The counterlung is quite vulnerable and is easy to damage while working on the head, definitely need to keep a spare. • Pipework: The O2 pipework is very small diameter is it reduced the chance of high volumes of O2 being added if the solenoid jams open. One of the drills we did was to shut off the O2 supply and then empty the remaining O2 pipework contents into the loop. The PPO2 increased only by 0.1. This also makes it very easy to manually maintain PPO2 as you can finely control the O2 injection. On the side of the unit are two hose connection points for O2 one for the solenoid and one for the manual O2 – they are injected into the head at the same location. On the other side of the head is a connection for ADV and manual injection. • Head: The top of the head can be disconnected from the main body to replace cells etc. Within the head is the CO2 or scrubber cone, which at its widest part has a triple rubber seal into which the scrubber seals against. Removing the CO2 cone then reveals a simple head assembly. The three cells are retained in a recess by a screwed in plate. The cells use a sealed Jack plug. You cannot access the solenoid. The cells face down to minimise the chance of water on their face. • Scrubber: The scrubber is very unique. It holds 2.2kg of sof. And consists of a canister with a stainless steel mesh at both ends. The top can be removed by depressing three spring loaded catches. The bottom plate is free to move up and down about 20mm. The canister drops onto a spring loaded scrubber plate which has the temp stick system up through the middle. Once the canister is filled and packed down, you lift the canister body up 20mm (as the base moves) and then repack. The spring loaded base unit with the sliding canister base provides a ‘self packing’ system which can take up to 20mm of slack due to granule movement. Typically we were seeing about 5mm movement following a well packed canister. The canister is loaded by pushing it into the base unit until it locks into position with the springs under tension. You then load the whole base onto the rebreather and turn it ¼ to lock it on. As you turn the base the scrubber assembly disengages from the base and springs up into the head and seals against the triple seal. You can check it is in place by removing a hose and looking inside the unit – you can see the scrubber sitting against the top seal. Typically we were getting 5 hours duration over multiple dives. • Back-up Handset: The back-up handset is designed to be clipped off and once activated stays on for 15sec. It provides a direct readout from the 3 cells. By pressing the bottom button you can also see the milivolt reading of each cell. The unit has back lighting and an independent battery that changes with the main batteries. • Main handset: A Neat unit with colour screen. The main screen shows a large readout of PPO2, scrubber temp graphic and also scrubber % remaining. In the top right is the status indicator which is typically a green diver with OK underneath it. Any system changes or alarms are shown in the region. Below this is the deco. Information and PPO2 setting. In auto PPO2 mode it advises you as you descend what PPO2 it will change to and how long to the change. One press on the right button and the deco. Information is changed to a graphic representation of the cylinder contents. A single press on the left button will take you to the gas screen (which is similar to the VR3). You can also change between manual and Auto setpoint and also go into open circuit mode. If you elect open circuit it asks you to confirm over two additional screens and then asks you to confirm the gas being used. The level 3 unit has gas 1 to 4 as Dil and Gas 5 to 8 as bailout. If you have more than one gas in the system it will ask you to confirm you are on it when you reach the specified depth for that gas. Holding both buttons gets you to the system summary screen which shows all the systems with a colour code depending on its status. Further double press gets you to the scrubber temp monitoring screen. Further presses get you into summary screens which show detailed information. Eg: PPO2 of each cell, cylinder pressure, % stack life etc. The DIV screen allows you to change settings and even disable cells that are not correct, etc. • HUD: The HUD is easy to see even in bright light, (although it needs to be moved further onto the mouthpiece so you can see all LED’s a bracket change is one of the upgrades being undertaken). The HUD in normal mode has a single green led for OK status. If they unit has a minor alarm (ie: you need to address!!) then it flashes the green with a blue LED. If there is a major problem a red led flashes and the HUD vibrates. The last LED is white and indicates Deco. You can ascend on the HUD alone until the white LED stops flashing which indicates you have got to the deco stop. If it flashes fast you are either ascending too fast or have gone past the deco stop – easy to use although difficult to see, (hopefully the new bracket will overcome this). • Gas blocks: very simple layout. The finger grip can be interchanged so you can swop blocks or keep a single spare. Consists of a spindle with 4 o’rings, spring and bottom. Has manual O2 and Dil with Solenoid and ADV cut off. Easy to use and get to, (with either hand). You can also plug in offboard gas through the block. Due to the pipework diameter however you cannot use the BOV to access offboard gas through the gas block. The unit does however have a neat manifold block for the dil side in the back of the unit that an offboard gas wip could be connected to which would enable BOV use. • Battery: Built in lithium rechargeable batteries, two for the main handset (one as back-up) and an independent battery for the back-up unit. All the early units are fitted with the expedition battery packs which last ages, (easily a week of intense diving). We also had a play with a solar powered charger they intend to launch later in the year. • Over pressure valve: is located at the bottom of the unit, took a few dives to set it right but once set you just leave it alone. Between dives, if you press it in any water inside will drain out – gives you an indication if you have had a leak etc. The way the base is made water naturally drains down into the unit and if need you could flush out during a dive by flushing with Dil. OK, this is much longer than I first planned – if you are still reading this I’ll get to the diving: Dive 1 – hated it!!, Dive 3 – in love!!! The first dive I found quite odd, the work of breathing is so low that it just did not feel right. The hose was not configured well and was very uncomfortable throughout the dive. By dive 3 I had played around with the hose angle coming out of the top of the unit, moved the counter weights down and adjusted the hoses around the mouthpiece. With these changes it was very comfortable even with the BOV. I will probably add another 2 weights towards the back to help with this further. I also found early on that the maintenance of PPO2 is effortless to the point you are not sure its working. As your confidence gains in the unit it is extremely easy to dive. The primary screen gives you a clear status and PPO2 at a single glance and with a few button presses you can get to all the detail you need, even Dil PPO2 at current depth to aid with Dil flush. The trim in the water is amazing. I have spent 10 years trying to get it right with the Insp. By dive 3 it was nearly there on this unit. The auto dump takes a bit of getting used to, but again after a couple of dives its effortless, even on an open circuit bailout ascent the unit vented itself without any major buoyancy changes. It is very much like diving open circuit but without the work of breathing. It is comfortable in all positions, (except on your back) and it was not affected by head down decent. Manual control of the unit is also very simple and with the fine adjustments you could make it was very easy to get into a pattern with the O2 addition. The loop volume is easy to keep to a minimum and the adv not too sensitive. Cheers
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22nd April 2008, 13:41	#39 (permalink)
*diverklondike* Moderator Current Rebreather/s: Inspiration Classic Other CCR Other Rebreather/s: Inspiration Classic Other CCR Join Date: Oct 2005 Location: Delaware, USA Posts: 1,463	Re: Sentinel Upgrades excellent post.. have some green..
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22nd April 2008, 14:10	#40 (permalink)
*caveseeker7* Who loves ya, baby Current Rebreather/s: Sport Kiss Other Rebreather/s: Prism Topaz Join Date: Jan 2005 Location: Too far from Neverland Posts: 5,326	Re: Sentinel Upgrades Thanks so much for the detailed post! __________________ Cheers Stefan "It is still a good day if you are on the green side of the grass! Su amigo Roberto!" Sponsor Lou in Race For Life!
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