Zero-Discharge Black Oxide Finishing System

Zero-Discharge Black Oxide Finishing System

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The 30-minute Tru Temp low temp black oxide process is now available in a new zero-discharge configuration designed to eliminate the need for a drain connection.


The Tru Temp system from Birchwood Casey uses ion exchange technology to purify and recycle the rinsewaters, resulting in a “closed-loop” zero-discharge installation. The technology is available for all size systems, including 40-gal, 100-gal and larger capacity custom tank systems.
The systems are said to work well in those installations where it is impossible, or impractical, to send process rinse waters to the drain, such as in facilities with septic systems, or in plant locations inconvenient to city drain connections. The ion exchange system allows the process line to operate as a self-contained system. By recycling the rinse waters, the need for a drain connection and discharge permit is eliminated, the company says.


The primary benefit of the ion exchange equipped Tru Temp system is that the process tanks can be physically disconnected from the drain. The system removes all particulates and dissolved ions from the rinse waters, generating deionized water that is reused over and over. The user gets ultra clean rinse tanks, no discharge to the drain, and near zero water consumption.


Birchwood says its process is an ideal in-house substitute for the 290°F hot oxide process. Operating at only 200°F, the Tru Temp system avoids the hazards of a boiling tank and is safe to install in any area of the plant. 


With a fast 30 minute blackening time, Tru Temp forms a durable, black magnetite finish of .000020-inch thickness. equal to that of hot black oxide. The in-house process streamlines part movement, provides better control of finished part inventory, and enhances ISO accountability. Most important, it gives the user a “same-day turnaround” capability to satisfy key customers and fill rush orders - without raising finished inventory levels, the company says.


Satisfying Mil Spec DTL 13924D and AMS 2485, the Tru Temp process is designed to contain no EPA regulated metals. When a city sewer connection is conveniently located, the process rinse waters are normally sewerable as non-hazardous discharge, without waste treatment. For those installations that require zero-discharge from the system, the Ion Exchange option will satisfy those needs.

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