Serec's patented high vacuum, airless vapor degreasing technology utilizes organic solvents to clean metal parts in a unique process. Though this process shares some commonality with traditional vapor degreasing systems, there is one major difference; the solvent is never mixed with air, so emissions are low.
The Serec philosophy is founded in pollution prevention , not end-of-the-pipe pollution control. Traditional vapor degreasing takes place in open air. Since the presence of air neither enhances nor detracts from cleaning effectiveness, the air contamination which takes place during open-air degreasing is n eedless. By removing the air before introducing the cleaning solvent, the contamination problem is eliminated with no loss of cleaning effectiveness.
TYPICAL OPERATING CYCLE
The chamber is loaded with items to be cleaned. Once the door is closed and sealed, the air is evacuated from the degreasing chamber via a vacuum pump. A pressure of less than 5 torr is typically achieved (1 torr = 1 mmHg).
When the desired vacuum is achieved, solvent and vapor is released from the vapor supply tank into the degreasing chamber. The solvent and vapors then adhere as liquid to the surfaces of the parts to be cleaned, producing the desired cleaning action.
During cleaning, condensation will heat the parts being cleaned. To cool the parts and to rinse deposits aft er cleaning, the parts are sprayed or soaked with liquid solvent from the clean solvent tank. The cleaning and spraying cycle can be repeated for the number of times and duration initially selected by the operator. When the cleaning, spraying or soaking cycles are complete, the vapor recovery process begins.
Both the vapor and liquid solvent are removed from the degreasing chamber during the vapor recovery process. The hot solvent vapor is moved from the degreasing chamber via a vacuum pump to a heat exchanger, where it is condensed. From the condenser it is returned to the solvent holding tank. The liquid is drained from the bottom of the chamber to the vapor supply tank. As the pressure continues to decrease, the liquid solvent on the warm surfaces flash to a vapor and are removed via the vacuum pump.
To remove any remaining solvent, the degreasing chamber is restored to atmospheric pressure. The air/solvent mixture is evacuated from the chamber through a carbon filter (where necessary). Finally, with the chamber at atmospheric pressure again, the operator can open the door and remove clean, dry parts.
The amount of solvent remaining in the chamber is well below the EPA guidelines for momentary exposure. Since there is no release, there is also no solvent odor.
Figure 1 - 1 . Schematic of a Typical Vacuum Vapor Degreasing System
The dirty solvent in the vapor supply tank is distilled to remove contaminates. This occurs in two distinct modes:
Short distillations occur automatically during the cleaning cycle, when the pumps are available.
Deliberate distillation should also occur periodically, as an operator - selected process. This process distills all of the system's solvent and is operator controlled. The frequency of this process is directly related to the contaminant introduction rate which can be highly variable. Each customer must determine by operating experience the frequency of distillation based upon their own requirements.
During distillation, the solvent is heated and the escaping vapors are collected and condensed. The clean solvent is returned to the solvent holding tank. The contaminants that remain in the distillation chamber must be removed through the access port when the auto - distill cycle is complete.