Available signal outputs for Dynisco sensors:
Millivolt (one thousandth of a volt) symbol = mV
Volt (the measure of electric potential) symbol = V
Milliamps (one thousandth of an ampere) symbol= mA
Available ranges for the various signal outputs:
Millivolt= 2mV/V, 3mV/V, 3.33mV/V (other ranges available upon request)
Volt= 0-5V, 1-6V, 0-10V, 1-11V (other ranges available upon request)
Milliamps= 4-20mA, 4-20mA with HART (pressure ranges can be assigned)
4Benefits of pressure transducers
In Plastic Extrusion, pressure variation at the die entrance, could be caused be either an actual variation in rate from the extruder, or variation in temperature affecting viscosity.
Pressure fluctuations are typically controlled with gear pumps
Gear pumps can be manufactured to have pressure transducer ports
Transducers will help the operator make changes to process variables based on pressure readings captured via signal output to instrumentation.
Instrumentation can be programmed to stop the Extruder if a pressure condition exists that will compromise the equipment.
Pressure signals to instrumentation enable control of screen changers that filter out particle contaminates in the melt.
Instruments will monitor and log pressure variations at the die head, providing the operator with data to improve process
• The threads are the industry standard of 1/2-20 UNF
• Improper dimensions will cause thread galling and material leakage
• Insure proper hole dimensions with Gauge Plug included in the Dynisco Cleaning Tool Kit, part number 200100
This is the way a transducer tip should look when it’s new.
Before screen changer
Before melt pump
After melt pump
In the diesVariations in Feed Stock
Prevents pressure build up
Insures adequate melt feed to pump
Insures adequate pump pressure to die
Insures adequate pressure for product
Too close to the feed zone can cause damage from unplasticized pellets
Mounting too shallow in the hole can cause material degradation and freeze-off
Mounting too deep can cause tip damage and measurement errors
Repeated hole cleaning can cause “too deep” holes, and possible tip damage. ( use spacers )
Standard transducers are NOT water tight!!!!
Dynisco circuitry can handle extrusion plant environments, but will not operate when wet
Specify water tight transducers when wet operation is unavoidable
Mounting holes are important ! ! !
They cannot be eccentric
They cannot be too small
They cannot be too large
How deep should transducer be?
Typically recessed around 0.010”
This depth will prevent any unnecessary diaphragm wear and help prolong the life of the pressure transducer
Kit # to make holes…PN 200925
If hole is already too deep, use stackable 45 degree 0.025” copper spacers (PN 633511)
Aluminum also available
Always use a high temperature anti-seize compound when mounting transducers
Always use proper mounting torque
100-200 inch-pounds (8-16 ft lbs) may very on transducer type
500 inch-pounds MAXIMUM (250 for push rod)
RULE OF THUMB…finger tight plus 1/4 turnVariations in Feed Stock
17Transducer Mounting Techniques
To machine a new hole use Dynisco’s Machining Tool Kit, # 200925
Use proper mounting torque upon installation:
See Product Manual
Less causes leaking
More causes seizing and damage to the transducer
18Dynisco ½ 20 UNF machine tool kit (200925)
19Removal of the pressure transducer
• Always remove the transducer while the equipment is HOT
• Remove any polymer residue from the tip by using a cotton rag.
• Do not use the wire wheel on the bench grinder!
• Always remember to clean the hole before reinstalling the transducer
• Use the Dynisco Cleaning Kit # 200100
Bottoming tap - cleans threads
Guide Sleeve/Cleaning Drill - cleans hole
Bluing – checks hole cleanliness and size
Gauge Plug - insures proper fit – Instructions
20Cleaning the mounting hole
ALWAYS remove the transducer before cleaning the barrel with abrasives, cleaning compounds or a wire brush
Remove the transducer with the barrel HOT and wipe the transducer tip clean
Remember to go back and clean the hole with the cleaning drill/guide sleeve
21Clean mounting hole
22Mounting hole review
Dynisco cleaning tool kit (p/n 200100) will make the job easy
Remove the transducers when cleaning the barrel
Remove them when they’re HOT
Remove any plastic buildup in the hole
23Mounting Hole Problems
– Damaged tip
– No response
– Galled threads
– Improper hole
– No anti-seize used
24Mounting Hole to Small
25Mounting Hole to Small
Transducers operate best at midrange.
Transducers can withstand 1.5 times overpressure without damage.
Overpressure can occur when cold material slows the flow.
Verify that your transducer will be operating within their rated range
Pay special attention to the pressure range when extruding different materials
Like people, over-pressured transducers cannot perform their job properly
34Calibrating your transducer.
• When? ------—When it’s up to operating temperature and at zero pressure.
How often?--------When your ISO9000 standards dictate, or if the zero appears to have shifted.
It’s easy! --------Dynisco transducers have a built in 80% R-Cal, and our indicators use this R-Cal to calibrate the span.
35Shunt Calibration “R-CAL”
36How can Dynisco Help YOU?
Stabilize your process
Operate more efficiently
Increase consistency and quality
Help your profitability
Dynisco manufactures for the extrusion industry the most rugged and reliable transducers
Dynisco is an ISO9001 company
Proper care and handling will provide you with many years of service