TASK 70-21-02-110-002
1 . General.
NOTE:
Unless specified differently, the procedures that follow are considered equivalent alternatives to this process for appropriate sized metallic parts:
TASK 70-21-03-160-001, Cleaning Method No. 3 - Steam Cleaning, if a water break free surface can be obtained.
TASK 70-21-22-110-042, Cleaning Method No. 22 Light Duty Aqueous Cleaning (Method 1).
TASK 70-21-22-110-050, Cleaning Method No. 22 Light Duty Aqueous Cleaning (Method 2).
Method 22 can also be used before NDT inspections.
CAUTION:
DO NOT APPLY THE PROCESS TO TITANIUM ALLOY PARTS, TO BALL BEARINGS, OR TO RUBBER OR PLASTIC PARTS. THESE MATERIALS REACT TO CHLORINATED HYDROCARBONS OR ARE DESTROYED BY THE TEMPERATURE OF VAPORS.
CAUTION:
DO NOT INTRODUCE MOIST PARTS IN THE SOLVENT FUMES. THE PRESENCE OF WATER IN THE BATH REDUCES ITS EFFICIENCY AND CAUSES THE ACIDIFICATION OF THE PRODUCT.
A.Vapor degreasing is used to remove greasy substances. The continuous distillation means the parts are only in contact with clean solvent, thereby improving the degreasing efficiency and speed. The condensation of the solvent vapor on the parts during the initial phase also promotes the dissolution of greases and oils.
B.After condensation stops, a spray of cold solvent may be used. The spray bar must operate below the vapor level and avoid excessive turbulence which may cause vapor in the tank to escape.
C.Alternative solvent materials can be used in the vapor degreasing process. The operating procedures used for each solvent must reflect the boiling points of the solvent and the process control concerns stated in this procedure, including solvent concentrations and solvent tank maintenance per the recommendations of the original equipment manufacturer and the solvent manufacturer.
2 . Equipment.
Subtask 70-21-02-110-021
D.The following equipment is required for application of this process.
(1)A disposal method for used or spent solvent that follows all local and governmental laws and regulations.
(2)It is recommended that adequate ventilation be provided so solvent vapors that escape from the vapor degreasing station are not released directly into the atmosphere. Do not place fans or other exhaust ventilation systems above, below, or anywhere near the vapor degreasing station. Do not place the vapor degreasing station near open windows, near doorways, or in a draft.
(3)The vapor degreasing station shall include:
(a)A solvent tank, whose accessories in contact with the solvent must be of a compatible material so they will not degrade the parts going through the vapor degreasing process.
(b)A heating coil in the tank capable of heating the solution to the boiling point of the solvent and maintaining the manufacturer's recommended vapor degreasing temperature.
(c)Cooling must be supplied in sufficient amount to provide for adequate cooling of vapor in the condensation zone. The system should provide a means to prevent the solvent vapors from escaping into the atmosphere.
3 . Materials.
Subtask 70-21-02-110-022
WARNING:
FOLLOW ALL THE ENVIRONMENTAL HEALTH AND SAFETY REQUIREMENTS ON THE MATERIAL SAFETY DATA SHEET FOR THE SOLVENT BEING USED.
E.Only approved solvents can be used in the vapor degreasing process. If a solvent is not in TASK 70-80-04-800-801, Consumable Products - Cleaning Compounds and Solvents, you must have documentation of testing at an independent laboratory that shows acceptable performance per:
SAE ARP1755, Stock Loss Test, and
The hot corrosion test specified in TASK 70-16-80-700-009, Suitability Test of Temporary Marking Products.
4 . Procedure.
Subtask 70-21-02-110-023
WARNING:
SOLVENT IS TOXIC. AVOID INHALATION OF VAPORS. AVOID PROLONGED CONTACT WITH EYES, SKIN, OR CLOTHING. OPERATOR SHOULD USE ONLY IN WELL VENTILATED AREA.
F.Slowly immerse the parts in the tank until they are below the condensation level of vapors. The tank must be maintained at the specified temperature per the solvent manufacturer's recommendations.
G.Spray the parts with a jet (atomized or not) of cold solvent (optional step).
H.Hold the parts in this position until the solvent evaporates off of the part (optional step), or at least until the condensation stops (required step).
I.Raise the parts slowly above the condensation level to permit drying and evaporation of the solvent. Drain any liquid solvent entrapped in cavities.
J.Steps A, B, C, and D above may be repeated with the part in various positions, particularly for parts having intricate shapes.
CAUTION:
WEAR CLEAN GLOVES TO HANDLE DEGREASED PARTS. THIS AVOIDS SUBSEQUENT OXIDATION.
K.Remove the parts from the degreasing tank.
L.Dry the parts using clean, dry air.
5 . Quality Assurance.
Subtask 70-21-02-110-024
M.Verify that all of the initial contamination has been eliminated and that no local build-up of contaminants has occurred during drainage and drying.
N.Ensure that periodic checks are made of acidity and oil content of solution per the solvent manufacturer's recommendation.