PPG Aerospace PRC-DeSoto PR-1422 Class B Brown Fuel Tank Sealant
The PR-1422 Class B Fuel Tank Sealant is a great choice for fillet-type sealing and large areas, particularly fuel tanks. It has several beneficial characteristics, e.g. a large service temperature range between -65 and 250 degrees Fahrenheit.
And you'll be happy to know that PRC-DeSoto put this sealant through serious paces in order to determine for you how well its adhesion will stand up to the common abuses of aviation life. Imagine an environment of salt water simmering at 140 degrees Fahrenheit. It sounds almost like primordial soup for sealant to deal with. But PR-1422 class B can and it will endure.
Throw the hardened rubber in there. Wait a full 20 days, then take it out and see what's left. According to DeSoto, what emerges is a substance that hasn't caved in the face of corrosives. It also will not soften, blister or lose adhesiveness. It's just slightly harder in its final form than PR-1400. But they are both strong products. PR-1422 will stand up to aerial adversity.
Read the PR-1422 Class B Technical Data Sheet.
PRC and Pro-Seal Aeroscape Sealants Application Guide
PRC-DeSoto International PRC®, Pro-Seal®, Permapol® P-3 brand products are designed for interior/exterior aircraft sealing and coating applications. The traditional Polysulfide and the high performance Polythioether compounds are used for fuel tank sealing, corrosion inhibition, aerosmoothing, electrical insulation, windshield/canopy sealing, priming and topcoating.
Note: It is important to read and understand the MSDS, process specification, and technical data sheet before working with these products.
Immediately before applying sealant to primed substrates, the surfaces should be cleaned with a solvent i.e., Desoclean® 110. Contaminants such as dirt, grease, and/or processing lubricants must be removed to insure good adhesion prior to sealant application.
A progressive cleaning procedure should be employed using the appropriate solvents and new lint free cloth (reclaimed solvents or tissue paper cannot be used). Always pour solvent on the cloth to avoid contaminating the solvent supply. Wash one small area at a time. It is important that the surface is dried with a second clean cloth prior to the solvent evaporating to prevent the redeposition of contaminants on the substrate. Substrate composition can vary greatly. This can affect sealant adhesion. It is recommended that adhesion characteristics to a specific substrate be determined prior to application of sealant on production parts or assemblies.
Special notes: For integral fuel tank repair where fresh sealant will be applied over aged fuel soaked sealant, the use of an adhesion promoter like PR-148 or PR-182 is essential.
If a Polythioether is to be applied over a polysulfide, either PR-186 or PR-1826 AP must be used at the sealant interface.
For a more thorough discussion of proper surface preparation, please consult the SAE Aerospace Information Report AIR 4069. This document is available through SAE, 400 Commonwealth Avenue, Warrendale, PA 15096-0001.
PRC-DeSoto International Sealants are generally available in three different package configurations:
Proper mixing and correct component proportions are extremely important to assure optimal results.
Two-part can kits
Note: Slow mixing by hand is recommended. A high speed mechanical mixer should not be used as internal heat will be generated reducing application life and introducing air in mixture.
Injection style Semkit® package
Note: Use even pressure; do not use force, tap, pound, or jolt ramrod if piston does not break loose readily.
Note: It may be desired to use a Semco® mixer model 388 for mixing sealants packaged in cartridges. Mixer does not reduce the number of strokes required for complete mixing, it does allow the material to be mixed easier and faster.
Two-part kits and Semkit® package
Sealants should be stored according to the instructions on the container.
Premixed and frozen (PMF)
Polysulfide sealants in a PMF form should be stored in a freezer at –40°F (-40°C) or below for optimal retention of application properties and shelf life.
Polythioether sealants require extreme low temperature refrigeration at –80°F (-62°C), or below for optimal retention of application properties and shelf life.
Thawing of PMF can be accomplished in two ways:
Ambient Thaw: Place the PMF cartridge to be used on a bench in a vertical position. Let stand at 70-80°F (21-27°C) for approximately 30 minutes. Dry any condensation from the exterior of the cartridge prior to use.
Water Bath Thaw: Place the PMF cartridge upright in a 120°F (49°C) water bath for approximately 4-6 minutes. Upon removal from the bath, carefully dry the exterior of the cartridge before using.
Application life and cure times are dependent upon ambient environmental conditions. Increases in temperature will shorten application and cure time. Conversely, lower temperatures will increase application life and cure time.
Manganese dioxide cured polysulfides: relative humidity affects the cure rate. Low humidity increases tack free and cure times. High humidity accelerates or shortens the cure time for manganese dioxide cured polysulfides.
Cure may be hastened by applying heat. Polysulfide sealants with a two hour, or less, application time, can obtain a serviceable cure hardness of 30 Durometer A after eight hours at 125±5°F (52±3°C).
Although polysulfide sealants develop a high state of cure in 14 days at 75°F (25°C), longer cure times further improve ultimate resistance to fluids, heat, and pressure. Maximum cure is usually obtained in 30 to 50 days.
Cleaning of application equipment
Wash equipment with a non-chlorinated solvent immediately after use or before sealant cures. Use commercial stripping compounds to remove cured sealant.
Health and safety
Before using a product, read and understand the Material Safety Data Sheet (MSDS), which provides information on health, physical and environmental hazards, handling precautions and first aid recommendations. Avoid overexposure. Obtain medical care in case of extreme overexposure.