Snuba air line filters?

[happy-diver]

Because that's scuba

 

[happy-diver]

Hey Waterwulf I love you man!

Ignorance isn't not knowing something! It's not wanting to know!

 

[happy-diver]

 

[iain/hsm]

Oh stop it already. You’re just PO’d because someone questioned your expertise by calling you out on a stupid statement.

Don’t use a filter because it may get plugged up and restrict the flow.

Well duh! lol That’s what a filter is supposed to do. That’s why you’re supposed to change them on a regular basis. Just own it and move on.

Your confused I never actually said that … Your inventing it in your mind.

Your making things up to feed your declining delusion but that is understandable at your age.
Look I feel sorry for you what with your various medical conditions, your previous heart attack and subsequent medical procedures. The stent you had fitted after your heart attack and your head trauma. Bluntly put your just a weak old man with sad delusions but that doesn’t excuse the delusional statement you made above.

Swiss psychiatrist Elisabeth Kübler-Ross wrote the accepted standard in the five broad stages of death. Denial and anger are the first two with many additional sub texts frustration rage confusion being some of those additions. In this you are progressing well and are at these points already.

Further I do understand your need to “carry on as normal” to prove others wrong and I would suggest your implied interest in Hookah diving is based on your declining health and mobility issues.

The example being your inability to carry a scuba cylinder coupled with the medical advise given to you to limit your depth to no more than 30 FSW This is good advise given to you by a medical professional.

Your age, your self declared medical conditions and your doctors advise would suggest a change of plan. Give up this Hookah/Snuba quest of yours to other younger fitter folk and live out what days you are left on the porch in contemplation of what next.

As far as the engineering details given earlier in the post these are only needed to make an informed choice on the types and styles of filter and my suggestion to you for a non return valve. To others the internet buy now and Ebay are sufficient with simplistic coloured brochures. But to be honest with you maybe better to leave these finer details for other younger fitter folk to discuss. I think you're done.

 

[Still Kicking]

No message

 

[iain/hsm]

I think to conclude in outline and avoid any future confusion on the general question of umbilical filters for this specific Hookah question we are talking specifically about:

1. In-line fitted at the diver end of a submersible umbilical prior to a demand valve (2nd stage regulator).
2. Down hose at the diver end for shallow water 2 bar ATA recreational use.
3. Specifically using at the surface a standard Scuba 1st stage regulator possibly with a modified spring for interstage pressure considerations but with a scuba HP Cylinder topside.

So to be clear: Fitting an inline filter to an umbilical when using a scuba cylinder supply from the surface and a possibly spring modified second stage demand valve for shallow 30 FSW use

We are NOT discussing topside filtration or for an LP electric compressor or a petrol/gas powered engine.

In addition the reason for my detailed list of design criteria earlier in the thread on a suitable filter would have been clear to illustrate the engineering risks of each specific filter element choice. But no matter.

Now just one single additional point to illustrate complexity using surface fed scuba cylinder topside that come into play.

1. The demand valve (2nd Stage) itself needs additional consideration as to the inhalation and exhalation effort required to operate within any required performance standard.

The combination of inhalation together with exhalation effort combined effects is what is known as the work of breathing and users should be aware of two additional consequences of fitting any filter in line.

1. The reduction in breathing performance and increase in the work of breathing by fitting in line down hose filter in the first place.

2. The difference in performance between fitting an inline filter topside against fitting it inline at the diver end all of which are in addition to the detrimental performance of fitting an inline filter in the first place.

This one aspect illustrated above details the experience care and attention needed and to show that sometimes careful consideration is a deeper subject than you at first think.

 

[Tanks A Lot]

Putting aside whatever else Iain may have said, his advice on this point is worth listening to. Placing a filter just before the second stage is a bad idea for several reasons:

• The second stage relies on a stable intermediate pressure to function properly. Even in standard SCUBA setups, maintaining this stability is already a challenge. It's one of the main drivers behind many of the engineering decisions in first-stage design. In a Hookah system, this challenge is amplified by the very long hose, which introduces a delay in pressure compensation from the first stage. A filter will compound this delay.
• Adding a filter into this setup will inevitably restrict gas flow, even when the filter is perfectly clean. This restriction not only affects the second stage but also underlines why, in all SCUBA gear, filters are placed before the first stage. Any drop in gas flow translates into undesirable pressure fluctuations at the second stage, making its job more difficult.
• Yes, a filter will catch particulates, as it's designed to do, as you rightly point out. But when placed on the low-pressure side, any clogging will have a much more noticeable impact on performance than it would on the high-pressure side. Gas flow is affected much more quickly and dramatically.
• You also mention the risk of inner hose linings separating. This is a non-issue if you're using hoses from reputable manufacturers, which are easy to source. The only widespread case of hose liner degradation in the SCUBA industry occurred before 2015, when some manufacturers had the brilliant idea of using Polyester-urethane (AU) instead of the more suitable Polyether-urethane (EU). AU, doesn’t play nicely with humidity (brilliant choice for dive gear!) so it started to crystallize and fail.
• If a hose does degrade and release particulates of any medical significance, those particles will clog a filter so quickly that the filter becomes useless almost immediately. I have not heard or read of any hose shedding any meaningful amount of particulate, beside the earlier mentioned incident.

In my view, there are really only two likely outcomes:

1. The filter does nothing, because the air is clean to begin with.
2. The filter is overwhelmed quickly if there’s any meaningful contamination.

How the debris gets into the breathing loop and past the first stage & compressor filter is something that is beyond me, leaving aside the quite frankly absurd notion of hose disintegration. Even ignoring all of the above, I still question the usefulness of a filter just before the second stage. Air from a properly functioning compressor and a well-maintained cylinder is of such high quality that even the filter on the first stage is arguably redundant.

I would strongly suggest you do not add a filter anywhere in the low-pressure side of the system. It is useless at best and outright dangerous at worst.