THE DAYTON CLEANER
The Dayton Process is a "fluoride-ion" cleaning system which introduces hydrogen gas into an otherwise completely enclosed retort. It generates HF by heating the inert fluorocarbon powder ptfe in hydrogen until it decomposes into the momomer gas tetrafluoroethylene and then reacts to form HF and methane gases. The rate of decomposition can be controlled accurately by controlling the heat input and the hydrogen flow.
A measured quantity of ptfe is placed in the retort along with the parts to be cleaned.
The heating cycle and gas cycles are all under control of mass flow controllers and a micro processor. Fail safe systems will shut down the process in the event of any fault condition arising. The retort is then isolated and it is the nature of the process that under these conditions the reactions inside the retort ceases, leaving it in a safe condition.
The following equipment is required
The Dayton Process offers a safe cost-effective method of fluoride-ion cleaning which is approved by Rolls-Royce and Pratt & Whitney for braze repairs and is acceptable to health/environmental authorities.
The process offers fluoride-ion cycles for different purposes. Extensions to the process for use in stripping of coatings are developed and a full technical backup service is available.
1) Retort/Scrubber
The cylindrical retort has a flange at the top with an ‘o’ ring seal. The lid assembly carries the parts racks, scrubber tank and the gas and thermocouple quick release couplings. There are also water connections to supply cooling for the ‘o’ ring seal.
2) Furnace and Cooling Station
An electrically-heating furnace which can be floor mounted or sunk into the floor, to achieve convenient height for access to the flange and connections. A cooling station fitted with forced draft extraction gives rapid cooling of the retort.
3) Utility Station
Gas lines and the other connections are run overhead from a central utility station. Hydrogen, argon, air for operating valves and water for cooling are supplied from this station. The station houses the massflow controllers and solenoids for all lines to be activated by the controller, and it contains pressure switches that interrupt the process in the event of reversed pressure drop on the scrubber (protection against vacuum), too high a pressure (indication of system clog), and too little water pressure for cooling. Retort exhaust gases are vented to atmosphere. Thermocouple lines from the controller to the retort are also routed through the utility station. One bundle of lines connects the process retort/scrubber and furnace to the controller/utility station combination. The station avoids the problem of gases inside the electronic control cabinet and houses high/low alarm flow meters on the hydrogen and argon lines.
4) Control Console
A programmable controller and operator console are linked to the utility station. This console monitors all flow parameters and thermocouple lines and handles all the system fail safe features. The console contains a chart recorder, warning bell and panel lights to guide the operator during the operating sequence.
5) Models
Choose from models that include:
Model DP-101 will clean up to 11 ft2 (1 m2) of component surface area in a single process cycle.
Model DP-102 will clean up to 33 ft2 (3 m2) of component surface area in a single process cycle.
Model DP-103 will clean up to 54 ft2 (5 m2) of component surface area in a single process cycle.
Seven reasons why you should consider the Dayton Process BV Fluoride Ion Cleaning System:
- Gaseous cleaning of service-exposed turbine engine components (blades, vanes, casings, etc.) is considered the best approach to preparing these parts for repair by brazing or welding.
- An effective halide cleaning unit is an essential prerequisite to the successful braze repair of turbine components from modern aviation gas turbine engines.
- Of all the known cleaning processes and systems currently available, the Fluorocarbon Cleaning Process (FCP) is the most effective, most reliable and most attractive from health, safety and environmental aspects.
- The FCP is a unique ‘dry' process which completely eliminates the problem of Inter Granular Attack (IGA).
- It is the most effective process for the removal of surface and sub-cutaneous complex stable metal oxides from cracks, and free surfaces of nickel- and cobalt-based superalloy engine run components.
- Controlled surface depletion of strong oxide forming elements like aluminum and titanium, actively promotes good braze wetting and infill of even the most complex superalloys.
- This unique combination of cleaning and surface conditioning without IGA, makes the DAYTON FCP an ideal enabling process for the braze repair of today's generation of engine run superalloy turbine components.
