Achieving Efficiency in Achieving Efficiency in Abrasive BlastingAbrasive Blasting

William P. Nelson

Schmidt Engineered

Abrasive Systems

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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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