a littile problem

a hydraulic system has 1" BSP pipe threds (female)eveywhere,on motors, pressure valves,DCVs.

the highest outer Dia. tube can be used is 25mm
wich has a inner dia. 19mm only.

the charts and farmulas shows i need 25mm inner dia. on pressure lines, 30mm I.D. on returen line .

how can i do it.

both ports on motor are 1" BSP, all ports on DCV are also the same so what is the diffrance in pressure and return line since both are having same ports.
what actuly 'returen line' is?



my system requirments are-
maximum flow -180 lpm
max. pressure- 200 bar
system includes only Hydraulic motors,pump,valvs.there are no cylinders in it.

This message has been edited. Last edited by: rock,

quote:

the highest outer Dia. tube can be used is 25mm
wich has a inner dia. 19mm only.

I believe that your confusion is a result of the thread designation.
1" BSP refers to the pipe BORE not the outside dia which is 1.309".

The 19mm bore PIPE ( not tube )would have a 3/4" BSP thread.

Threads

quote:

'returen line' is?

The return pipe to the tank.

Regards Woody

This message has been edited. Last edited by: Woodygb,

What about Pipe length ?
Pressure Drop is basically prportional to:
Pipe Length x Flow in square divided by Pipe ID at the power of 5,
in addition to Friction, Pipe Bends and Viscosity.

The reason pipes hoses and lines are dimensioned, according to the flow is to minimize the pressure drop, delta P, or power losses (heat). Power loss in a line is a function of flow, velocity, viscosity and lenght of line. De lower velocity we can give the fluid the less delta P there will be. A suction line (below atmospheric pressure) are critical, because the risk of pump cavitaion. Pressure lines because of power loss and gain of heat in fluid. Return line is a low pressure line, bringing oil back through returnfilter and to reservoir.

Fluid velocity depends on the flow, GPM and the cross section area. Seeformula on nomographic chart

In a pressure line there will allways be sections with different cross section areas (diameter), due to fittings, bends etc.

It is very common that the fittings at ports will have "smaller" crossarea than the recommended hose/pipe. We even might have to use adapters to upsize from port diameter to hose diameter. It is then very, important to go for the higher recommended hose/pipe diameter. Don't forget that longer hoses/pipes need larger diameter to minimize the total losses. That is one of the reasons the nomo-chart shows a wider range of velocities for recommended diameters.

Seems like 1" (25.4mm) lines will give you about 19ft/sec, which is acceptable according to nomo-chart, 1 1/4" (32mm) will give you more comfy 12 ft/sec...What you choose depends on lenght of line, bends, fittings, cooling capacity, price of hoses, a jump from 1" to 1 1/4" can be significant if 1" takes a 2wire hose and 1 1/4" takes a 4 wire....($$$???)

well , now i am going for 1.25" 'tube' not pipe.
at the pressure line , end connections will be "Weld On" type but--

please tell me few things-

1-- if the port connections and hose end connectors are not big enough ,
can a over size tube make up for flow loses.

the cost of hoses and tubes is not a problem but 'space' is.

2--if i go with 'nomographic chart ' it does not
give any idea about connectors and other fittings.

3-- what is a returen line, is it return line from motor to tank via DCV, filter ,cooler, or it is just DCV to tank via filter , cooler.

if A and B ports on DCV are same dia' if there is pressure on port A then port B is in the return line how can it handle same flow? it will work like a flow reducer?

i worked a lot on this project and i have eleminated all elbows and tees' there are large dia. tube bands in it now.

tubings are not too long they are like tubings on a aspahlt compector.

if i want to connect a hose to a rigid pipe witch fitting should i go for, i found every adaptor has smaller bore then tube and hose.

should i increase the dia. of return line more then 1.25"

FOR WOODYGB--

there are 1" BSP ports .they are for 1" pipe but if i connect a hose on it there has to be an adaptor ,it has thicker walls(the adaptor), problem?

quote:

well , now i am going for 1.25" 'tube' not pipe.
at the pressure line , end connections will be "Weld On" type but--

Sounds good to me

quote:

1-- if the port connections and hose end connectors are not big enough ,
can a over size tube make up for flow loses.

Yes over size tube can help...but there will never be flow losses, unless this causes flow go bypass over relief, which it wont do.....Flow out will always be the same as flow in....however there will be a loss of power.....power is the product of both flow and pressure. If flow is constant we will lose power through lost pressure. see my attached picture/explanation about this.

quote:

2--if i go with 'nomographic chart ' it does not
give any idea about connectors and other fittings.

No this charts dont take that in concideration. But there is help to calculate this...

quote:

3-- what is a returen line, is it return line from motor to tank via DCV, filter ,cooler, or it is just DCV to tank via filter , cooler.

Return line is that line that are connected to tank from the DCV, usually the inline filter is on the return line

quote:

if A and B ports on DCV are same dia' if there is pressure on port A then port B is in the return line how can it handle same flow? it will work like a flow reducer?

If your motor is mono-directional, you can let the return from motor bypass the DCV and let it go straight into return filter via T. plug B-port on DCV.
Edit:
I thought about this mono-directional motor.....if you have inertia on motor, you need to have both A and B lines connected to DCV.....example: a hydraulic chainsaw would be ok, but not a large hydraulic circular saw....


It will not work like a flow reducer, just cause some pressure loss (lost motor efficiancy)

quote:

if i want to connect a hose to a rigid pipe witch fitting should i go for, i found every adaptor has smaller bore then tube and hose.

Go and get this advice at your local dealer
or get back later

quote:

should i increase the dia. of return line more then 1.25"

I would increase to 1.5" minimum

FOR WOODYGB--

there are 1" BSP ports .they are for 1" pipe but if i connect a hose on it there has to be an adaptor ,it has thicker walls(the adaptor), problem?[/QUOTE]

This message has been edited. Last edited by: AKKAMAAN,

quote:

there are 1" BSP ports .they are for 1" pipe but if i connect a hose on it there has to be an adaptor ,it has thicker walls(the adaptor), problem?

Probably not ..
The motor / valve ports will more than likely have been sized with this fitting / tube / pipe mismatch scenario in mind.



Regards Woody

thankyou very much for your time but--

if there is a fitting on motor output port witch is less then perfect bore will it not slowly build pressure just befor itself.

motor power based on pressure diffrence between A and B port , a restriction on flow from motor out will not cost H.P.s?

another thing--
suppose something 10% smaller bore , will it build pressure just before ,roughly how mutch?
will this pressure increase by the time?

does anybody care about this fitting issue?

am i going too far on this ?

I"ll loose more then 2 hp just becouse of fittings . too much ? that 2 hp will become heat . very bad!

This message has been edited. Last edited by: rock,