When looking to understand the difference between welding hoses, one of the most important things to consider is hose size. Generally, there are three common sizes of hoses - "A", "B" and "C". Each hose connection has a matching connecting nut, hose stem and ferrule.
Oxy-fuel applications require left hand nut threads for fuel and right hand threads for oxygen. There is also a "B" size for inert gases; however, the left hand thread configuration of both "B" and "C" sizes are not very common. Whether the standard coupling nut has external or internal threads determines intended gas use. Generally, internal threads are for oxy-fuel applications and external threads are for inert gases, water or industrial air.
Hose Fittings - Sizes and Types:
|Coupling Nut Thread|
|A||3/8" - 24||Left||Fuel Gas||021||X|
|A||3/8" - 24||Right||Oxygen||020||X|
|B||9/16" - 18||Left||Fuel Gas||023||X|
|B||9/16" - 18||Right||Oxygen||022||X|
|B "Inert"||5/8" - 18||Right||"Inert" Gas||032||X|
|B||5/8" - 18||Left||Water/Ind. Air||033||X|
|C||7/8" - 14||Left||Fuel Gas||025||X|
|C||7/8" - 14||Right||Oxygen||024||X|
|C||7/8" - 14||Right||"Inert" Gas||034||X|
When selecting the connection size, the primary consideration should be the gas volume required and if it is a light, standard or heavy-duty application:
All sizes ("A", "B" and "C") using the standard connections discussed have a maximum working pressure of 200 PSIG per CGA E-1 2009.