Plasma Cutting LEV – Controlling the Risks

May 30, 2019

With advancements in technology making plasma cutters more accessible and economical, they have become commonplace in a range of different industries; providing a faster, safer and more precise alternative for cutting metal to traditional manual welding torches.

Plasma cutters are used for the cutting of various materials including stainless steel, copper and aluminium, all of which release harmful fumes and gases during the cutting process.

The powerful arc of plasma results in most of these fumes being emitted below the plate being cut. As a result, downdraft high-volume local exhaust is necessary for effective control if dry cutting is carried out.

Find out more about controlling the risks of inhalation whilst plasma cutters are in operation in your factory, workshop, R&D centre or another working environment where plasma cutting is utilised.

Why Are Plasma Fumes, Dusts & Gases Dangerous?

The fumes, dust and gases created during plasma cutting pose a number of risks to operatives if not adequately controlled including:

  • Fume inhalation – Ailments will vary in severity dependant on the type of metal being cut but may include headaches, eye, nose and throat irritation, dizziness and nausea. Prolonged exposure to dust and fumes can cause serious health conditions such as lung damage and cancers.
  • Gas inhalation – Failure to control gases in confined spaces can result in asphyxiation.
  • Gas combustion – Failure to control gases in confined spaces can pose a fire risk.

Controlling Plasma Cutting Fumes with LEV

Local Exhaust Ventilation (LEV) should be installed in environments where plasma cutting takes place and a risk has been identified. It is most appropriate for use at lower powered mechanised systems or hand-held cutting systems.

Whilst mechanised systems are available, the majority of plasma cutting equipment is operated manually; thought should be given to the type of cutting being used when determining LEV requirements:

Handheld Plasma Cutters

Handheld plasma cutters are smaller handheld tools generally made up of a power source and a torch, they are operated by a person and are most commonly used in vehicle repair and heavy fabrication environments.

In order to prevent operatives of handheld plasma cutters inhaling dangerous dust and fumes, LEV should be installed. Systems similar to those employed to control welding fumes are not always appropriate since welding fume requires lower air volumes to control the contaminant and the dust loading of plasma is much higher. Extraction should be placed very close to the source of fumes and gases, and with a long cut, will require frequent repositioning

Mechanised Plasma Cutters

Mechanised plasma cutters are generally significantly larger and more complex in comparison to handheld plasma cutting systems. Being fully automated, a mechanised plasma cutter will usually provide a more precise and consistent cut.

Within a mechanised cutting system, LEV can be built into the table supporting the cutting grid or bed. In order to ensure adequate control, a capture velocity of at least 0.75metres/second measured at the position where the fume is produced will be required.

As mechanised cutting beds are often large, this could result in very high volumes of air being extracted. To prevent this, designs are available which utilise a series of chambers built into the table, within these LEV designs, the position of the torch activates damper which creates air flow only in the chambers in the vicinity of the torch.

Alternatively, systems can be designed which connect the chambers to the exhaust via a section of duct which moves in sequence with the torch along a fixed duct with a slotted rubber cover.

Please note, all plasma cutting LEV systems will require regular maintenance in order to ensure effective operation.

Underwater Plasma Cutting

In order to reduce noise, some operations utilise underwater plasma cutting which involves building a mechanised cutting machine within a water bath which is then flooded before use.

According to HSE, cutting underwater not only allows for the noise level to be reduced to below 80dB(A), but can also reduce fume levels to 10% in comparison to dry plasma cutting.

However, this is not always a viable option as the speed of cutting is reduced as is the thickness of material that can be cut, reducing capability and efficiency.

Proper LEV System Maintenance

In order to continue operating effectively, your LEV system should be regularly maintained and inspected by a professional at least every 14 months. Where dust, fumes and gases from plasma cutters are being controlled, particular attention needs to be paid to damage, potential leaks and blockage of filters.

Additionally, the rate of extraction at the intended operating position should be periodically (at least every 6 months) tested and compared to the LEV design standard or commission report.

Experts in Plasma Dust and Fume Extraction

At Vent-Tech, we offer an end to end LEV service, from design and installation to regular servicing and testing to ensure that your LEV is providing the best performance based on your operation. If you require more information about controlling plasma cutting fumes, dust and gases, give one of our expert team a call today on 0117 964 7945 or fill out a contact form and we’ll get back to you.