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Fluid Flow Control Animations
Fluid Flow Control Animations

pencil - write your answer down Find the "F" Value that applies to Your Pump Type
"F" is a correction Factor on the square of number of displacers.
Example, Centrifugals are intrinsically good - have a high F,
Sandwich diaphragm metering pumps have a low F.

F = 7
A centrifugal pump has 11 blades, at 725 RPM it Displacers 500 gpm,
500 gals x 231 in3 per Gallon / 11 blades x 725 rpm = 14.5 in3 displacement
@ 133 Hz.
F = 5
A gear pump has 17 teeth, @ 440 rpm it produces 2 Kg per Second
2 Kg per second x 60 secs per minute x 1000 gms per Kg / 17 teeth per rev x 440 rpm x SG 1.35 = 12 cm3 per tooth
@ 125 Hz.
F = 3.0
A vane pump with 23 vanes, driven at 2,900 rpm, pumps 380 barrels per day
40 Liters x 1000 cm3 per Liter / 23 vanes x 2900 rpm = 0.6 ml displacement
@ 1,111 Hz.
F = 0.4
A quintuplex plunger pump turned at 880 rpm, generates 60+ M3 per 8 Hr shift
2000 gals per hour x 3,800 ml per gallon / 60 minutes per Hr. x 5 piston per rev x 880 rpm = 28.8 ml/stroke
@73.5 Hz.
F = 1.0
A tri-lobe pump at 173 rmp, discharges 3 tons per hour
100 lbs per minute x 25 in3 per pound / 3 lobes per rev x 173 rpm = 4.8 in3 per lobe
@ 8.7 Hz.
F = 0.8
F for duplex diaphragm heads also = 0.8
A simplex diaphragm head pump is pushed by a 100 mm diam. piston with a 150 mm stroke @ 205 spm
5 cm Piston Radium x 5 cm pist. rad. x (Pi) 3.142 x 15 cm stroke = 1.18 Liters per diaphragm stroke
@ 3.4 Hz.
F = 1.8
The F figure assumes that the air supply to the A.O.D.D. is enough to ensure no return stroke delay.
An air operated double end diaphragm pump empties a 40 gals. drum in 4 mins., on a 2 second cycle
10 gals per minute x 231 in3 per gallon / 2 diaphragms per cycle x 30 cycles per min. = 38 in3 per end
@ 1.0 Hz.
F = 0.4
The F figure assumes that the size of the shoe or wheel is approx. one third of the volume between shoes or wheels.
A hose pump squeches out 150 liters of effluent sludge per minute, with 3 shoes revolving 15 times per minute.
150 liter / 3 shoes x 15 revs = 3.33 liters between shoes
@ 0.75 Hz.
F = 0.6
Triplex Quad and Quin versions of this type of pump, particularly when used at pressures above 100bar (1500psi), have a phenomenal tendency to create huge pressure disturbances, and high frequencies from interaction within the manifold. The F factor of 0.5 is stated to cause additional damper size to allow for the greater level of pulsation that might not be expected. Special OCTOPUSSY replacements for the pump manufacturers interconnection manifold are available.
F = 1.15
Packed plunger pumps generally have the least dead space within the pump head and the smallest check valve pocket dead volume, they therefore have the best volumetric efficiency . Accordingly the accelerate the liquid into the system form the beginning of stroke. The gradual acceleration produces the lowest level of pipe reaction and so the least level of pressure pulsation. For this reason the F factor number is highest of all rotary drive motion reciprocating machines.
F = 1.3
Fluid driven differential area pressure intensifiers generally have two features which result in lower levels of discharge pulsation than might otherwise be expected.
A). The ratio of stroke length to diameter is wide. This results in minimal dead volume. B). The return stroke is normally faster than the discharge stroke, so the volume necessary to sustain flow in less than would be required for an equal discharge and return stroke machine. Hydraulically driven versions are highly energy efficient also.
That is why the F factor in better, causing a smaller damper selection.

e - "SOLID STATE" or "NO MOVING PARTS" DAMPERS are rated with an "e" number in the tables of standard WAVEGUARD dampers. The "e" number denotes an equivalent volumetric compressibility to a volume of a gas
such as Nitrogen . The e that is stated in the tables assumes the equivalent of say a hydrocarbon liquid with a 0.8 cP and 0.8 SG. at ambient pumping temperature. That is like saying the compressibility of water at 220 degrees F and 15psig. When you have determined the nominal volumetric size of the damper that your pump system deeds, then if you need a no moving parts damper, and you wish it to do volumetric damping as well as high frequency pressure pulsation interception, you may use the e number as the basis of your selection. You will have to extrapolate according to the relative compressibility of you liquid, to the examples given. Cold hard liquids will need a larger device, Hot soft liquids need smaller devices. Otherwise simply choose by the damper connection size.

A Nomogram - or "3 axis Graph" (PDF file) - to help you specify allowable residual pressure fluctuation


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Return to the beginning of PulseGuard, pulsation dampeners

Selecting Pulsation Dampeners for Different Pump Systems.
Flow through pulsation dampers are at least 3 times more efficient than T off line accumulators.
Dampeners that do, flow goes through, but pressure pulsation does not.
PulseGuard Pulsation DampersThe Smooth Flow People

Call Toll Free 1-888-DAMPERS (326-7377) / See also: Pulsation-Dampeners.com for a pulsation dampener.

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