Conshelf XIV HP hose

[John C. Ratliff]

Lain,

I am a diver since 1959, and have accumulated many, many very old single hose regulators. Almost all of these hoses are still serviceable (although I have taken a few HP gauge hoses, and one or two LP hoses, off-line). But I also a man a retired professional safety person, who worked in the occupational health and safety field for over 35 years. I am curious as to when and why the hose standards changed? I assume it is these newer hoses, made to the EN 250 standard, are the source of the five year recommendation. Why is this standard now being used?

SeaRat

 

[Bryan@Vintage Double Hose]

In hindsight chopping up all these US made rubber hoses that were more than 12 months old might have been a mistake?
I guess I better send a follow up email to my vendor and apologize for calling their products "black rubber whips of death"

 

[iain/hsm]

Lain,

I am a diver since 1959, and have accumulated many, many very old single hose regulators. Almost all of these hoses are still serviceable (although I have taken a few HP gauge hoses, and one or two LP hoses, off-line). But I also a man a retired professional safety person, who worked in the occupational health and safety field for over 35 years. I am curious as to when and why the hose standards changed? I assume it is these newer hoses, made to the EN 250 standard, are the source of the five year recommendation. Why is this standard now being used?

SeaRat

John

I have attempted to make the original reply pan global, but for detail EN250 is a legal requirement for regulator design and performance in Europe only.

Now it is a great shame that USA didn’t have a similar sports standard. But for sports regulators what came to be known as DEMA 105 and this document became known as the accepted norm in the USA. A bunch of non engineers DEMA members made up the standard DEMA 105 with the performance aspect of the regulator based mainly on the US Navy regulator performance trials and reports yet DEMA 105 also did not include any detailed technical design or required hose performance.

Basically like EN 250 it was breathing performance trail only with WOB work of breathing, inhalation effort over exhalation effort) under controlled minimum water temperatures over a minimum BPM breath per minute cycle rate at varing depth. The kicker as far as safety is concerned is when you read the standards in detail the requirement for both HP and LP intermediate hose it’s hopelessly ineffective and child like in it’s ineffective minimum safety requirements and inadequate of any performance requirement or minimum material specifications, or testing or life expectancy.

In both sports scuba standards both EU and USA it is just a couple of lines with the sole requirement in the standard to do a pull test of the end fittings while bent under pressure hanging a weight over a 2 inch tube. The net result being that any and all junk hose from any old part of the world can claim to meet these inadequate poor standards.

Further it allowed this light weight “exposed” outer cover toilet water type hose to become popular with its lightweight flexibility nonsense at the expense of longevity age elongation deflection. Further the use of poor cheap lighter polymers with the known short (5 year) design life was pushed under the Safety Of banner (SOB) in requiring servicing every year including replacing the hose. Yada Yada. In a word its a cash cow at the sports divers expense, the industry were warned yet took no notice, ship of fools I guess.

Now if you look back at your 35 years diving you will find that the industrial hose standard for most if not all of that time was built around that of SAE 100 R3 this was the standard of norm back then and provided the engineer with the basic tool of performace and testing with which to make an informed design. For the spcific application of diving the engineer would have specified the inner tube component correctly for diving applications gas etc and the mandril manufacturing the hose details of allowable lubricants in its production. This was the agreed accepted and safe method of manufacture.

Sadly today in this post you can find only one supplier still standing suppling good quality hose and and he get’s dragged in the flack for the poor performing imported new junk. Go figure. And the reason why this type of discussion is sidelined to the backwaters of old men and vintage gear topic on the forum.

What is it they say? “Beware of an old man in a profession, where men usually die young” .

 

[Bryan@Vintage Double Hose]

Sadly today in this post you can find only one supplier still standing suppling good quality hose and and he get’s dragged in the flack for the poor performing imported new junk. Go figure. And the reason why this type of discussion is sidelined to the backwaters of old men and vintage gear topic on the forum.

What is it they say? “Beware of an old man in a profession, where men usually die young” .

Thank you

 

[iain/hsm]

In hindsight chopping up all these US made rubber hoses that were more than 12 months old might have been a mistake?
I guess I better send a follow up email to my vendor and apologize for calling their products "black rubber whips of death"

You have and supply a fine product based on a well known tried and tested design code of SAE 100 R. The problem is as was anticipated that eventually poor design poor material and poor manufacture products from others in the far east etc flooding the sports scuba market with cheap copies is killing the quality market.

