The design of the DBT5C means it is extremely economical on drive gas as it uses a return spring and the incoming Oxygen pressure to return the piston back to the top of the stroke, which would otherwise require drive air directed below the piston to provide the lift. With this design, air is only supplied to the top of the piston, thereby providing separation between the air and the Oxygen. The air motor section is linked to the Oxygen piston via a pushrod, through a vented chamber, which provides another level of separation.
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The DBT5C will boost air, oxygen, helium and argon to a maximum pressure of 250 bar. The Oxygen piston/cylinder is identical to the HP stage on the DTB10C electrically driven booster, which is rated to 350 bar and cycles at 350 strokes/min. The DTB5C will cycle at a maximum of 190 strokes/min to 250 bar. Being driven continuously at the maximum speed presents no issues and is recommended as the faster the booster is run, the more the venting of the waste air causes the effect of refrigeration which acts to cool the Oxygen cylinder as the waste air is routed via the cooling collar located around the Oxygen cylinder. A cool transfer is essential as it prolongs the service life of the Oxygen seals.
Using the Booster
The DTB5C booster package comes as a "Turnkey" system ready to use. It will take just a few minutes to assemble. The booster is provided with a back-plate which will either screw to the wall, or Cam-band to a diving cylinder for convenience. Next, fit the 2 x 1.5m gas hoses to booster inlet/outlet. Fit your Oxygen supply cylinder adapter to the inlet hose, and the gauge block to the outlet hose and your target cylinder. All connection types are selectable on the order form (insert order form link). Either fit the Scuba hose or the LP connector to the booster air drive inlet. The air inlet to the booster has a 5 micron filter for added protection. You are now ready to start boosting. The booster has a non-return valve at the inlet and outlet so no other non-return valve is required in the system. Opening the Oxygen supply cylinder slowly is perfectly acceptable during the initial decanting so a needle valve is not required. As it has been established, it is advisable to run the booster continuously at maximum speed, so there is no need to attempt to throttle down the speed using the drive air cylinder valve.
Air motor section
Periodic servicing of the air motor section is limited to the lubrication of the timing shuttle located in the top of the booster (using the A500-LK service lube supplied view video here. The A500-SK O-ring service kit covers all wear seals that require replacement. The manual includes a section of detailed drawings and part numbers to ensure this is an easy process.
Oxygen compression assembly
The Oxygen cylinder is made from high-grade stainless steel, heat-treated for extra hardness. The inlet/outlet non-return valves use stainless steel seats with Ceramic valve balls, which remain spherical considerably longer than stainless steel types, so overall we have a very robust piston cylinder arrangement that is rated to 350 bar. The Oxygen seals are of a composite self-lubricating material, held under spring tension on the piston. This unique design actually expands the seals as they wear which provides a very long service life. To change the seals require two screws to be undone to withdraw the piston and replacing the seal set is very simple procedure. A fully detailed drawing of the seal arrangement is available in the manual.
Apart from a 150mm adjustable spanner, a "3/16" and a "5/32" Hex key is required. We can supply these if you live in a country where these might be difficult to find e.g Egypt.
The DTB5C system - What's in the box?
When ordering your booster system we allow for one inlet adapter referred to as your "Primary Inlet Connector", and one outlet adapter as the "Primary Outlet adapter". Any connector type in use throughout the world can be supplied and selected using the drop down menu. If you require a 2nd inlet/outlet adapter then this is referred to as the "Secondary" adapter as is a charged as an optional extra. Generally, secondary adapters are simply screwed onto your Primary adapter for quick and easy use.
The package is as follows:
1 x DTB5C gas booster
1 x Inlet adapter -typically 232bar Din, UK Bullnose, Euro Bullnose
2 x 1.5m Stainless steel braided hose WP 276 bar
1 x Outlet connector and gauge block, bleed screw with 63mm gauge with rubber boot
1 x 1m Scuba air drive hose with QC connector to booster and 7/16" UNF male to fit the LP port on a Scuba 1st stage
1 x pack of service lubricant (3 years supply)
1 x A4 paper copy manual with CD copy with full parts diagrams
Booster ratio 1:36 Describes the ratio between the size of the air and the Oxygen piston
Boost ratio. Describes what pressure is achieved from the inlet pressure. Be aware that this figure is invariably the mathematical probability and not what is actually achieved in worthwhile and workable conditions. The ratio’s quoted are what the booster actually produces in a valid filling operation.
Oxygen 5:1 Helium 4:1 e.g. 50 bar inlet with Oxygen produces 5 x 50 = 250 bar.
Minimum inlet pressure 20 Bar (290 psi)
Maximum outlet pressure 250 bar (3625 psi)
Drive gas pressure required 6-10 bar Max (87-145 psi)
Performance data is very difficult to compare from one booster to another unless identical gas parameters are used to measure each booster’s performance. If the inlet pressure is high and the target cylinder pressure is low then the flow rate is going to be excellent but does not provide a clear indication of performance. It is during the last phase of the transfer when target cylinder pressures are high and inlet pressure low that we get a clear indication of what the booster can do. To present data that relates to a real life situation we could assume you have completed 2 dives on CCR and your 3ltr cylinder has 100 bar remaining. The O2 supply cylinder is a 50ltr W size (J) with 63 bar which will remain fairly static for the duration of the fill.
3ltr x 232 bar = 696 litres
3 x 100 bar (residual pressure) = 300 litres
696 – 300 = 396 litres to complete fill from 100 bar to 232 bar
Booster average @ 63 bar inlet pressure = 24.5 litres/min
396 /24.5 = 16.1 mins
If we want to get some idea of the amount of air required for this fill we can work on a formula that to transfer 1 litre of Oxygen require approx. 3.6 litres of air. Therefore to transfer 396 litres of Oxygen requires approx. 1425 litres of Air, so a little over half of a 10 litre cylinder. The diameter of the air drive piston is 83mm with a 12mm stroke.
Other relevant data taken from test data 21/10/16 serial no 9468
Air pressure inlet 9 bar
Ambient temperature 19°C
Gas inlet temperature 20°C
Final gas outlet temperature 24°C
Test Receiver temperature at finish 22°C
Big Sam mixing gas for the 2017 World Record Deep by Ahmed Gabr to 332m. The two DTB5C booster pumped all the Open circuit Oxygen and Helium required by the dive attempt team.