ZERUST® VCI products prevent corrosion in several ways:

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1. By acting as a protective barrier from external corrosive atmospheric elements such as abrasion, water, dirt, and acid gas pollutants.
2. By emitting Volatile Corrosion Inhibitors that passivate the electron flow between the anodic and cathodic areas on metal surfaces and interrupt the electrochemical corrosion process.
3. By adding water repulsion properties to the metal surface, which inhibit water from permeating the metal surface and providing the electrolyte for corrosion reactions.

The vapor corrosion inhibitor portion of ZERUST® VCI products is made of proprietary chemical formulations that are invisible, odorless, non-toxic, non-reactive, non-flammable, and non-allergenic. These chemical formulations release a corrosion inhibiting vapor that diffuses throughout an enclosure that either contains VCI formulations or is made from VCI materials and settles on exposed metal surfaces to form a microscopic corrosion inhibiting layer.

This protective layer will remain on the surface of the metal if there is no significant, continuous exchange of air within the enclosure. Ideally, there should be less than one air exchange per day (for example, when an electrical cabinet or package is opened briefly and occasionally). Once the metal part is removed from the enclosure, the corrosion inhibiting layer is no longer kept in place by equilibrium with the VCI source, and it dissipates from metal surfaces (typically within about an hour), leaving the metal part clean, dry, and corrosion-free.

The vapor diffusing properties of our corrosion inhibiting formulations offer an important advantage over conventional inhibitor coatings since the traces of these gas molecules penetrate hard-to-access crevices, gaps, and slots. They also cover the surfaces of complex-shaped articles that are difficult to coat. They are adsorbed onto the surface of the metal to form a corrosion inhibiting protective layer that is just a few molecules thick. ZERUST® VCI products may also include acid gas absorbing chemicals in the packaging material to act as a barrier and add another dimension to the protection of the metal content. These “scavenging” chemicals react and neutralize the polluted air that may diffuse through the ZERUST® VCI material. Also used are various combinations of physical barrier properties that optimize the corrosion prevention and physical protection needs of our customers. These may range from plain low-density polyethylene (LDPE) material to combinations of higher strength, higher tear resistance, higher resistance to sunlight or UV, static charge dissipation, and lower diffusion for moisture or acid gas molecules.

ZERUST® VCI products offer corrosion protection without having to be in direct contact with or coated onto the parts that are being protected. Metal parts merely need to be enclosed in or with a ZERUST® VCI product (where airflow is minimized) for protection to occur. With ZERUST® VCI packaging, it is no longer necessary to apply messy oils, greases, and other corrosion protection compounds and incur the cost of their removal.

Nitrates (NO3 – one nitrogen and three oxygen molecules) are compounds that occur naturally in soil. Consequently, nitrates are also present naturally in root vegetables like carrots and potatoes, as well as leafy green vegetables. Nitrates are not generally harmful unless they are consumed in massive quantities. When we eat nitrates, they are converted into nitrites in our digestive system.

Nitrites are also compounds made up of nitrogen and oxygen, but instead of three oxygen molecules, they have only two (NO2). Nitrite compounds combine with other elements like sodium and potassium to make sodium nitrite or potassium nitrite, which are used as preservatives and color fixatives in cured meats. Nitrites are particularly good at preventing botulism – an anaerobic form of bacteria that causes paralysis and death – which is why small amounts of sodium nitrite are required by law to be added to cured meats. Nitrites too, on their own and in moderation, are also generally not harmful.

Sodium nitrite, however, isn’t just a good food preservative, it’s also an excellent corrosion inhibitor. That’s why, when NTIC developed and commercialized the first-ever VCI rust preventative plastic packaging, the active chemical protection system was formulated using common food additives, including sodium nitrite. Conservative chemists generally do not recognize sodium nitrite itself as a vapor corrosion inhibitor because, on its own, it has a vapor pressure so low that it is almost immeasurable. When used in combination with other additives in proprietary ZERUST® formulations, sodium nitrite can be effective “VCI activated”. The ZERUST® VCI effectiveness has been proven in commercial and military applications worldwide, as well as scientifically by recognized standard test methods for vapor corrosion inhibitors used by U.S. and NATO military organizations.

