What Is Entrainment?

Entrainment is defined in the simplest of terms as: to draw in and transport (something, such as solid particles or gas) by the flow of a fluid.

EXAIR’s Intelligent Compressed Air® products use the principle of entrainment to give you more volume than the compressed air being introduced from your air compressor.  This is very important considering that the standard cost for compressed air is $0.25 per 1,000 Standard Cubic Feet (SCF) and is commonly called the 4th utility. Any pipe, manifold, or fitting can be modified to blow compressed air, however, these homemade blow offs will be very noisy and waste a tremendous amount of compressed air.  In contrast EXAIR’s intelligent compressed air solutions are engineered to be very quiet and use conservative amount’s of compressed while multiplying the output volume through entrainment.  They also comply with OSHA safety standards.

Let’s consider the EXAIR Model 1100 Super Air Nozzle as an example. It comes with either a 1/4 MNPT or 1/4 FNPT threads and will produce 13 ounces of force at a distance of 12″ from the nozzle. All while consuming a relatively modest 14 SCFM of compressed air. To produce that much force using that small amount of air, the Super Air Nozzle is intelligently designed and manufactured to exacting standards to maximize the entrainment of the surrounding ambient air.

To explain how this works compressed air is used to induce the primary air flow. This primary air flow is a high velocity jet of air that creates a low pressure area around nozzle which entrains the ambient or free air. The air streams combine past the tip of the nozzle creating a powerful blast of air. The Super Air Nozzle can entrain air up to 25 times more than the primary compressed air feed.  All EXAIR’s Super Air Nozzle’s create this level of air entrainment.

AirflowAnimation
EXAIR Super Air Nozzle entrains ambient air up to a 25:1 ratio

In addition to entraining a significant amount of air, the Super Air Nozzle also reduces the noise level. Most homemade nozzles are not well constructed so, the hole(s) that allow the air to escape may have sharp jagged edges which will induce noise or turbulence. Even commercial nozzles with cross drill holes create a tremendous amount of wind shear which leads to an ear splitting compressed air squeal. The smooth design of the Super Air Nozzle creates a laminar flow of air that reduces the noise of the nozzle to 74 dBA at a distance of 3′ from the nozzle. For reference a 1/4″ open tube can easily create noise levels over 100 dBA. Using EXAIR compressed air nozzles can greatly reduce the amount of noise in and around your shop.

Last but certainly not least the EXAIR Super Air Nozzle complies with OSHA standard 29 CFR 1910.242, which requires that all nozzles that use compressed air over 30 PSIG must provide a point of relief in case the nozzle is dead ended and OSHA Standard 29 CFR – 1910.92 (a) for maximum allowable noise exposure. EXAIR Super Air Nozzle uses multiple orifices that are recessed, so that the air always has a path of escape. Many homemade nozzles do not have any provision to protect from dead ending and are very loud which does not comply with the OSHA noise standards.

If you would like to discuss increasing the efficiency of your compressed air usage, quieter compressed air products and/or any EXAIR product,  I would enjoy hearing from you…give me a call.

Steve Harrison
Application Engineer
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