The removal of organic and particulate contamination from oxygen and oxygen enriched life support equipment is absolutely necessary to prevent a fire hazard. The ozone-depleting solvent trichlorotrifluoroethane (CFC-113) was the solvent of choice for 25 years to clean naval oxygen systems. This solvent displayed performance and safety characteristics that were uniquely suited for the cleaning of oxygen systems. However, under the terms of the Montreal Protocol and the Clean Air Act, the production of Class I ozone-depleting substances (ODSs) has ceased. Replacement of CFC-113 was a difficult challenge for the Naval Sea Systems Command (NAVSEA) which was tasked to find a non-ozone depleting cleaning agent that equals the excellent cleaning and safety characteristics of CFC-113. Navy Oxygen Cleaner (NOC) is able to meet and in some cases surpass the cleaning properties of CFC-113.

NOC is an aqueous inorganic alkaline solution used in a verifiable precision cleaning process that is adaptable to various skill levels and production throughputs. NOC removes particulate; hydrocarbon oils, greases and fats; and fluorinated oils & greases from metallic surfaces, rubber surfaces and plastic surfaces when applied at temperatures of 120 to 170^oF with agitation. Forms of agitation include use of ultrasonic tanks to clean small component, pumps to flush pipe lines or spray impingement to clean large flasks or tanks. The cleaner is non-foaming, non-flammable in liquid or gaseous oxygen, contains no environmentally regulated material, has no ozone depleting potential (ODP), has no greenhouse warming potential (GWP) and is not a volatile organic compound (VOC). The NOC Aqueous Oxygen Cleaning Process is detailed in MIL-STD-1330D. NOC is manufactured in accordance with MIL-DTL-24800.

The use of the NOC cleaning process by the NAVSEA corporation and its vendors for the cleaning of oxygen systems replaces approximately 64,000 gallons per year of CFC-113.

• NOC is free of toxic and environmentally hazardous (ODS or Global Warming Potential) characteristics. The effluent toxicity of NOC, tested in accordance with EPA-600-4-90-027, is greater than 5,000 ppm.
• NOC is easily recycled (lasting up to 26 weeks in-use) using simple filtration. Associated rinse water is easily recycled using simple demineralization.
• The NOC cleaning process is a cost-effective replacement for CFC-113.

• NOC must be rinsed with water to obtain a residue free surface. Residue remaining from product drying in-place will tightly adhere to the substrate (no dusting will occur). However, residue is non-toxic, non-flammable and non-corrosive.
• NOC has a 12 to 18 month shelf life.
• NOC is not usable for applications where process parameters cannot be established such as dead-end gauges and instruments.

Implementation of the NOC cleaning process starts at about $20K for a small component cleaning process consisting of a cleaning/rinsing/drying console, recycling pumps and filters, and laboratory equipment used during process verification. Most organizations using the NOC cleaning process have recovered implementation costs within 18 months.

Other potential related costs include disposal of unusable cleaner, although some facilities have received permits to discharge unusable cleaner to an industrial wastewater treatment facility or municipal sewer. The following cost comparison of CFC-113 and NOC was provided by NAVSEA.

Assumptions:

• NOC Ultrasonic Cleaning Console (20 gallon tanks) with new overhead crane to handle heavy components costs $100,000.
• NOC cost is $10/gallon (55 gal drum purchases).
• CFC-113 cost is $175/gallon.
• 80 gallons of NOC used annually.
• 455 gallons of CFC-113 used annually.
• Approximately 8 cu. ft. of deionizer resin is used to recycle rinse water annually at a cost of @ $50/cu. ft.
• One batch of components cleaned and verified using CFC-113 (by evaporative NVR) requires 2.25 hour of labor per batch.
• One batch of components cleaned and verified using NOC gravimetric requires 1.25 hours of labor per batch
• 1,000 batches are cleaned annually.
• Labor rate = $75/hr.
• Exhausted NOC disposed of in municipal sewer.
• Exhausted CFC-113 disposed of as hazardous waste at $6/gal.
• The analysis does not account for electrical usage. The difference between NOC and CFC-113 should be negligible. CFC-113 vapor or ultrasonics use refrigeration coils for emission controls while NOC uses an oven for component drying.

Cost Comparison for NOC System vs. CFC-113 System