achieving efficiency in abrasive blasting william p. nelson schmidt engineered abrasive systems...
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Achieving Efficiency in Achieving Efficiency in Abrasive BlastingAbrasive Blasting
William P. Nelson
Schmidt Engineered
Abrasive Systems
Sponsored by:
What is the Definition of What is the Definition of “Efficiency”?“Efficiency”?
Abrasive blasting is defined as a Abrasive blasting is defined as a controlled erosion process whereas your controlled erosion process whereas your productivity is measured by how much productivity is measured by how much area is blasted, in what time frame and area is blasted, in what time frame and by using how much abrasiveby using how much abrasive
What is Abrasive What is Abrasive Blasting?Blasting?
““To combine the energy of compressed To combine the energy of compressed air with a granular abrasive, which is air with a granular abrasive, which is propelled to impact a surface in a propelled to impact a surface in a controlledcontrolled, , repeatablerepeatable and and predictablepredictable surface preparation method.”surface preparation method.”
Enemies of any Air Blast Enemies of any Air Blast SystemSystem
Insufficient air supplyInsufficient air supply
MoistureMoisture
Pressure dropPressure drop
Enemy #1Enemy #1Insufficient Air SupplyInsufficient Air Supply
You lose 1.5% of productivity for every 1 psi You lose 1.5% of productivity for every 1 psi
reduction in blast nozzle pressurereduction in blast nozzle pressure
(As stated in research by NACE)(As stated in research by NACE)
Enemy #1Enemy #1Insufficient Air SupplyInsufficient Air Supply
NOZZLENOZZLE No. 4No. 4 No. 5No. 5 No. 6No. 6 No. 7No. 7 No. 8No. 8
Orifice SizeOrifice Size 1/4”1/4” 5/16”5/16” 3/8”3/8” 7/16”7/16” 1/2”1/2”
CFM @ 100 psiCFM @ 100 psi 9090 150150 200200 270270 350350
(All figures are approximate)(All figures are approximate)
Enemy #2Enemy #2MoistureMoisture
Increased operating costsIncreased operating costs
Increased material costsIncreased material costs
Decreased operating efficienciesDecreased operating efficiencies
Reduced productivityReduced productivity
Enemy #2Enemy #2MoistureMoisture
How does water get into the compressed air?How does water get into the compressed air?
All air contains moistureAll air contains moisture As the air is compressed, any moisture in it will As the air is compressed, any moisture in it will
also be compressedalso be compressed As you compress the air/moisture, it heats upAs you compress the air/moisture, it heats up Hot air retains moisture remaining a vaporHot air retains moisture remaining a vapor
So…How do you remove moisture?So…How do you remove moisture?
Enemy #2Enemy #2MoistureMoisture
Convert moisture from a vapor to a solid (water droplets)Convert moisture from a vapor to a solid (water droplets)
HOW?HOW?
By cooling the air you can then remove the moisture:By cooling the air you can then remove the moisture:
► ► By expansion (Moisture Trap)By expansion (Moisture Trap)
► ► Use of radiator (ACS)Use of radiator (ACS)
Once the air is cooled, you have to separate it:Once the air is cooled, you have to separate it:
► ► Demister PadDemister Pad
► ► CentrifugalCentrifugal
► ► Absorption / AdsorptionAbsorption / Adsorption
Enemy #2Enemy #2MoistureMoisture
3” Air Inlet
1) 3” Outlet 2) 2” Outlet 4) 1” Outlet
Aftercooler Aftercooler SystemSystem
Enemy #2Enemy #2MoistureMoisture
1500 CFM
Air Compressor
Water Volume in Air
75° Ambient Air
75% RH
270 gal./day
200° 90°
90 Gal/day
180 Gal/day
Enemy #3Enemy #3Pressure DropPressure Drop
NozzlesNozzles
Hoses; Blast & AirHoses; Blast & Air
Restrictive PipingRestrictive Piping
Enemy #3Enemy #3Pressure DropPressure Drop
Nozzle Wear
Hoses & Set-Up
Enemy #3Enemy #3Pressure DropPressure Drop
AutoAuto
AirAir
ValveValve
Enemy #3Enemy #3Pressure DropPressure Drop
High-FlowHigh-Flow
AutoAuto
AirAir
ValveValve
Proper Set-UpProper Set-Up
Difference of Control Difference of Control System TypesSystem Types
PRESSURE HOLDPRESSURE HOLD
NON-PRESSURE HOLDNON-PRESSURE HOLD
Non-Pressure Hold SystemNon-Pressure Hold System
Pressure Hold SystemPressure Hold System
Fine Tuning an Abrasive Fine Tuning an Abrasive Blast SystemBlast System
Adjustments can be made to the following for Adjustments can be made to the following for enhanced productivity:enhanced productivity:
Abrasive meteringAbrasive metering
Minimizing pressure drop & increasing air flowMinimizing pressure drop & increasing air flow
Hose length, hose size, couplingsHose length, hose size, couplings
Nozzle sizeNozzle size
Moisture in airMoisture in air
Achieving Efficiency in Achieving Efficiency in Abrasive BlastingAbrasive Blasting
THANK YOU
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