US3500682A

US3500682A - Apparatus for weathering coated test panels

Info

Publication number: US3500682A
Application number: US734751A
Authority: US
Inventors: Stephen E Newfield
Original assignee: STEPHEN E NEWFIELD
Current assignee: STEPHEN E NEWFIELD
Priority date: 1968-06-05
Filing date: 1968-06-05
Publication date: 1970-03-17
Anticipated expiration: 1987-03-17

Description

INVENTOR. sr PH? E. NEWFIELD A TORNEYS S. E NEWFIELD Filed June 5, 1968 APPARATUS FOR WEATHERING COATED TEST PANELS March 17, 1970 United States Patent 3,500,682 APPARATUS FOR WEATHERING COATED TEST PANELS Stephen E. Newfield, 4309 Fairway, Los Alamos, N. Mex. 87544 Filed June 5, 1968, Ser. No. 734,751 Int. Cl. G01n 17/00 US. Cl. 73-150 7 Claims ABSTRACT OF THE DISCLOSURE Panels coated with a protective, anti-corrosive material to be tested are mounted in the top portion of a cabinet which also contains a plurality of fluorescent lamps and a reservoir filled with Water. The water is heated to fill the container with a water vapor and the fluorescent lamps energized to radiate ultra-violet light onto the test surfaces of the panels. By separately controlling humidity and radiation, weathering is substantially accelerated and environmental conditions of use can be approximated.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

BACKGROUND OF THE INVENTION The present invention relates to test apparatus and, in particular, to apparatus for weathering panels coated with anti-corrosive protective coatings.

Several accelerated weathering devices presently are in use, the principal ones being the weatherometer and the salt spray cabinet. Most weatherometers essentially are variations on one general arrangement in which the test panels are placed on the inside of a large drum which rotates about an ultra-violet light source disposed in the center. The source may be a carbon are or a xenon lamp, the panels also being rotated through a section in which they are wetted by a water spray. Such an arrangement appears to be seriously limited in its ability to provide a corrosive environment and in addition it requires extensive maintenance, such as the changing of carbons, etc. The apparatus also is relatively expensive, requires high power sources and special plumbing attachments for its supply of de-ionized water.

The salt spray type of accelerated weathering apparatus utilizes a corrosive environment of moisture and salt, these devices being closed chambers utilizing an atomizer to introduce the salt solution as a fine mist. Aside from the fact that sunlight is not simulated, these arrangements also require extensive maintenance to replenish the salt solutions and to charge the units with compressed air.

OBJECTS OF THE INVENTION It is therefore a principal object of the present invention to provide Weathering apparatus capable of significantly accelerating the weathering effects, the apparatus being relatively small, inexpensive, and easily maintained.

Other objects and their attendant advantages will be considered in the detailed description which is to follow.

SUMMARY OF THE INVENTION The objects of the invention are achieved by employing a cabinet preferably formed of anti-corrosive material, the cabinet being provided in its upper portion with means for mounting the test panels. A reservoir is formed in the lower portions of the cabinet and heater means provided to heat the water contained in the reservoir. When heated, a water vapor fills the cabinet and, due to the temperature gradient between the interior and the exterior of the cabi- 3,500,682 Patented Mar. 17, 1970 net, the water vapor condenses on all interior surfaces, including the test panels. An elongate ultra-violet light source, such as several fluorescent lamps, extend from one end of the cabinet to the other medially of the cabinet. Preferably, the arrangement of the fluorescent lamps is such that radiation from these lamps is evenly distributed over the test surface areas of the panels. Cycle control means permits the light and the heat to be regulated in any desired manner. For example, conditions can be established for promoting maximum weathering acceleration, or, if desired, the controls can be regulated as to simulate the particular environmental conditions anticipated in the use of the coatings.

BRIEF DESCRIPTION OF THE DRAWING A preferred embodiment of the invention is illustrated in the single figure of the accompanying drawing which is a somewhat schematic perspective view of the cabinet and its incorporated components.

DESCRIPTION OF THE PREFERRED EMBODIMENT The operative elements of the invention are contained in or mounted on cabinet 1 formed of side walls 2, end walls 3, a bottom wall 4, and a top which, as may be seen in the drawing, is formed of a center beam 6 supported by end walls 3 and by abbreviated canted ledge portions 7. Panels 8, which are in the form of rectangular plates, are mounted side by side to complete the formation of the top wall and to provide an enclosed container structure. Preferably, the panels are supported by ridges 9 providing an abutment against which the panels rest.

As already indicated, the principal function of the cabinet is to permit an accelerated weathering of test panels which have been coated with a protective coating to be tested. Particularly coaings would be the various anticorrosive pains to be used on ships or in other corrosive environments. For test purposes, one surface of the panels is coated with the material and the panels then positioned on the container so that the coating surfaces face inwardly.

Accelerated weathering is accomplished by exposing the test panels to ultra-violet light and to moisture. The moisture is derived from a supply of water 11 contained in a reservoir portion of container 12, this portion being formed principally by bottom wall 4 of the cabinet. Beneath reservoir 12 is a heating unit 13 which, most suitably, utilizes a coil heater to raise the water temperature sufficiently to cause the interior of the container to become filled with a water vapor. The moisture for the test panels is supplied by the water vapor which condenses on the test panels due to the temperature gradient between the interior of the casing and its exterior.

