## FRICTION LOSS THRU .25" ID TUBING

## FRICTION LOSS THRU .25" ID TUBING

(OP)

I AM LOOKING FOR FRICTION LOSS DATA ON .25" SS TUBING. THE VISCOSITY OF THE LIQUID IS 17,000 CPS, THE FLOW RATE IS 1 LB/MIN. WE ARE TRYING TO PUMP THRU 4' OF .25" SS TUBING THEN THE CUSTOMER WANTS TO PUMP THRU A .080" ORIFACE. I CANNOT FIND FRICTION LOSS DATA FOR 1/4" TUBING TO VERIFY IF THIS IS EVEN POSSIBLE. CAN ANYONE HELP.

## RE: FRICTION LOSS THRU .25" ID TUBING

Darcy-Weisbach equation ( LV)2

friction loss= f ----------

D2g

where

L = pipe length - ft

D =average inside diameter of pipe - ft

V =average pipe velocity in ft/sec

g =gravitational constant (32.174 ft/sec squared)

f =friction factor (dimensionless number that depends on the roughness of pipe

ID and the Reynolds number)

With the viscosity you state, I believe you will have laminar flow (Reynold's number below 2000) so the roughness of the pipe ID has no effect and your friction factor would become:

64

f = ----------

R

where

VD

R = Reynold's number = -----------

v

where

V and D as above

v = Kinematic viscosity - ft squared/second

If your Reynold's number is below 2000, you have laminar flow. If it is above 4000, the flow is turbulent and you will need to determine the friction factor. That is more involved an requires yet another calculation using the Colebrook formula, unless you have access to further data about the 1/4 ID tubing. For that, you might try the vendor of the tubing.

More information is also available from the Hydraulic Institute and their Pipe Friction Manual. See their website at www.pumps.org.

Regards and good luck, Jeff Helm

## RE: FRICTION LOSS THRU .25" ID TUBING

h = (f L/D) V

^{2}/(2g)In the above form, a loss coefficient (for valves, fittings) can be substituted for (f L/D).

## RE: FRICTION LOSS THRU .25" ID TUBING

Regards, Jeff