AXXIOM Manufacturing, Inc. SCHMIDT Operation And Maintenance Manual Download Page 20

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3.8 Abrasive Selection

Abrasive selection is likely the most difficult decision related to the blast operation. Choice of

abrasive is based on factors such as blast application type, desired finish and coating

requirements, characteristics of object to be blasted, cost and ability to recycle, available

equipment, safety, and environmental constraints.

There are many abrasives available that are either natural, manufactured, or processing by-

products. Abrasives are available in varying sizes, shapes, and hardness. These characteristics

determine the resulting effect on the surface to be blasted and limitations of its use. The effects

on the blasted surface are measured by its degree of cleanliness and the surface profile.

Standards and required levels of these measurements are established by organizations such as

Steel Structures Painting Council (SSPC), National Association of Corrosion Engineers

(NACE) and coating manufacturers. See Section 12.5 for contact information of these

organizations. Use these sources to obtain information regarding all aspects of surface

preparation and abrasive selection guidelines.

Schmidt® abrasive blasters are designed for high production open abrasive blasting with a

wide range of abrasives. It is the responsibility of the employer and operators to select the

proper abrasive. It is the responsibility of the employer to make certain that the abrasive

selected is safe to use for abrasive blasting.

Critical:

Always obtain the Material Safety Data Sheet (MSDS) for the abrasive to be used.

The MSDS provides the chemical makeup of the abrasive. Do Not use abrasives containing

toxic materials. Refer to OSHA 29 CFR for acceptable limits of various toxic substances and

additional measures to be taken to protect operating personnel. Always use abrasives containing

less than 1% of crystalline silica. Always use a NIOSH approved respirator when handling,

loading and cleaning up abrasives. Organic substances which are combustible may only be used

in automated blast systems with ventilation that meets OSHA 29 CFR 1910.94.

3.9 Breathing Air Quality

All blast operators must be supplied with and required to use NIOSH approved air-fed

respirators. Breathing air supplied to these respirators must meet Grade D air quality standards

as specified by OSHA 29 CFR 1910.134(i) and the Compressed Gas Association Specifications

ANSI/CGA G-7.1. Consult these specifications when selecting a source of breathing air.

Breathing air must be clean, dry, contaminant-free, and provided at a pressure and volume

specified by NIOSH. Use NIOSH approved air filters on all sources of breathing air. See

Section 3.10.

Breathing air filters do not remove carbon monoxide or any other toxic gases. Use a carbon

monoxide monitor to detect unacceptable levels. Consult OSHA 29 CFR 1910.134(i).

Many sources of breathing air are available such as air cylinders, free-air pumps, oil-less air

compressors, and oil lubricated air compressors. The most commonly used is the same air

compressor that is used for the blast air which most often is oil lubricated. Breathing air

provided by an oil-lubricated air compressor can contain carbon monoxide and therefore

requires the use of a carbon monoxide detector (See Section 3.10). Carbon monoxide can be in

the compressed air produced by an oil-lubricated air compressor when it is operated at

extremely high temperature; therefore, a high temperature alarm is required to alert the

operators when this condition exists.

Oil lubricated air compressors can produce carbon monoxide. Carbon monoxide can cause
asphyxiation and result in death. Use a high-temperature alarm and a carbon monoxide monitor
when an oil lubricated air compressor is used to supply breathing air. Consult OSHA 29 CFR
1910.134(i).