ABOUT DIVE HOSES
Our Advice: Rubber hoses with lengths tailored for their application (see also Standard Hose Lengths in Gear Guide for Regulators). Metal and glass SPG (60mm | 2.36in for primary, 50mm | 1.97in for secondary).
HOSE MATERIALS
Rubber with internal braiding
Why choose rubber hoses? They have been around the longest and offer high reliability with a simple design. Used for both high pressure and low pressure applications, most are compatible with high oxygen applications. Rubber hoses are generally identified by having a matt rubber coating and are easily “squishable” by hand when not pressurised.
Composite with external braiding
Why choose braided nylon hoses? Flexi-braid style hoses are light-weight and remain flexible when pressurised. Used for both high pressure and low pressure applications, some offer higher burst or working pressure ratings. Identifiable by their external polymer braiding.
Braided hoses were briefly fashionable before it became apparent that they tended to fray with use, becoming abrasive and damaging to skin and equipment (nicknamed the “little black cactus” or “black toothbrush”). When wrapped around the back of a diver’s neck they are particularly damaging to skin and drysuit seals.
Due to their flexibility under pressure composite hoses with external braiding (eg Miflex) are still the best choice for CCR hose routing and recreational second stage regulators. Their lighter weight is attractive for all levels of divers for travelling.
Kevlar reinforced high pressure (HP)
DUPONT branded high pressure hoses feature a double weave of Kevlar braiding to replace the canvas braiding in the rubber hoses, with a smooth polymer coating on the outside. They are thin and flexible like the external braided hoses, with amazing burst pressures (13,400bar | 194350psi). With a smooth outer layer they do not become abrasive as with braided hoses. However, they are more expensive than rubber hoses.
HOSE TYPES
High-pressure (HP) hoses
What are HP hoses? HP hoses are used to join the high-pressure port of the first stage regulator to the Submersible Pressure Gauge (SPG). They bear the full pressure of the scuba cylinder (up to 300bar | 4350psi).
The female end has a smooth walled chamber for a “swivel spigot” to connect an SPG and allow it to swivel 360 degrees when pressurised. The male end has a pin-sized aperture to limit gas flow in a burst hose scenario.
HP hoses can be identified by the larger 11.1125mm | 7/16in diameter male end (compared to a LP hose at 9.5250mm | 3/8in), or from the high-pressure markings printed on the hose. The male end will have a within
Low-pressure inflator (LPI) hoses
What are low pressure inflator hoses? LPI hoses connect to the intermediate pressure (7-11bar | 100-160psi) ports of the first stage regulator and supply gas to utilities such as Buoyancy Compensator Device (BCD) power inflators, dry suit inflators, Surface Marker Buoys (SMBs) or anything else that does not need a high flow rate of gas.
LPI hoses generally have a working rating of at about twice that of the intended intermediate pressure (20-30bar | 290-435psi). LPI hoses rely on a Schrader Valve within a retractable protective sleeve/collar to connect to a male Quick Disconnect (QD) fitting on the utility.
Low-pressure (LP) regulator (LPR) hoses
What are low pressure regulator hoses? LPR hoses connect to the intermediate pressure (7-11bar | 100-160psi) ports of the first stage regulator and supply gas to the second stage regulator. They are designed for higher flow rates than LPI hoses and so rarely have quick disconnect features. They can be identified from a 9.5250mm | 3/8in) diameter male connector and a 14.2875mm 9/16in female fitting with smooth chamber. The female fitting takes an o-ring protected valve spindle located on the input side of the second stage regulator, and allows the second stage regulator to swivel when pressurised.
HOSE LENGTHS
|
Recreational |
Twinset |
Stage/Deco or
Standard
Sidemount |
Alternative
Sidemount |
| High Pressure |
|
|
|
|
115cm | 6 in
(0.5ft) |
|
|
SPG |
SPG |
56cm | 22in
(1.8ft) |
|
SPG (small diver
body size) |
|
|
61cm | 24in
(2ft) |
SPG |
SPG |
|
|
90-100cm | 35-
39in (2.9-
3.25ft)* |
|
|
|
|
Low Pressure
Regulator |
|
|
|
|
50cm | 19.5in
(1.6ft) |
Primary
Regulator (small
diver body size) |
Secondary
regulators with
directed ports
(port faces
direction of
second stage) |
|
|
61cm | 24in
(2ft) |
Primary
Regulator |
Secondary
Regulator |
|
|
104cm | 41in
(3.4ft) |
Secondary
Regulator |
|
Primary
Regulator |
Secondary
Regulator |
210cm | 82in
(7ft) aka "long
hose" |
|
Primary
Regulator |
|
Primary
Regulator |
Low Pressure
Inflator |
|
|
|
|
37cm | 14.5in
(1.2ft) |
|
|
Drysuit Inflator
Backup Gas
Supply* |
Drysuit Inflator
Backup Gas
Supply* |
56cm | 22in
(1.8ft) |
BCD/Wing
Inflator
Drysuit Inflator |
Wing Inflator
Drysuit Inflator |
Wing Inflator
Drysuit Inflator |
Wing Inflator
Drysuit Inflator |
75scm | 29.5in
(2.5ft) |
Drysuit Inflator |
Drysuit Inflator |
|
|
* CCR and specialised applications
SUBMERSIBLE PRESSURE GAUGE (SPG)
Submersible Pressure Gauges (SPG) are used to tell the contents of the diver’s tanks. Mechanical SPGs use Bourdon tubes sensitive to very small pressure changes. The tubes contain oil and end with a diaphragm that the air pressure pushes against. Digital models use transducers that convert air pressure into electrical signals that send the information to pressure readings on the small screen.
SPGs are most accurate in the central range of the gauge graduations and divers should avoid breathing their tanks below 50 bar | 725 psi because the low pressure reading may be inaccurate by as much as 40%.
Most SPGs, regardless of their branding, are manufactured by Termo Industria in Italy. Your SPG should have a metal body with a glass face. Standard sizes are:
- Primary SPG 60mm | 2.36in diameter, and
- Secondary SPG (stage/deco cylinders) 50mm | 1.97in diameter.
Plastic SPGs are cheap and nasty, and not durable enough to rely upon.
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