Air Hose: 3/8" vs 1/2"
- Thread starter SubLGT
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The one with the largest ID which means less pressure drop over the 25 ft length. Would also depend on what's on the working end of the hose. If you have for example an air nozzle, then the nozzle is going to be the main restriction and the flow would probably be about the same with both hoses. But if the working end isn't the main restriction then the bigger ID will be better -ie, an air tool that needs good air flow then the 1/2" ID is the way to go.
The answer is so obvious, making the question pointless.
Won't the 1/4 npt fitting be the limiting factor on both hoses?
Originally Posted By: SubLGT
Which of these air hoses has the best air flow (cfm), assuming a supply pressure of 90psi ?
HOSE A: 25ft x 3/8" i.d. , with male 1/4-NPT fitting on both ends.
HOSE B: 25ft x 1/2" i.d. , with male 1/4-NPT fitting on both ends.
You did not specify the CFM requirements of your tool. For a 3/4" impact and larger go with 1/2".
Also some coupler fittings are pretty bad with respect to air resistance.
If you go with 1/2" hose, go with 1/2" fittings.
Which of these air hoses has the best air flow (cfm), assuming a supply pressure of 90psi ?
HOSE A: 25ft x 3/8" i.d. , with male 1/4-NPT fitting on both ends.
HOSE B: 25ft x 1/2" i.d. , with male 1/4-NPT fitting on both ends.
You did not specify the CFM requirements of your tool. For a 3/4" impact and larger go with 1/2".
Also some coupler fittings are pretty bad with respect to air resistance.
If you go with 1/2" hose, go with 1/2" fittings.
Originally Posted By: spasm3
Won't the 1/4 npt fitting be the limiting factor on both hoses?
no, since air compresses a little restriction at the ends has an effect but the whole hose being smaller has an effect too.
The best scenario is a bigger hose with bigger or at least high flow fittings
for example a milton High V vs a regular
Its kind of the same effect you get from an electrical extension cord
you have to keep going up in conductor size for length of the cord.
ie 14gauge is ok at 50ft for 12amps but you need 12gauge at 100ft.
To get adequate airflow you have to keep increasing the size of the hose for the run length.
of course this is with air tools that use alot of air.
And dont be confused by "average air use" sometimes they figure you are only using it 25% of the time. so it will say 4cfm but it really needs 16cfm for continuous use.
Hopefully that is not too confusing.
Won't the 1/4 npt fitting be the limiting factor on both hoses?
no, since air compresses a little restriction at the ends has an effect but the whole hose being smaller has an effect too.
The best scenario is a bigger hose with bigger or at least high flow fittings
for example a milton High V vs a regular
Its kind of the same effect you get from an electrical extension cord
you have to keep going up in conductor size for length of the cord.
ie 14gauge is ok at 50ft for 12amps but you need 12gauge at 100ft.
To get adequate airflow you have to keep increasing the size of the hose for the run length.
of course this is with air tools that use alot of air.
And dont be confused by "average air use" sometimes they figure you are only using it 25% of the time. so it will say 4cfm but it really needs 16cfm for continuous use.
Hopefully that is not too confusing.
Originally Posted By: spasm3
Won't the 1/4 npt fitting be the limiting factor on both hoses?
Bingo
and then you have many folks running Type M fittings, so either would work fine ...
Won't the 1/4 npt fitting be the limiting factor on both hoses?
Bingo
and then you have many folks running Type M fittings, so either would work fine ...
Originally Posted By: Rand
Hose C 1/2" ID with high flow fittings.
I agree, but I don't want to change the outlet 1/4" quick disconnect (Milton M style) on the compressor to a different type, or change the 5/16" piping on the regulator to 1/2", just for my 3/4" HF impact wrench that will only see rare use. So I will use a 1/2 inch hose with the 1/4" fittings.
Hose C 1/2" ID with high flow fittings.
I agree, but I don't want to change the outlet 1/4" quick disconnect (Milton M style) on the compressor to a different type, or change the 5/16" piping on the regulator to 1/2", just for my 3/4" HF impact wrench that will only see rare use. So I will use a 1/2 inch hose with the 1/4" fittings.
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The 3/8 with Euro 7.2 (Milton V works with 7.2) 1/4" thread fittings will handle about 20 CFM with a 50 ft hose with approx a 4 psi pressure drop from what I can tell with my spray equipment.
It is the ideal size for most automotive garage and spray gun uses with the exception of 3/4 and 1" impact guns. Schlepping a 1/2" hose around when spraying is a PITA.
