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How loud is a plasma cutting torch?

Plasma Noise Levels

in use will require hearing protection when dry cutting.

In the U.S. Code of Federal Regulations, 29 CFR 1910.95, entitled “Occupational noise exposure“, deals with noise levels in the workplace. Paragraph 1910.95(c)(1) states: “The employer shall administer a continuing, effective hearing conservation program...whenever employee noise exposures equal or exceed an 8-hour time-weighted average sound level (TWA) of 85 decibels measured on the A...” That is why most employers are trying to keep noise below the 85 dB threshold.

How loud is 85 dB?

But 85 dB isn’t that loud. It’s about as loud as a two stroke chain saw about 30 feet away, or about the same as a loud toilet flush 3 feet away. Dry plasma cutting is going to range from around 90 to over 120 dB, which is well above the threshold that will cause hearing damage.

Noise Level Comparison - Click for larger view

How loud a specific system is will depend mostly on the cutting current and the type of cutting table, but also on the gases and nozzle being used. Actual sound pressure levels to reach an operator also depend heavily on how far away he is from the noise source, as well as other environmental factors, such as location and type of walls, ceiling, etc. Noise does tend to bounce around, depending on things like that.

Plasma Noise Level Estimates

Based on actual measurements taken at ESAB, combined with other data that is available on the internet, we have assembled the following chart of estimated sound levels. These levels are estimated at 6’ from the operator, for dry cutting – a typical worst case scenario.

Estimated plasma noise levels by current - Click for larger view

How Much Does Under Water Cutting Affect Plasma Noise Levels?

With sound levels up to 120 decibels, hearing protection is definitely required for the operator and anyone else working near the machine. Of course, plasma cutting on a water table can significantly reduce the plasma sound levels. One commonly referenced Swedish study, from 1994, measured sound levels produced by plasma cutting of 10mm (3/8”) stainless steel at various levels above and below water. While the study did not mention cutting current or distance from the source to the measuring device, it does give a good indication of the relative amount of noise level reduction achievable by submerging the plate. In this case, the measured reduction was from 103 down to 72 dB(A), and was only achieved once the plate was a full 3 inches below water. However, safe noise levels were achieved even at 2” below water.

Plasma noise levels relative to water level - Click for larger view

Unfortunately, under water plasma cutting is only suitable up to about 2” thick material. After that it doesn’t work as well. Therefore, almost all plasma cutting from 600 Amps and up will be above water.  

Posted in Cutting Systems , Tagged with Plasma, Safety, Water Table