Nitrites in VCI products are a commonly misunderstood safety concern because of the historic use of the specific compound, dicyclohexylamine nitrite (or dicyclohexylammonium nitrite). Sometimes referred to by the brand name “Dichan”, dicyclohexylamine nitrite is a vapor corrosion inhibitor that was first used in VCI paper production in the ’s. Later, in the ’s, toxicologists started to become aware that compounds using both amines and nitrites in combination could lead to the formation of “n-nitroso amines”, which are believed to be both carcinogenic and genotoxic. It is for this reason that VCI products produced in most advanced industrialized nations no longer use dicyclohexylamine nitrite. ZERUST® VCI packaging has never contained dicyclohexylamine nitrite and, furthermore, does not use amines of any kind because they are known to be skin and respiratory irritants.

Depending on the design of the corrosion prevention solution, some ZERUST® VCI packaging products may be produced from low and high-density polyethylene resins that are resistant to vapor penetration. Some atmospheric moisture will eventually find its way into a closed package. The presence of moisture in a package can be expected during shipments across areas of high humidity.

When moisture permeates through the ZERUST® VCI plastic packaging products (flexible and rigid), the moisture is affected by the vapor corrosion inhibitors that are present in the VCI product. As a result, the ZERUST® VCI products inhibit corrosion despite a low level of moisture passing through the plastic. Corrosion problems arise when moisture can enter a package unimpeded by the packaging products, such as through an incorrect closure or a significant hole in the package. For example, when there is a significant breach in the package, the corrosion inhibiting molecules can escape, breaking up the protective corrosion inhibiting molecular layer that had formed on the surface of the metal. Therefore, an unimpeded airflow into the package must be avoided.

If you have any questions regarding the best VCI protection for your needs, we advise consulting a ZERUST®/EXCOR® representative. ZERUST®/EXCOR® possesses wide-ranging testing capabilities, which quickly enable us to determine the optimum method of protecting a given metal item. We also can send samples for customers to conduct their own tests. First, try packing identical parts simultaneously and under identical conditions, one part in a normal film or your current packaging and one in ZERUST®/EXCOR® film. Next, store these parts for several days in the most challenging conditions they will be in, such as high humidity, or move them from warm to cool places in your warehouse, similar to shipping conditions. If the part packed in normal packaging shows signs of corrosion, while the one packed in ZERUST®/EXCOR® VCI film shows none, it can be assumed that the part requires VCI protection.

VCI  Emitters  F.A.Q.

VCI Emitting Device  Frequently Asked Questions:

1. What is an "Emitter"?

VCI Emitters are devices, cups, foams, films, bags, etc. which contain special compounds called VCI 's ( Vapor Corrosion Inhibitors).  VCI's release (emitt) safe compounds, that prevent rust & corrosion, into the surrounding enclosure or package. The physical change of the solids in the emitters to a vapor is similar to the way a mothball works.

VCI is released into the package at a controlled rate so that the corrosion protection provided to the metal(s) is continuous over a period of time ranging from months to several years, depending on the number of emitters deployed, cubic feet rating of the emitting device(s) and the atmospheric conditions.

In the industry of corrosion control, when referring to VCI emitters it is generally accepted that the meaning is a device such as an individually packaged adhesive backed cup or a VCI foam device, small pieces of foam or VCI treated chip of paper, pouches or packs that are used in single applications.

VCI Emitters can be purchased at our VCI store or click here for VCI emitting device information and to purchase online.  Mil Spec VCI Emitters are also available.

It is important to note that our VCI foams, films (plastic poly), vci formulations, vci powder and VCI paper are often used in industrial packaging solutions or " packs" of parts and other metals for prolonged corrosion control.  In general, most of our corrosion control products contain VCIs and emit (release) vapor corrosion inhibitors although these are not normally referred to as 'emitters'.

2. How are Emitters Used?

Emitters are used to protect enclosed metal components (parts or systems made of various metals) from corrosion by placing one or more of the devices in a container, package or other enclosure.  This includes electronics, cabinets, closed bins, re-useable packaging and enclosures of all types.  Computers and other electronic devices, electrical control boxes used for plant equipment, control boxes containing relays, switches, electronic gear aboard ships & airlines, tool boxes, spare parts boxes and storage units, fuse boxes, telecommunications devices, analytical equipment, gun cabinets and any other enclosure that contains metals that will corrode. They are also used extensively in shipping containers and packaging.

