(Open pipes present unsafe working conditions and continuous pressure drops in compressed air systems)
Let’s talk for a minute about pressure drops. Normally when the topic of pressure drops is raised, it comes in a context related to proper plumbing and volume supply. (If there are significant pressure drops within a compressed air system, especially those which reduce volume flow, problems will arise with compressed air driven devices.)
But, there is another important aspect of pressure drops which relates to open pipe blow-off, a common homemade remedy for blow-off applications. This aspect has to do with the available compressed air pressure at the exhausting point from the pipe or nozzle. In the case of an open pipe, it requires so much compressed air volume that, there can be a continuous pressure drop from the compressor to the open pipe. However, when a nozzle is installed onto a compressed air pipe, there is a restriction to the flow and the entire pressure drop takes place across the nozzle.
What this means for the blow-off solution is a higher velocity blow-off and a more powerful force from the airflow, with less compressed air consumption.
To think of it another way, imagine the flow of water from your garden hose. If the hose is open-ended and the water is fully on, the flow will be high and the force will be low. But, when you install a nozzle onto the end of the hose the flow reduces and the force increases. This is because the pressure drop in the system is taking place across the nozzle rather than the entire system.
This type of a scenario was taking place in the image shown at the top of this blog. The plastic lines connected to the aluminum manifold were fully open on the end, providing a continuous pressure drop and poor blow-off performance. This, coupled with the maximum operating pressure of similar types of hose being 35 PSI, led to a poor performance in this application.
The solution for this customer was to replace these open pipe blow-offs with EXAIR model 1126 Flat Super Air Nozzles and 12″ Stay Set Hoses, model 9262. The flat airflow of the 1126 Super Air Nozzles provide a highly efficient and forceful blow-off, and the Stay Set Hoses allow for articulation of the nozzles into any position needed.
By replacing these open pipes this customer saved compressed air, added safety (open pipes present an operating hazard per OSHA Standard CFR 1910.242(b)), and improved the performance of their operation.
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