Scuba diving hoses are often the most mistreated part of the dive gear setup. They are frequently allowed to fray, chafe or rot, or are needlessly bent, twisted and stretched out of shape.
Sharp bends, kinks and tight loops in scuba hoses can weaken or damage the hose. Unusual bending and distortion can weaken the integrity of the inner braiding. Don't hang a regulator by the first stage in such a manner as to allow the hoses to bend.
Anytime scuba diving hoses develop pin hole leaks, they should be replaced immeadiately. This is a sign that air is leaking through the lamination of the hose, and it will gradually become worse. So replace it as soon as you spot this.
Typically your scuba diving hoses are attached to your regulators, instruments and/or drysuit. Thus you should also consider following our advise on Regulator Care when cleaning your dive hoses.
As with all diving equipment, rubber and double-braided polyester diving hoses require regular checks and maintenance. Your diving hoses should be cleaned down after each dive to ensure they remain in good condition.
First: Slide any hose protectors away from hose fittings. Use a scrub brush and water to remove any gross contamination from the hoses and fittings. Rinse thoroughly with fresh water, preferably warm (but not hot) water.
Second: Spray a liberal coat of the cleaning solution until all surfaces are wet. A mild liquid detergent, or selected commercial cleaning agents, can be used.
Third: Let stand for 10 minutes. If solution appears to be drying, apply more solution to keep it wet for the full 10 minutes.
Fourth: After 10 minutes, rinse the hoses in a container of clean fresh water, or rinse under running clean water.
Fifth: Wipe the scuba hoses as dry as possible. Lay the dive hoses out flat to dry in a shaded, well-ventilated location with the first stage positioned higher than the second stages and gauge console. Let the hoses dry completely before sliding any hose protectors back into place.
Sixth: Store the regulators with the hoses in a natural curl so they are not kinked and there is no weight on the hose connections to the first stage. They are then ready to provide you with a trouble-free dive the next time out.
Descale your hoses and fittings to reduce the build-up of lime scale. This should be carried out with a de-scaling agent based on citric acid. As with all brass fittings, over a period of time a small build up of scale is possible and care should be taken to carefully remove this to prevent damage or restriction to the use of the hose.
A descaler based on phosphoric acid should not be used as this would cause damage to the outer layers of the hose.
As with all dive equipment, regular inspections for damage, wear and tear, are required. Although Miflex and other double braided polyester hoses are more abrasion resistant and longer lasting than traditional rubber hoses, this does not mean that they cannot or will not wear — and as such should be inspected regularly.
Our tips for inspection are:
If you have hose protectors on your scuba hoses, you need to pull them back from the fittings so that you can clean and inspect the hoses and fittings properly. Please consider permanently removing all hose protectors.
The 'hose protectors' on the ends of scuba hoses next to the first and second stages provide a cosmetic appearance, however there is no evidence they prevent hose damage. Hoses sometimes fail where the fitting is swaged onto the hose, but that's caused by gas pressure, and a hose protector is not going to prevent that from happening.
Because hose protectors interfere with routing and streamlining, they are almost never seen on regs used in technical diving. In fact, hose protectors may compromise safety and many experienced divers don't use or recommend them.
Hose protectors hold water against the fitting, causing corrosion and hiding developing problems. The post dive care and maintenance recommendation is to pull the hose protectors back from the fittings, rinse and inspect. However, our observation is that not only do most divers not perform this suggested maintenance, when they do they are actually pulling hard at the most failure prone part of the hose.
Our maintenance recommendation: Permanently remove all hose protectors. We use a special hook blade cutting tool to do this, but you could carefully use a pair of side cutters rather than pull them off. Replace the hose if there is evidence of excessive wear or damage.
First Stage Hose Leak: If a leak is detected where the regulator, inflator or high pressure hose fitting attaches to the first stage regulator, this can be just a loose fitting, and can be solved by tightening the fitting. If the fitting is tight and the leak persists, remove the regulator from the scuba cylinder. Next, remove the fitting from the first stage, remove the O-ring and install a new O-ring of the correct size. Reinstall the hose and check for leaks again. If the leak still persists, have the regulator serviced by a competent scuba technician.
Second Stage Hose Leak: If a leak is detected where the regulator hose fitting is attached to a second stage regulator, do not attempt to tighten this fitting unless you have the proper tools and knowledge to do so. This is a job best left for a competent scuba technician, since damage to the second stage valve can result in some regulators if done incorrectly.
BCD/Inflator/Jacket Hose Leak: If air leaks around the quick disconnect fitting on the BCD/Inflator/Jacket hose when attached to the power inflator or drysuit inflator, this may be caused by a damaged O-ring or Schraider valve. Replace the O-ring with the proper sized O-ring, and/or replace the Schraider valve using the proper tool. For many, this is a job best left for a competent scuba technician.
SPG/Transmitter Hose Leak: If a leak is detected where the high pressure hose connects to your submersible pressure gauge (SPG) or dive computer air pressure transmitter, this may be caused by a loose fitting, or a faulty high pressure swivel-pin air-spool. First, try tightening the fitting. If the fitting is tight and the leak persists, remove the hose from the SPG or transmitter and either replace the air spool O-rings, or the entire airspool. For many, this is a job best left for a competent scuba technician.
The Scuba Doctor has a Miflex Hoses Service Box available which can be used by a competent person to fix these hose leaks.
Whenever working with scuba hoses and fittings, always use the proper tools and proper size wrenches. This will prevent galling or scratching from the wrench. When removing or installing hoses onto the first stage regulator, support the first stage lightly in a soft-jawed vice to hold it securely.
Regulator manufacturers use different sized screw threads when connecting all of the hoses to their first stages so that nobody can accidentally attach a low pressure hose to a high pressure port and damage their regulators. Before installing a hose in the first stage, make sure it is the correct hose (either high or low pressure) and install it only in its correct port in the regulator (often labelled "HP" or "LP" accordingly). As many regulator parts are made out of marine grade brass, which is quite a soft metal, attempting to screw two different threads together can damage the threads and be very expensive to fix, or in most cases replace.
When installing a hose properly, it should go all the way to the O-ring by hand easily, and then be tightened with a wrench the rest of the way. If there is any resistance at all, the threads should be checked immediately. Hoses and blanking plugs only need to be screwed in with 5 Nm of Torque, which is just over hand tight. Too much force and you can strip the threads.
We always recommend that for reasons of safety, that all hoses are only changed and fitted by a competent person and would suggest that this is done for you at your local dive store and/or diving service centre.
We offer this suggestion and recommendation, as we only wish for you to gain maximum benefit from your dive hoses and sometimes the fitting of hoses requires specific tools and torque levels to prevent potential and unnecessary damage to your equipment.
All hoses with O-ring seals only have a torque requirement of circa 5 Nm and please be aware that over tightening could potentially cause damage to your equipment and hose fittings.
Safety is important, and at The Scuba Doctor we take this seriously and offer the following guideance:
At no time should you consider cutting your scuba hose and reconnecting any type of fitting to the hose, or to try and reconnect the hose fittings, as this will reduce all safety in your hose.
Recommendation: In our experience double-braided polyester hoses are more reliable than rubber but keep in mind that all scuba hoses, both rubber or polyester, will fail sooner or later either due to age, storage conditions or handling. Prior to every dive trip you should always pressurise and inspect your hoses for mechanical damage, corroded fittings, bulges and leaks. We suggest replacing all scuba hoses every five years or 500 dives, whichever comes first.