3. What Will VCI EmittersDo For Me? Why Do I Use Emitters?

Emitters will save money (and time) for almost any company using electronics or companies that are processing or manufacturing items made from metals. Emitters reduce the incidence of corrosion that would otherwise negatively affect production and product quality in several ways:

Emitters reduce the occurrence of electrical/electronic failures in relays, switches and connectors by preventing corrosion which is the Number 1 cause for failure of electronic and electrical devices.

VCI emitters reduce maintenance by reducing failures, OEM equipment warranty claims and part replacements.

VCI emitters extend the useful life of equipment and parts.

Improve reliability by reducing noise levels, relay chatter and switch reliability and continuity.

VCI protected parts are always immediately ready for use

Reduce accumulation of contaminants. The quality and performance of electronic devices will also improve in that they will look cleaner, function more reliably and have lower electronic noise.

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4. How Does an Emitter or VCI Device Work?

The chemicals (VCIs) which vaporize into a package or enclosure are a blend of special compounds that form a very thin layer, only a few molecules thick, on the surface as they interact with all metals present. These chemicals are NON-hazardous and unique in that they prevent the interaction of:  air, water, moisture or contaminants with the metal, thus preventing corrosion. The VCIis pro-active in that it actively seeks out and protects all metal surfaces.

5. How Long Does it Take for an Emitter to Become Effective?

This will vary somewhat depending on the size, shape and temperature of the enclosure. At room temperature, emitters begin working immediately for metals in close proximity to the VCI emitter but it may require as much as 24 to 36 hours for metals at the farthest ends and internal spaces to be protected with VCI vapors.  In some cases a 'boost' treatment of VCI spray or fogging is recommended prior to closing the enclosure.

6. How Can I Have My VCI Emitters Effective Sooner?

This can be done in several ways:

By using more than one emitter and locating them evenly distributed throughout the package or enclosure.

By fogging the entire package initially with one of our VCI powders, VCI spray, fog or direct application to the metal parts.

By treating some of the internal components with a VCI rinse or cleaner, such as a VCI degreaser , VCI temporary coating ,ElectroSpray or VCI enhanced rinse before placing them in the container or enclosure.

By increasing the temperature of the parts or atmosphere.

7. Are Emitter Vapors Hazardous?

Our VCI emitters contain natural compounds which are not hazardous, toxic or flammable.  Some of the chemicals are very similar to compounds that are been used in foods and beverages.

8. Are Emitters Environmentally Safe?

Our VCI emitters, like most of our products, are environmentally and workplace friendly and do NOT CONTAIN any known environmentally restricted or harmful compounds.  

9. How Do I Remove VCI Emitter Films?

The films left by vci emitters are only a few molecule thick (~ 1/500,000 th of 1 mil). They are much thinner than most contamination layers which form on virtually any surface. It is not necessary to remove them and they have little effect on adhesion, subsequent coatings or use as the VCI film leaves the surface of the metals within a few days after the emitter is removed from the package.

10. What happens to VCI Emitter Vapors When the Box is Opened and Closed?

Some of the vapors will escape when a container is opened, but the VCI's already adsorbed on the metals will not be disturbed immediately. They will continue protecting the metal. As soon as the container is closed, the VCI emitter will again replenish the container with Vapor Corrosion Protection.

11. How Many Times Can the Container Be Opened and Closed Before Depleting the Emitter?

This depends on the chemical contaminants in the atmosphere, relative humidity, temperature and a number of factors.  For average conditions, if all of the vapor is lost from the container and all of the VCI escapes from all of the metal surfaces in the container, the container can be opened and closed approximately times or 10 times a day for one year! (1-3 times a day for two years.)

12. What About Enclosures/Cabinets/Boxes Which are Not Completely Sealed?

The lifetime of the device will be somewhat shortened, possibly to one year or less.  Although emitters are specified for "enclosures" they will still provide protection for systems which have some air flow through them. The degree of protection will depend on the level of contaminants in the air and the rate of air exchange.  The amount of VCI is already adsorbed on metal components will not be easily displaced. Once they have been coated with VCI, protection will continue for a considerable time that will vary due to local conditions.

