Not Fuel-proof!

[skippydiesel]

3 minutes ago, onetrack said:

There's enough reason alone just in that poor design, to not use these Hengst inline plastic filters on an aircraft. What VH aircraft uses fuel piping connections that are not barbed? None, I'll wager. It's an accident waiting to happen.

 

Barbed fuel line connections are standard throughout the automotive industry to prevent fires. Even the cheap Ryco plastic inline filters have barbed tails. 

Maaaate  your grasping at ephemeral straws - if you have to rely on the "barbs" for security, your installation is suspect. Properly sized, cut to length and supported fuel hose/filter will not give you any problems (guaranteed). Remember the Hengst  type filters are used in a multitude of diesel (vibration) applications and have been since about the mid 1960's, if not erlier - millions & millions of hours without issue.

 

As for "Barbed fuel line connections are standard throughout the automotive industry to prevent fires" -  incorrect on both accounts.

The "barb" is almost exclusively found on the cheap plastic mower type filters you are promoting & not found on the more "professional" filters.

I would suggest they are there to "impress" the naive, more of a marketing gimmick than a practical requirement.

Perhaps they have an application where people want to use them for varying hose ID - not what I would see as good practice.

Barbs have the potential to damage the inside/lining of the hose, particularly when you are removing the filter for inspection/replacement. When installing the new/cleaned filter, you run the risk of liberating small bits of hose which will ending up in carb jets.

Further - the barbs require considerable stretching of the hose, this may cause a permanent hose deformation, which could impact negatively on sealing the next time a barb is introduced.

As for fires?? where did this unsupported statement come from?? Please justify.

[onetrack]

Maaate, the difference between a diesel application and a petrol application, is the fire potential from a diesel leak is only a miniscule level of the fire potential of a petrol leak.

 

My reference is Number 7 on the webpage below ...

 

https://firesafety.tips/guide-to-car-fire-prevention-and-control/

 

Good quality fuel piping that utilises barbed tails doesn't possess sharp-edged barbs that can cut hose. You will find the vast majority of fuel line fittings have barbed tails, the smooth pipe fittings are in the small minority.

[skippydiesel]

 

21 minutes ago, onetrack said:

Maaate, the difference between a diesel application and a petrol application, is the fire potential from a diesel leak is only a miniscule level of the fire potential of a petrol leak.

 

My reference is Number 7 on the webpage below ...

 

https://firesafety.tips/guide-to-car-fire-prevention-and-control/

 

Good quality fuel piping that utilises barbed tails doesn't possess sharp-edged barbs that can cut hose. You will find the vast majority of fuel line fittings have barbed tails, the smooth pipe fittings are in the small minority.

 Automotive fires are predominantly electrical in origin (diesel/petrol/LPG/eclectic) Always has been .

 

Agricultural machinery fires add, bearing/bush failures and flammable dust.

 

Fuel is rarely the primary cause.

 

The suggestion that any leaking fuel (diesel/petrol/LPG) is somehow less of concern, because the fuel has a lower flash point, is ludicrous . 

 

A cursory glance at your reference leaves me somewhat unimpressed  - does not come across as a factual, pragmatic, authoritative,  document - more of light weight reading from a magazine article.

 

In my experience your last statement  is incorrect - almost all factory fittings, where push on hose is used, utilise smooth (metal/plastic) pipe, sometimes with single ring/bulge to assist mechanical (clip) retention. After market stuff tends toward the barb fitting - a marketing ploy to visually entice/reassure the naive.

 

I would go so far as to state - where the hose is correctly matched to the spigot/pipe,  the barb is an unnecessary and even unhelpful hang over from a by gone era, when hose quality was not as consistent as it is today (if you go to the trouble to purchase quality hose). 

 

 

 

[kgwilson]

Aircraft Spruce sell various plastic polymer coated paper element plastic filters which are 30 microns or less and are barbed. All of the brass fuel line fittings, shutoff valves, fuel selector valves and facet fuel pumps I bought from Aircraft Spruce have barbed inlets and outlets. All designed for use in petrol delivery systems, not diesel. Diesel filters probably need 50 microns mesh size or more to allow adequate flow due to the higher viscosity of diesel & consequently let more dirt through however this would not be enough to cause blockages to even the smallest jets.

[RFguy]

I wouldnt use anythign that wasnt barbed or olive crimped. 

[skippydiesel]

27 minutes ago, kgwilson said:

Aircraft Spruce sell various plastic polymer coated paper element plastic filters which are 30 microns or less and are barbed. All of the brass fuel line fittings, shutoff valves, fuel selector valves and facet fuel pumps I bought from Aircraft Spruce have barbed inlets and outlets. All designed for use in petrol delivery systems, not diesel. Diesel filters probably need 50 microns mesh size or more to allow adequate flow due to the higher viscosity of diesel & consequently let more dirt through however this would not be enough to cause blockages to even the smallest jets.

Yeah! well both the aircraft industry and the Yanks (who dominate) are conservative to a stultifying level.

True erring on the side of caution is a good thing in aviation but sometimes this caution is just  a cover for tradition & stubbornness, in the face of of strong evidence in support of a better alternative.

[skippydiesel]

28 minutes ago, RFguy said:

I wouldnt use anythign that wasnt barbed or olive crimped. 

Its a sort of free world - go for it!

 

Constructive reasoning rather than bald statements are a tad more persuasive.

