fuel hose options

[paulga]

the attached photo show the fuel intake hose to the gen racor is a 1/2" ID rubber hose
I need to buy a similar 3/4" hose. I searched "Gates BRLA 3/4 200 psi" but didn't get an exact match. I only need 2 ft.
so I want to ask where can I cut 2ft of 3/4" fuel hose, or could there be other options such as more pliant hose

 

[Comodave]

You want marine fuel hose A1 rating where fuel stays in the hose. Why do you need 3/4” hose? Don’t you have a Lehman engine? They don’t need anything close to 3/4” fuel hose. More like 5/16 or 3/8”. Defender sells hose by the foot.

 

[paulga]

You want marine fuel hose A1 rating where fuel stays in the hose. Why do you need 3/4” hose? Don’t you have a Lehman engine? They don’t need anything close to 3/4” fuel hose. More like 5/16 or 3/8”. Defender sells hose by the foot.

this is to connect a racor to a manifold
defender's A1 hose is available up to 5/8
does this SAE 30R7 hose or ISO 7840 work?

 

[Comodave]

I don’t know about those hoses. Marine A1 is the recommended hose. What draw do you have that needs 3/4”? You didn’t answer about your engine. I have 450HP engines and don’t have as big as 3/4”.

 

[paulga]

I don’t know about those hoses. Marine A1 is the recommended hose. What draw do you have that needs 3/4”? You didn’t answer about your engine. I have 450HP engines and don’t have as big as 3/4”.

the manifold has 3 outlet: genset hose 3/8, one diesel heater 3/16. The 3rd one is reserved for a second heater. 3/8+ 3/16x2 = 3/4. not likely the genny and heaters would run at the same time though.

I found this one is rated marine A1-15

 

[Comodave]

That would be ok, but why the large hose? Your consumption can’t be anywhere near that capacity.

 

[SeaDogAK]

I’m not sure about your math. You said “3/8 + 3/16*2 = 3/4.” But it doesn’t work that way. Just because you have a 3/8 hose and two 3/16 hoses leaving the manifold doesn’t mean you need a 3/4 coming in. Even if it did work that way, the capacity of a 3/4” hose is far more than 3/8 plus 3/16 plus 3/16 (pi r squared).

 

[Island Cessna]

the manifold has 3 outlet: genset hose 3/8, one diesel heater 3/16. The 3rd one is reserved for a second heater. 3/8+ 3/16x2 = 3/4. not likely the genny and heaters would run at the same time though.

I found this one is rated marine A1-15

A 1/2” hose has almost 20% more cross sectional area than the sum of your three hoses. You do not need 3/4”!

 

[Comodave]

Yup.

 

[O C Diver]

the manifold has 3 outlet: genset hose 3/8, one diesel heater 3/16. The 3rd one is reserved for a second heater. 3/8+ 3/16x2 = 3/4. not likely the genny and heaters would run at the same time though.

I found this one is rated marine A1-15

The way to figure volume flow is to determine the area cross section of each hose (area of a circle [radius squared times pie]).
Your hoses cross sections are:
.11 square inches
.03 "
.03 "
-----------
.17 total square inches. 1/2" hose has a cross sectional area of .196 square inches. My foggy recollection is that 1/2" hose will handle in excess 25 gallons per hour.

Ted

 

[paulga]

yes, i realized last night it should be the sum of squares.
the current FG500 racor's fuel ports are 3/4-16 thread. that might be one reason I picked the manifold with 3/4 inlet.

but is there any downside of using 3/4" fuel hose?

The way to figure volume flow is to determine the area cross section of each hose (area of a circle [radius squared times pie]).
Your hoses cross sections are:
.11 square inches
.03 "
.03 "
-----------
.17 total square inches. 1/2" hose has a cross sectional area of .196 square inches. My foggy recollection is that 1/2" hose will handle in excess 25 gallons per hour.

Ted

 

[O C Diver]

yes, i realized last night it should be the sum of squares.
the current FG500 racor's fuel ports are 3/4-16 thread. that might be one reason I picked the manifold with 3/4 inlet.

but is there any downside of using 3/4" fuel hose?

I can't think of any downside as long as the fuel line is approved for diesel use in boats.

Ted