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U22

Parker Hannifin Corporation

Tube Fittings Division

Columbus, Ohio

http://www.parker.com/tfd

4300 Catalog

General Technical

Dimensions and pressures for reference only, subject to change.

Tube Fittings Pressure Drop

Inhydraulicsystems, pressuredrop represents lossof energyand

therefore should be kept to a minimum. Pressure loss in straight

tubing and hose is mainly caused by the frictional resistance

of the walls, while in fittings it is mainly caused by changes in

the magnitude or direction of the fluid velocity. Mathematical

analysis of pressure drop, even though possible, may not be

exact because of the interrelationship of factors such as fluid

density, velocity, flow area and frictional co-efficients.

The following pressure drop charts were derived from actual

test data and may be used as a guide for determining pressure

Examples:

drops at various flow rates through fittings for fluid indicated. To

determine pressure drop for a given flow, trace a vertical line up

from the flow axis to the desired size line then trace a horizontal

line from this intersection over to the pressure drop axis.

Example:

A size 8 CTX, with oil, similar to the test fluid, flowing

through it at 4 gallons per minute, would cause a pressure drop

of approximately 2.3 psi. Conversions will have to be made for

fluids which are not similar to test fluid.

The Tube Fittings part numbers are listed below the Pressure

Drop Chart to which they apply.

Fig. U2 — Pressure Drop Chart for 90° Fittings or Branch Path Through a Tee or Cross Fitting (Triple-Lok)

Pressure Drops for Other Fitting:

*These pressure drop curves were established with Triple-Lok fittings. The pressure drop values can be adjusted for other

fittings of the same size by multiplying the value from the chart by the ratio of Triple-Lok flow diameter to that of the other

fitting, raised to the 4

th

power.

Example:

Find pressure drop for 6C5L at 5 gallons per minute flow rate:

From the chart, the pressure drop for 6C5X is 10 psi.

Also, the ratio of 6C5X to 6C5L flow diameters is 0.297/0.264, or 1.125.

Therefore, the pressure drop for Seal-Lok = 10 x (1.125)

4

= 16 psi.

Pressure Drops for Other Fluids:

Pressure drop through a fitting is mainly caused by change in direction and velocity of the fluid. Therefore, it is directly propor-

tional to the specific gravity of the fluid. The drop due to friction, which is dependent on the viscosity of the fluid, is so small in

this case that it can be ignored. Thus, the pressure drop with a different fluid can be calculated by multiplying the value from

the graph above by the ratio of specific gravity of the two fluids, or:

New Drop = Value from the graph x Specific Gravity of New Fluid

Specific Gravity of Test Fluid (0.873)