The principle of mixing Oxygen and Fuel gas within the nozzle of the cutting blowpipe is generally accepted as the best and safest arrangement for cutting mild steel. The safety is enhanced in the design of the nozzle also gives a suction to the Fuel Gas line of the blowpipe.
The Hi-Lo nozzle design illustrated (acetylene version) limits the amount of explosive oxy/fuel gas mixture to the low volume of the drilled and swaged pre-heat passages in the solid copper from which the nozzle is made.
Blowpipes which mix the oxygen and fuel gas using an injector situated near the handle of the blowpipe has a relatively large volume of explosive oxy/fuel gas mixture in the pre-heat tube and any backfire can be much more severe.
Hi-Lo ANM / PNM nozzles are precision manufactured to give an efficient performance and before leaving the factory, each one is individually tested to ensure suction to the acetylene line, quality of the pre-heat flame and accuracy of the oxygen cutting stream.
Note: For operators who require a greater preheat flam, the Hi-Lo Supacut nozzles have been designed and manufactured for the Hi-lo range. However, these do not incorporate the suction feature as shown above.