Liquid Dynamics International Ltd. - Piping System Analysis / Piping System Simulation

LDi - P16 / B

Gear Metering smooth systems
Packed Plunger shockless systems

“Totally” smooth gear pump metering systems
Pressure feed to gear meter before bottle installation
Discharge from gear meter before bottle installation
Pressure feed to gear meter after bottle installation
Discharge from gear meter after bottle installation
You are examining to find fluctuations as small as part of 1 psi in several thousand

Example: high viscosity resin/polymer hot oil jacket
Jacketed double layer diaphragm feed pump creates flow fluctuations
Heating circuit pump
Example: 23 tooth gear pump, minimum chance of resonance
Constant supply in – low ripple out
Lifts pressure from 50 Bar to 100 Bar and provides precise flow within 0.5%
All ripple has gone
Metal bellows type, liquid expansion and contraction volume compensator for temperature
change in closed loop circuit
Spinnerette heads 0.1% DQ
Denier checked by laser beam precisely
Web coating

Minimum dead volume, packed plunger pump systems
Packed plunger pumps provide high volumetric efficiency almost no velocity jump shock free injection systems with high pressure capability
Supply
Filter strainer
Heat exchanger
Return
Pump stroke
Acoustics left in pipe
Pump stroke
RV and flow controllers are liable to make more pressure pulsation than a packed plunger pump
For sealed systems the diaphragm seal is behind the packing

Before analyzing system pressure amplitude at frequency and causes, determine acceptable maximums. Below are suggestions. Percentages are of theoretical steady state condition.

Stop drive belt break-up, keep instant load changes less than 14 %
To stop tooth chatter wear, depending on machine inertia, keep pressure transients less than 12%
To stop premature lift and “weeping”, keep all pressure waves that are sustained for in excess of
40 ms below 9% less than static set pressure
Prevent burst disk fatigue by keeping repetitive spikes to less than +/- 4% of steady state pressure
If in doubt stay below 5 psi transient over pressure to stop pipe fatigue, 5%
Examples: 25 ft of 1” pipe with a 100 Hz frequency, keep pulsation below 10 psi. 6500 ft of 20” at 0.5 Hz keep below 30 psi.
6%
60% shaft deflection
Spray blobs have atomization , 5%
Constant streams in fully mixed out
First in first out bad static mixing without continuous flow, 3.5% to 4%
Bobbin in tapered transparent tube, 4%