Weathering also includes exposing the test panels to an ultra-violet light source that simulates natural sunlight, the source being three fluorescent lamps 14 mounted in a triangular arrangement in end Walls 3 so that the lamps extend throughout the length of the container from one end to the other. It is most desirable to provide an even distribution of the ultra-violet radiation and to achieve such a distribution, the triangular arrangement of the lamps matches the triangular shape of the top of the container.

Both the fluorescent lamps and the heater are electrically energized through a power line 16 provided with a plug by means of which the power line can be coupled into conventional line sources. Power for the lamps is supplied through a timer switch 17, a starter and ballast unit 18 and a socket fixture 19. The fluorescent lamps most suitably are of the germicidal type capable of emitting intense ultra-violet light, such types being filled with a mercury vapor or a vapor of some other composition capable of breaking down into a self-maintainingdis charge. A variety of these lamps are available commercially. Starter and ballast unit 18 also is a commercial item customarily used with fluorescent lamps, the starter, when energized, opening to provide high voltage across the electrodes causing the vapor to break down. The ballast portion of unit 18 is employed to limit the current to a safe value since the self-maintaining discharge is not inherently self-limiting. Timer switch 17 may be any conventional available switch such as the common types operating on a clock mechanism. Its purpose is to control the light cycle by shutting ofl? line power after a predetermined time interval. The switch utilizes a settable dial 21 permitting the operator to set the light cycle according to a predetermined testing program.

Heating unit 13, which, if desired, could be an immersion type, derives power from the line source and the power is applied through another timer switch 22 having a dial 23 similar to switch 17. The circuit also includes a thermal switch 24 disposed in the interior of container 1. The thermal switch, which is commercially available in many varieties, is employed for the obvious purpose of automatically regulating the interior temperature of the system. It provides closer temperature control by automatically interrupting the power supply when a predetermined temperature has been reached.

The operation of the cabinet should be apparent from the previous description. Panels 8 initially are prepared by coating one side surface with the protective coating to be tested, and, as contemplated, this coating usually will be of an anti-corrosive nature. The panels are then placed in position to enclose the top of the cabinet and provide an enclosed structure capable of providing a temperature diflerential between the interior and exterior surfaces. Depending upon the natural conditions which the testing is intended to simulate, power then is applied to either or both the lamps and the heater. Radiation from the lamps simulates sunlight, while the vapor rising from the heated water provides the corrosion-promoting humidity by condensing on the coated surfaces of the panels. Settingpf the timers limits the application of the radiation and moisture in accordance with the test program. Obviously, no ideal program will simulate all conditions and it is for this reason that the unit is provided with its flexibility. For example, if the ships surface on which the tested coating is to be applied is a surface which rarely is exposed to direct sunlight, the operation of the fluorescent lamps can be limited or eliminated entirely.

The particular advantages of this apparatus aside from its flexibility, lies in its compactness, low expense and particularly in its ability to significantly accelerate the weathering of the panels. In use, 'such cabinets increase the weathering by a factor of about three as compared with more conventional weatherometers. Other advantages are that the apparatus avoids the need for compressed air atomizing devices and expensive plumbing arrangement and that the water providing theweathering moisture can be ordinary tap water. Such simplifications materially reduce maintenance and minimize shut-down time.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. Apparatus for promoting a controlled weathering of coated test panels, said apparatus comprising:

an anti-corrosive cabinet,

stationary means for mounting a test panel in the upper portion of said cabinet, reservoir means formed in the lower portion of the cabinet and adapted to contain a water supply, means for heating said water to produce water vapor, said test panel having an exterior surface subject to the environment outside said cabinet for inducing the formation of a condensate on a surface of said panel interiorly the cabinet, an elongate ultra-violet radiation source extending medially through said cabinet, means for energizing said radiation source, and means for separately and independently controlling the operative cycles of said radiation source energizing means and said water heating means, said panel mounting means exposing a coated surface area of said panel to said radiation and water vapor and said mounting means being arranged relative to said radiation source for prompting a uniform distribution of the radiation on said exposed surface area. 2. The apparatus of claim 1 wherein said radiation source is formed of a plurality of fluorescent lamps.

3. The apparatus of claim 2 wherein said cabinet is an elongate structure having top, bottom, side and end walls,

said top being formed with means for mounting a plurality of test panels side-by-side for providing a top enclosure for the cabinet so that one surface of each panel is subject to the environment outside said heated cabinet to induce the formation of a condens-ate on a surface of each panel inside the cabinet. 4. The apparatus of claim 3 further including starter and ballast means for said fluorescent lamps.

5. The apparatus of claim 4 wherein said radiation source energizing means and said water heating means include a power line, and

said control means includes separate timer switches electrically coupling said energizing and heating means separately to said power line. 6. The apparatus of claim 5 wherein said control means further includes thermally-responsive switch means electrically coupled between said water heating means and its timer switch,

said thermal switch being carried internally of said cabinet. 7. The apparatus of claim 5 wherein panel mounting means provides a triangular top enclosure,

said lamps being disposed in a triangular arrangement corresponding to said triangular top enclosure.

References Cited UNITED STATES PATENTS 2,434,450 l/ 1948 Williford 73150 2,804,770 9/1957 Gunther et al. 73150 3,292,418 12/ 1966 Oehme et a1 73150 X OTHER REFERENCES Circular No. 334, Painting Tests on Panels Impregnated With Zinc Chloride or Creosote, H. A. Gardner, June 1928, pp. 588-598.

Brochure, AtlasElectric Devices Co., Fade-Ometers and Weather-Ometers, 1962, pp. 4, 5, 12, 13, 16-25.

LOUIS R. PRINCE, Primary Examiner H. C. POST I11, Assistant Examiner