The model 8520 is designed to mix hydrogen and argon for welding and cutting applications. These include shielding gas for plasma arc welding (PAW) and gas tungsten arc welding (GTAW). A typical example is plasma arc welding of stainless steel tubing in a tube mill.
Because the gas mixer uses a surge tank design, this type of system is ideal for applications that require maintaining a precise proportion from zero flow to full flow with high reliability. The 8520 is suitable for continuous flow or intermittent flow demand.
The model 8520 may be used to mix hydrogen and nitrogen for some applications. The 8520 cannot be used to mix hydrogen and nitrogen for furnace applications since this application requires safety controls per the NFPA 86 standard. Consult Thermco for the suitability of the 8520 for H2/N2 mixing applications.
Thermco Surge Tank System
All Thermco gas mixers use a surge tank. The Thermco surge tank system has the significant advantage of maintaining the accuracy of the gas mixture from zero to full rated flow rate. There is no “minimum” flow rate. Gas mixing systems without a surge tank will have a minimum flow rate below which the gas mixture becomes inaccurate. The Thermco surge tank system is able to accomplish this accuracy without complex control valves or flowmeters.
Safety Shutoff Feature
The model 8520 is equipped with a pressure switch to automatically shutoff the hydrogen in the event that the argon supply is insufficient to create a proper mixture. A light on the front door indicates the shutoff condition. Valving is built into the gas mixer to allow testing of this safety circuit.
Standard Supply Gas Pressure
Gas mixers will be made for supply pressures of 100-125 psig (6.9-8.6 barg) and mixed gas output pressures of 10-50 psig (0.7-3.4 barg) unless ordered otherwise. Gas mixers are often made to special pressure conditions; consult Thermco for details.
Each gas mixer is supplied with one instruction manual which includes wiring and flow diagrams. A data sheet is prepared for each gas mixer specifying major parts of the gas mixer, operating pressure settings and recommended spare parts. Thermco has been providing service on gas mixers since 1964.
Improper use of this product can cause death, serious injury, or property damage. Personnel dealing with this equipment should read and understand warning labels and instruction manuals provided by Thermco. Only personnel familiar with industrial gases should attempt to install or service this equipment. Gases are under pressure and therefore the hazards associated with pressurized systems exist. Gases from high pressure cylinders must be reduced to the specified pressure before entering the gas mixing system to prevent the possibility of equipment damage and personal injury.
Some gases used in this equipment are flammable and therefore constitute a fire and explosion hazard.
Oxygen, toxic, liquid or corrosive gases should not enter these gas mixing systems.
The Model 8520 can not be used for the creation of furnace atmospheres; special gas mixers are available from Thermco for that application. The Model 8520 is intended for welding applications; the buyer should consult with Thermco before applying the Model 8520 to non-welding applications.
Thermco gas mixers are available through many local industrial gas suppliers. Thermco gas mixers may also be ordered directly from the factory. It is especially important to order the correct pressure conditions for the application. If there are questions, please contact the Thermco Sales Engineer.