Sandblasting can be a hazardous job for a variety of reasons from the risks of injury if your equipment is not set up with proper safety gear to the risks of respiratory diseases like silicosis, sandblasting without proper safety consideration is dangerous. To ensure you have knowledge of what is important for respiratory safety when sandblasting we will be covering the respiratory risks of sandblasting and the proper respiratory safety considerations .
Respiratory Safety Risks Associated with Sandblasting
Abrasive blasting’s biggest respiratory risk is a disease called silicosis, which is caused by exposure to the dust and materials that result as a breakdown of materials like sand, rock, and mineral ores. You can learn more about silicosis and sandblasting in our guide here. Ultimately eliminating silica from your blasting is ideal to prevent the potential risks but even with eliminating silica by using a different blast media, exposure to dust from any abrasive blasting media could lead to potential respiratory complications over time. In addition to the potential risks from dust, the air used for sandblasting can also be the potential cause of harmful exposure to carbon monoxide, if your using a respirator that is fed by an oil driven compressor. Carbon monoxide poisoning at its worst can lead to loss of consciousness or even death. Now that we have an overview of the respiratory dangers associated with sandblasting, we can cover OSHA’s requirements on respiratory protection while sandblasting.
Breathing Air Requirements outlined
OSHA provides breathing air requirements for compressed air sources in standard 29CFR, Section 1910.134(i). For compressed and liquid oxygen , the air must meet the standards for medical or breathing oxygen while for compressed breathing air the air must meet a minimum of a Grade D breathing air standard.
Grade D breathing air requirements
1910.134(i)(1)(ii)(A) Oxygen content (v/v) of 19.5-23.5%;
1910.134(i)(1)(ii)(B) Hydrocarbon (condensed) content of 5 milligrams per cubic meter of air or less; 1910.134(i)(1)(ii)(C) Carbon monoxide (CO) content of 10 ppm or less;
1910.134(i)(1)(ii)(D) Carbon dioxide content of 1,000 ppm or less;
1910.134(i)(1)(ii)(E) Lack of noticeable odor.
Options for meeting the standards and specific risks of each option
To meet the air purity requirements for abrasive blasting, you have two primary choices. One is a supplied air respirator that uses a oil free compressor to feed fresh air to the operator, often known as a free air pump. The second option is a supplied air respirator that utilizes the compressed air that will power your abrasive sandblast pot, also known as a high pressure helmet.
Free Air Pump System Example
Compressed Air Filter and Hood
The main risks to be aware of with the free air pump option is that the pump must be placed in a location where it will not be exposed to air that is dangerous for the operator, since the free air pump simply feeds the blast operator whatever air is near it, the air must be pure. The pump must be located away from any potential carbon monoxide or other hazardous gas sources like a running car.
The risks of a supplied air system that uses a oil fed compressor (like the compressor that will feed your sandblaster) is that you must ensure the air is filtered to provide Grade D breathing air, and the air must have less than 10 ppm carbon monoxide present. Keeping the air Grade D quality requires using a proper filter for compressed air and changing the filter out at proper intervals, a filter designed to provide Grade D breathing air is shown below. To ensure there is not excess carbon monoxide present in your breathing air you have to use a high temperature alarm and sample the air frequently enough to determine no carbon monoxide is present, or use a carbon monoxide monitor. Generally speaking, there is not a recommended sampling frequency specified which can make the high temp alarm and sampling method vague and hard to ensure safety. Monitoring for carbon monoxide in your sandblast breathing air supply can be done with a few options, which are highlighted below.
Carbon Monoxide monitoring Options to help with ensuring less than 10 PPM of CO
Hood mounted carbon monoxide monitoring –
The CMS 3 is a hood mounted Carbon monoxide monitor. This unit is convenient because it enables a single operator to safely blast without the need for someone watching a carbon monoxide alarm. The CMS 3 allows a blast operator’s hood to maintain NIOSH approval only with Clemco blast hoods.
External carbon monoxide monitors have the breathing air line run into them and then feed the air out to the operator. These units are convenient because you can easily monitor the breathing air for a few operators at a time. However it is usually best to have someone dedicated to watching the unit, which can often be the pot tender refilling the blast pot. The reason for having a separate person monitor the alarm is that it can be difficult for the blast operator to notice the monitor alarming.