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We at G-M feel that this question is best answered using real testimonials from our customers around the world:

G-M Enterprises build “Furnaces that Really Work”, we believe that “Anything Is Possible” you just need some ingenuity and imagination. Our team is built with the understanding that we must “Simply Be Outstanding” . Hey don’t believe us just yet, want to make a bet, then ask American Brazing President Richard Penrose. We are simply outstanding and our furnaces Really work. See some customer testimonials below. G-M Enterprises, because we care and we want to get you up and running with less hassle and maintenance on your part. “Thinking ROI, Thinking Quality, Then Think G-M Enterprises”.


G-M brings an in-depth analysis between external vs. internal cooling comparisons and the positives and the negatives between the two.

External vs. Internal Cooling Comparison

Manufacturers of internal quench would tend to claim that it takes less floor space for internal quench vs. external quench. However, over-all floor space is a push. Internal quench would take more length for the following reasons:
Internal - The vacuum vessel is longer due to the rear mounted heat exchanger, fan and motor assembly. Behind the furnace about 24” to 36” is requires for the removal and/or maintenance of the fan and motor assembly.
External - As compared external quench assemblies would take up more width. The furnace will be able to be place up against the back wall. Additionally external quench assemblies can be configured to take up even less width by installing the blower can in the air at 10:30 or 1:30 on the clock.

Internal - In internal quench the heat exchanger is located in the rear of the furnace between the hot zone and the fan assembly. It is difficult to service the heat exchanger in the event there are leaks.
External - In the external quench the heat exchanger is located outside of the main furnace for easier maintenance and service. In external quench assemblies the large heat exchanger is utilized to handle the heat load effectively, whereas, smaller heat exchangers are used in internal quenches due to limited space.

Rear mounted fan and motor assemblies for internal quench units generally see higher gas temperatures resulting in frequent motor problems as well as the fan going out of balance. This requires higher maintenance whereas in external quench the fan and motor assembly are remotely mounted hence they are exposed to much lower gas temperatures.

There is about a $ 15,000.00 cost savings for the manufacturer of internal quench as opposed to the external quench depending on the furnace size. If a buyer can purchase a furnace with either type of quench at the same price, the buyer is paying $15,000.00 too much for internal quench.

External quench systems will produce 15 to 20% faster quenches as compared to the internal quench due to effective gas flow and larger heat exchanger. External quench is easy to service and maintain as compared to the internal.

G-M elects to stay with external quench systems due to inferior performance and higher maintenance problems associated with the internal quench systems. Some manufacturers started to build furnaces with internal quench as it gave them higher profits as compared to external quenches. If internal quench systems would have been as successful as the manufactures have claimed then they should not be offering external quench systems.


G-M has a complete checklist for possible considerations to ensure furnace effectiveness and efficiency. This results in limiting future operational halts, any maintenance issues, designing of the right furnace, and get the best ROI.


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