Edited June 3, 2021 by skippydiesel

[skippydiesel]

Just to assist you doubting Thomas's - Below are  typical modern push on/hose applications,  (note the non barbed spigots):

The after market customer expects to purchase a "barbed" spigot - so that's what the supplier gives him - to do otherwise would require "expensive" (lost sales) education. Manufactures on the other hand have found a better way and overwhelmingly have moved to non barbed spigots.

 

[kgwilson]

Push lock fitting are great for use with water and low pressure hydraulics with inflexible hoses. Higher pressure push lock fittings usually are barbed. The 6mm push fittings for the thermoplastic hose that goes from my water filter to the fridge are a genius design, strong & never leak but can be removed with ease any time.

Edited June 3, 2021 by kgwilson

[skippydiesel]

58 minutes ago, kgwilson said:

Push lock fitting are great for use with water and low pressure hydraulics with inflexible hoses. Higher pressure push lock fittings usually are barbed. The 6mm push fittings for the thermoplastic hose that goes from my water filter to the fridge are a genius design, strong & never leak but can be removed with ease any time.

Googled "push lock" -turns out  I have used this system on plastic (potable) house water supply systems - great, very quick, bit costly and I would expect to be heavy in an aircraft application - not sure how this relates to barb or no barb hose push connections.

 

Back on track - I had forgotten -  my Rotax oil hoses,  are all no barb push fittings. What say the naysayers to that?

[Old Koreelah]

8 hours ago, skippydiesel said:

...There has been a long standing recommendation that gauze filter medium, uncased in a clear body (for easy visual inspection) are the standard.

The gauze filters, I use, were about $6 each (I did purchase  about 20 to get the best price) but what price would you put on your life?

Can you suggest a brand name and seller?

[Thruster88]

1 hour ago, skippydiesel said:

Googled "push lock" -turns out  I have used this system on plastic (potable) house water supply systems - great, very quick, bit costly and I would expect to be heavy in an aircraft application - not sure how this relates to barb or no barb hose push connections.

 

Back on track - I had forgotten -  my Rotax oil hoses,  are all no barb push fittings. What say the naysayers to that?

The rotax 912 oil system's that I have seen have these fittings, they definitely have barbs. You could get away with no barbs because all external oil lines on a rotax 912 have no pressure in them, suction or atmospheric pressure only.

[skippydiesel]

56 minutes ago, Old Koreelah said:

Can you suggest a brand name and seller?

My favorite are the Hengst brand and the two filter I use are H102 WK & H103WK (there are others) and I am fairly sure I purchased mine (way back) from Tooley Imports https://www.tooleyimports.com.au/

[skippydiesel]

1 minute ago, Thruster88 said:

The rotax 912 oil system's that I have seen have these fittings, they definitely have barbs. You could get away with no barbs because all external oil lines on a rotax 912 have no pressure in them, suction or atmospheric pressure only.

Man! I mentioned the raised collar, on some non barb, push fittings way back in this conversation and I complete dispute that this feature can be called a "barb" - a barb being a sharp edged devise designed to make removal, without damage, impossible.

 

Further the "barb" style of fitting requires multi small points of contact to make a seal. This is why so many people apply damaging pressure, using a hose clamp, to ensure a seal. 

 

The smooth pipe relies on the correct size of hose being in contact with a much much larger surface area. In this situation the seal  has been achieved and the clamp, lightly tightened, provides security/ hose from slipping. 

 

How do you figure the oil lines have no pressure? If this were the case the oil would not circulate. The oil lines are subject to both negative (suction) and positive (return) pressures.

 

The point is not the pressure per say but the ability of the (low pressure) system to resit leaking (air in/oil out) and the hopefully reasoned choice you might make between the traditional multi sharp(ish) ring style and newer smooth pipe, often  fitted with a smooth ring/swelling, to do the job.

 

I agree that these fittings are designed for low pressure (not nil) as is the case for the fuel lines under discussion. High pressure lines require a very different engineering approach.

 

Check out the photos I provided above - other than size they are all similar to the Rotax fittings in your schematic.

[walrus]

“Push on ‘’ fittings require push on hose - which is much stronger than ordinary hose circumferentially. Do not mix hose types and fittings.

[skippydiesel]

On 04/06/2021 at 8:01 PM, walrus said:

“Push on ‘’ fittings require push on hose - which is much stronger than ordinary hose circumferentially. Do not mix hose types and fittings.

You might like to be a little more precise in your commentary.

 

Push on is not the same as push lock - all low pressure hose systems that are pushed on, to whatever spigot design, are push on.

 

Push lock requires a different hose (stiffer plastic like construction) & sophisticated "joiner" system and in my limited experience (domestic water supply) have no application in fuel systems, that I am aware of . Also push lock are designed to be a one use application - that is they are either impossible or very difficult to reuse. Where push on are usually reusable, at least a few times.

[walrus]

Skip, yes you are correct - push lock. Example linked below. This stuff in my experience requires tools and a great deal of strength to fit. I use them on my Rotax oil lines.

 

‘’The Rotax inlet line is under light negative pressure on starting when cold and the return has no more than 6 psi.

 

https://speedflow.com.au/hose-ends/400-series/

 

 

 

[skippydiesel]

3 hours ago, walrus said:

Skip, yes you are correct - push lock. Example linked below. This stuff in my experience requires tools and a great deal of strength to fit. I use them on my Rotax oil lines.

 

‘’The Rotax inlet line is under light negative pressure on starting when cold and the return has no more than 6 psi.

 

https://speedflow.com.au/hose-ends/400-series/

 

 

 

Wow! I checked out the web site  you provided - they are selling Gates Barricade EFI hose for over X2 the price that I got mine from Repco