Edit: Check the spec on the HF gun I doubt its more than 20 CFM. I just looked its only 9 cfm@ 90 psi well withing 3/8 hose. The fittings are going to make the difference.
It is the ideal size for most automotive garage and spray gun uses with the exception of 3/4 and 1" impact guns. Schlepping a 1/2" hose around when spraying is a PITA.
Edit: Check the spec on the HF gun I doubt its more than 20 CFM. I just looked its only 9 cfm@ 90 psi well withing 3/8 hose. The fittings are going to make the difference.
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yep I just looked at the 3/4 earthquake and its 9 cfm. The Milton V fittings with make all the difference in the world. It will work better than 1/2 hose with the more restrictive fittings.
If I install a Milton V coupler on the compressor regulator output, will I be able to attach my older tools and hoses that have Milton M plugs installed on them? Or do I have to convert everything to Milton V style?
Found the answer at the Milton website:
Quote:
1/4" FNPT high flow V style couplers will accept A, M and V style plugs, however, to retain maximum air flow use V style plugs. Sleeve release is a push type and is easy to use; simply push plug into coupler to engage, pull sleeve back to remove. Perfect for high volume, low pressure applications. V style couplers have a 1/4" basic flow size and a maximum pressure of 300 PSI.
The V coupler is rated at 74 standard CFM, compared to 40 for the M style.
So I will put a V coupler on my compressor and be done with it.
Found the answer at the Milton website:
Quote:
1/4" FNPT high flow V style couplers will accept A, M and V style plugs, however, to retain maximum air flow use V style plugs. Sleeve release is a push type and is easy to use; simply push plug into coupler to engage, pull sleeve back to remove. Perfect for high volume, low pressure applications. V style couplers have a 1/4" basic flow size and a maximum pressure of 300 PSI.
The V coupler is rated at 74 standard CFM, compared to 40 for the M style.
So I will put a V coupler on my compressor and be done with it.
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Originally Posted By: SubLGT
Originally Posted By: George7941
The answer is so obvious, making the question pointless.
Your answer is pointless.
Let me explain. If you had two different examples with two different factors working in opposite directions (larger dia hose vs more restrictive fitting) then the answer is not obvious. In your two examples, everything is the same except one has larger dia hose, so obviously that will flow more. Case closed, nothing to debate.
The answers have been about whether the higher flow hose is necessary in your particular situation, whether you should upgrade to V style fittings etc, only tangentially related to your original question.
Originally Posted By: George7941
The answer is so obvious, making the question pointless.
Your answer is pointless.
Let me explain. If you had two different examples with two different factors working in opposite directions (larger dia hose vs more restrictive fitting) then the answer is not obvious. In your two examples, everything is the same except one has larger dia hose, so obviously that will flow more. Case closed, nothing to debate.
The answers have been about whether the higher flow hose is necessary in your particular situation, whether you should upgrade to V style fittings etc, only tangentially related to your original question.
I work with this stuff a lot. The flow will be virtually controlled by the minimum flow area in the system. As everybody is saying, it's the fittings.
Fittings are just a restriction and flow is NOT "limited" by them... in the sense, 1/4" air line with 1/4" fittings = 3/8" line with 1/4" fitting, is false in common air setups.
Each fitting add to the overall restriction. The air line is usually the greatest restriction, due to length. 3/8" air line with 1/4" fittings is generally sufficient for most automotive tasks: impact, ratchet, die grinder, etc... Whereas for a carpenter, a 1/4" air line would be fine with nail guns. Someone in heavy industry running 3/4"+ impacts and blast cabinets, might need 1/2" air lines.
Each fitting add to the overall restriction. The air line is usually the greatest restriction, due to length. 3/8" air line with 1/4" fittings is generally sufficient for most automotive tasks: impact, ratchet, die grinder, etc... Whereas for a carpenter, a 1/4" air line would be fine with nail guns. Someone in heavy industry running 3/4"+ impacts and blast cabinets, might need 1/2" air lines.
M/I type fittings/nipples do not fit "well" in V-type fittings... they'll plug-in, but will leak if wiggled. Personally I don't care for V-type fittings and their method of sealing, which I feel is not robust. M/I-type have served us well for 30 years in the shop. Plus you loose the benefit of higher flow when plugging in M/I-type.
For truly high-flow I'd consider Prevost or Parkers line of couplers.
For truly high-flow I'd consider Prevost or Parkers line of couplers.
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