13. What About Cabinets With Fans or Other Forced Air Throughput?

The lifetime of the devices will be shortened but they are still able to provide excellent corrosion protection. The emitter will need to be changed more frequently depending on the rate of air flow, the quality of the air flowing through the cabinet, temperature and contaminants. This protection is best achieved by allowing the VCI vapors to perform (coat the metals) with the forced air turned off, during downtime when the fan or forced air can be turned off, such as over the weekend or evenings.

14. How Do VCI's Affect Electrical Characteristics Such as Resistance, Dielectric Strength, etc.?

Available testing and use of VCI's used in emitters to date indicate that VCI's have no adverse effects on electrical parameters. In fact, Independent Testing Laboratories have shown that when VCI emitters are used, the contact resistance of relays and contacts remains much lower because they inhibit oxide and contaminant build-up on the contacts. Other tests have indicated no increase of leakage currents at any point on PC boards or electrical circuitry.

15. What About VCI's on High Frequency Equipment?

VCI emitters do not adversely affect the performance of RF equipment.

16. What About Using Emitters in High Voltage Equipment?

VCIs have been used in equipment which has operating voltages exceeding eV. We expect that if they are used at higher voltages there will also be no adverse interactions. In fact they will minimize formation of corrosive components, which extends equipment life and efficiency.

17. Do Emitters Provide Desiccant Activity?

VCI emitters do not provide much in the way of desiccant activity.  VCI emitters function pro-actively to seek out metals and provide a corrosion protective "skin" or layer on all metal surfaces.   This layer impeeds the normal destructive reactions which otherwise occur with moisture and other contaminants.  Although VCI emitters can be used effectively in conjunction with desiccants, in our experience we have found that desiccants are normally not required to achieve corrosion protection.

18. Are Emitters UL (Underwriter Laboratory) Approved?

UL approval is primarily a requirement for fire characteristics. Our VCI emitters presently do not have a UL approval, although there have been very few requirements for such.

19. What About Use of Emitters Under Harsh Conditions?

VCI emitters have been used very successfully under extremely adverse conditions, including remote control switch and relay boxes located near the sea, oil platforms, underground mining equipment, aviation equipment, aerospace, electric and public works utilities and atmospheres containing over 200 ppm of mixed acids such as SO 2, H, S, HCL, etc., and in control boxes in harsh industrial atmospheres of +80 degrees F, RH of +80 %.

20. What About Protection of Silver, Gold, Tin and Other Metals?

VCI emitters use a unique blend of several different chemicals to provide a corrosion inhibitor with one of the widest ranges of protection possible. They are multi-metal inhibitors and will protect most metals under many conditions.  We also carry lines of products such as special films and special papers for the protection of specific metals if required for the specific application.

21. What Are the Effects of Higher Temperature?

The higher the temperature, the faster the VCI will release its corrosion protective ions into the enclosed atmosphere. (emit a protective vapor) Corrosion Protection will be effective in faster and more pro-act ively then a lower temperature.  The enclosure will be saturated with VCI protection within less time but t he VCI will also be depleted at a faster rate.  At an operating temperature of 125 F to 150 F useful lifetime and period of corrosion protection will be shorter. When emitters are used continuously at these higher temperatures we suggest that they be replaced more often say once per year or more. We have also found that certain constructions of VCI emitters such as our MDE-30 emitters withstand continuous high humidity and higher temperatures much better than others.

22. How Do I Know When the Emitter is "Used Up"?

There are several ways to determine if an emitter is still useful, but these methods are so costly that we recommend automatically replacing the emitter once every two years. The emitter should be replaced more frequently than this if the conditions are severe or there is significant leakage (air exchange), high temperatures or loss of the internal air through frequent opening and closing.

If it is a powder containing emitter or a VCI pouch or sachet is simple to determine if there is powder left in the emitter simply by shaking it. Or, if there are signs of corrosion beginning on the equipment, it is most likely that the powder in the emitter has depleted.

23. What About Using VCI Emitters in Older Equipment?

Although emitters will not reverse prior corrosion, when they are used in older equipment, they will extend the useful life of parts & equipment reduce failures and reduce further incidence of corrosion. For help to select the right VCI emitter click here.

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