I don’t often say this (As a Scot) but buying hose with Made in USA down the side is a safer option in a world of scuba junk than just a DOM ident. (date of manufacture)

By example Miflex on the other hand saw the opportunity to capitalize on the allowable poor design code under the EN250 standard and launched the lightweight coloured toilet water supply hose.
Subsequently as the polymer breakdown became public knowledge thanks in part to diver forums
and the subsequent product recalls became evident, the sports diving industry has gone all out to make the hose an annual service replacement item, wait and watch.

Out of interest here is the first time Miflex went public with the lightweight hose 17th January 2008
Also included for interest are my comments (iain/hsm) back then to Miflex.
My doesn’t time fly when your having fun.

Hello from Miflex Hoses

And again in 2015 when the failures started to make themselves known and what I feel was the first
time I made reference (post #30) about the short life expectancy of using PET granules
with some interesting references. Most of which are still available.


Medium Pressure hose degradation - Page 3

Hope it helps. Iain/hsm

 

[ams511]

A very interesting thread. I have a question though. Looking at low pressure rubber hoses only, are there different construction methods? The reason I ask is some rubber hoses appear to be far more flexible that others. For example I have a 90s vintage Sherwood Maximus where the hose is very flexible. Much more so than my other regulators of the same period.

 

[captain]

I think I will hold on to my 30 and 40 year old hoses.

 

[tbone1004]

A very interesting thread. I have a question though. Looking at low pressure rubber hoses only, are there different construction methods? The reason I ask is some rubber hoses appear to be far more flexible that others. For example I have a 90s vintage Sherwood Maximus where the hose is very flexible. Much more so than my other regulators of the same period.

many different kinds of low pressure hoses in rubber and finding good ones is increasingly difficult...

 

[John C. Ratliff]

Here is some more specific information from K here isn't some more specific information from DAN and other sources from an internet search I just made.

Divers Alert Network South Africa - Newsflash! Low Pressure Hose Deterioration

Nylon-Braided Regulator Hose Diving Emergency

From the Consumer Product Safety Commission:
XS Scuba Recalls Miflex High Pressure Diving Hoses Due to Drowning Hazard

This is a different recall:
Suunto Recalls Air Hoses Used With Scuba Gear

Well, I have don a bit more research, and found that this grade is made of polyethylene terephthalate. The articles above show how the interior can degrade into crystals. I wanted to go further, and see chemically what may be happening.

To know why I am interested, you should know that befor retiring I was an industrial hygienist, and have evaluated numerous chemical hazards in the workplaces I was responsible for.

Whenever there is a chemical degradation, there will be byproducts produced. I want to understand what these are, and whether there is a potential for exposure to the diver? So I did some digging.

Wikipedia is a good place to start, b cause while not a definitive text, it usually contains a lot of good information. One interesting little detail I found out is that one early brand name for polyethylene terephthalate is Dacron. If you were my age, you would recognize the name, Dacron.
Polyethylene terephthalate - Wikipedia

From the description in Wiki, one of the possible degradation products is acetaldehyde (CAS number 75-07-0).

PET is subjected to various types of degradations during processing. The main degradations that can occur are hydrolytic, and probably most important, thermal oxidation. When PET degrades, several things happen: discoloration, chain scissionsresulting in reduced molecular weight, formation of acetaldehyde, and cross-links ("gel" or "fish-eye" formation). Discoloration is due to the formation of various chromophoric systems following prolonged thermal treatment at elevated temperatures. This becomes a problem when the optical requirements of the polymer are very high, such as in packaging applications. The thermal and thermooxidative degradation results in poor processibility characteristics and performance of the material.

The American Conference of Governmental Industrial Hygienists (ACGIH), in their 2014 TLVs and BEIs booklet, lists the Threshold Limit Value for acetaldehyde as a Short-term Exposure Limit (STEL--15 minute limit) which is a Ceiling Limit of 25 parts per million (no more than 25 ppm). There was no 8-hour TLV for this chemical.

Acetaldehyde is also listed with a A2 notification. According to the ACGIH, acetaldehyde is Lisa ed as: '"A2--Suspected Human Carcinogen: Human data are accepted as adequate in quality but are conflicting or insufficient to classify the agent as a confirmed human carcinogen; OR the agent carcinogenic in experimental animals at dose(s), or by roue(s) of exposure, at site(s), or histologicalmtype(S), or by mechanism(s) concider d relevant to worker exposure. The A2 is used primarily when there is limited evidence of carcinogenicity in humans and sufficient evidence of carcinogenicity in experimental animals with relevance to humans."

My question now is whether there has been any data on the potential for acetaldehyde in the air of these deteriorated hoses?

SeaRat
John C. Ratliff, CSP, CIH(2006-2017), MSPH