Blending and Transfill

22 Items

Set Descending Direction
  1. DGX Gas Transfill Hose with Analog Gauge
    DGX Gas Transfill Hose with Analog Gauge
    $145.00
  2. Deluxe Gas Blending and Transfill Kit
    DGX Gears Deluxe Gas Blending and Transfill Kit with Digital Gauge
    $609.00
  3. Gas Boosters *
    Gas Boosters *
     
  4. In the Storage Case
    Divesoft HE/O2 Analyzer - Blender Pro Set
    $1,269.00
  5. Accurate Cylinder Pressure Checker
    Accurate Cylinder Pressure Checker
    $48.00
  6. Front View
    DGX Digital Cylinder Pressure Checker
    $199.00
  7. DIN-to-CGA870 Fill Adapter
    DGX Gears Adapter: DIN to CGA-870 Pin Index YOKE
    $129.00
  8. Oxygen Pin Fitting
    DGX Gears Adapter: DIN to CGA-870 Pin Index POST
    $79.00
  9. Front View
    DGX Premium Yoke-to-DIN Fill Adapter
    $30.00
  10. Divesoft Tank Silencer
    Divesoft Tank Silencer
    $49.00
  11. DGX HP Sealing DIN Plug w/Pressure Release
    DGX HP Sealing DIN Plug w/Pressure Release
    $20.00
  12. Black and Silver DGX DIN-to-Yoke Spin-on Adapters
    DIN-to-Yoke Spin-on Adapter
    $25.00
  13. DIN Connector
    DGX Adapter: 1/4 NPT Female to DIN SCUBA Connector w/Bleed
    $30.00
  14. Bulk Gas Storage Cylinder Valve Adapters
    Bulk Gas Storage Cylinder Valve Adapters with QD Stem
    $79.00
  15. Quick Disconnect = 1/4-inch NPT
    Quick Disconnect = 1/4-inch NPT
    $29.00
  16. SCUBA DIN Adapter with QD Stem
    SCUBA DIN Male with QD Stem
    $79.00
  17. SCUBA DIN Female with QD Female
    SCUBA DIN Female with QD Female
    $129.00
  18. NPT to Scuba Adapters *
    NPT to Scuba Adapters *
    $0.00
  19. PTFE Seal Tape - Oxygen Service
    PTFE Seal Tape - Oxygen Service
  20. DGX Digital Gauge 5000 PSI
    DGX Digital Gauge 5000 PSI
    $159.00
  21. TDI Nitrox Gas Blender
    TDI Nitrox Gas Blender
    $35.00
  22. TDI Advanced Gas Blending
    TDI Advanced Gas Blending
    $35.00
Tek Tip Warning Image WARNING

You must meticulously follow the recommendations of the US Department of Transportation (DOT), Compressed Gas Association (CGA), and other federal/state/local agencies, plus your training agency for equipment maintenance, handling, storage, labeling, filling, transport and use of compressed gases. Ultimately, you must make the final decision to assume all risks associated with the use of any compressed gases.

Z Factors for SCUBA

Cylinder volume is defined by the internal dimensions of the tank, and normally measured in cubic inches or liters of water. Free capacity is defined by the amount of breathing gas released at the surface that the scuba tank will hold at its maximum rated service pressure. Determining the true free capacity from the water volume is troublesome because not everybody does their math quite the same way when converting water volume to free capacity. In fact, many tanks actually hold as much as 10% LESS air than the size commonly used to describe them and up to 20% LESS for gases other than air.

The easiest method to determine the true gas capacity of SCUBA cylinders is to use the Compressibility Factor (Z). To calculate true capacity, divide the ideal capacity by the Z Factor obtained from the table below. See our article Calculating SCUBA Cylinder Capacity for more information on how to make these easy calculations. This table is arranged so that interpolation is possible for most pressures and mixtures. Just because this table lists Z Factors at higher pressures doesn't mean you can or should fill tanks to that pressure, especially with pure oxygen.

Gas Mixture
Common Name
2015 psig
70°F
2640 psig
70°F
3000 psig
70°F
3442 psig
70°F
3600 psig
70°F
207 bar_g
15°C
232 bar_g
15°C
300 bar_g
15°C
Nitrox 50
(deco)
≈ 0.9773 ≈ 0.9897 ≈ 1.0007 ≈ 1.0178 ≈ 1.0248 ≈ 0.9938 ≈ 1.0077 ≈ 1.0575
Nitrox 32 ≈ 0.9912 ≈ 1.0080 ≈ 1.0214 ≈ 1.0412 ≈ 1.0491 ≈ 1.0153 ≈ 1.0316 ≈ 1.0868
air (dry) ≈ 0.9984 ≈ 1.0173 ≈ 1.0320 ≈ 1.0532 ≈ 1.0615 ≈ 1.0263 ≈ 1.0438 ≈ 1.1020
Trimix 21/35
(normoxic)
≈ 1.0636 ≈ 1.0901 ≈ 1.1066 ≈ 1.1280 ≈ 1.1359 ≈ 1.1065 ≈ 1.1243 ≈ 1.1764
Trimix 18/45 ≈ 1.0736 ≈ 1.1010 ≈ 1.1176 ≈ 1.1389 ≈ 1.1467 ≈ 1.1185 ≈ 1.1362 ≈ 1.1869
Trimix 10/50
(aka Heliair)
≈ 1.0784 ≈ 1.1064 ≈ 1.1233 ≈ 1.1446 ≈ 1.1524 ≈ 1.1246 ≈ 1.1423 ≈ 1.1927
Trimix 15/55 ≈ 1.0798 ≈ 1.1075 ≈ 1.1241 ≈ 1.1449 ≈ 1.1524 ≈ 1.1256 ≈ 1.1429 ≈ 1.1918
Trimix 10/70
(hypoxic)
≈ 1.0833 ≈ 1.1104 ≈ 1.1262 ≈ 1.1458 ≈ 1.1529 ≈ 1.1284 ≈ 1.1448 ≈ 1.1902
oxygen
(pure)
≈ 0.9387 ≈ 0.9383 ≈ 0.9424 ≈ 0.9515 ≈ 0.9558 ≈ 0.9328 ≈ 0.9400 ≈ 0.9738
helium
(pure)
≈ 1.0668 ≈ 1.0869 ≈ 1.0985 ≈ 1.1125 ≈ 1.1175 ≈ 1.1008 ≈ 1.1126 ≈ 1.1445

† This Z Factors table was prepared using the NIST REFPROP database and software, version 10. For calculation purposes, the gases were defined to be pseudo-pure air (dry), Nitrox mixtures (O2, balance N2) and Trimix (O2, Helium, balance N2) mixtures composed of the stated percentages on a molar basis and all without the trace gases or contaminates typically found in the breathing gases used for SCUBA. That means these perfect gas Z Factors would be a little different for the stuff in your tank, but not enough to be significant.