Chemistry: analytical and immunological testing – Optical result – With reagent in absorbent or bibulous substrate
Reexamination Certificate
1999-05-28
2003-06-10
Alexander, Lyle A. (Department: 1743)
Chemistry: analytical and immunological testing
Optical result
With reagent in absorbent or bibulous substrate
C436S167000, C436S039000, C422S051000, C422S067000, C422S105000, C422S105000, C422S086000
Reexamination Certificate
active
06576473
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a simple field installable/removable moisture and/or acid indicator or test kit, and more particularly, to a moisture and/or acid test indicator or test kit used in a vapor compression system and the like which can be attached to the system via an existing Schrader-type service valve making the indicator easily installed and/or replaced in the field, without the need to isolate a section of the system, recover the trapped refrigerant, install the indicator into the system, and recharge the section previously isolated and evacuated. The indicating material substance or formulation of the present invention is held in a transparent fixture which when tightened on the service valve, automatically depresses the Schrader valve core allowing refrigerant to contact the indicator material. This indicator can also be configured to magnify the section of the device which contains the indicator material. This allows technicians in the field to easily, simply, quickly and inexpensively attach a moisture or test kit, or change the test kit, on a fully charged and operating system without the need to interrupt operation of the system.
The presence of moisture in the refrigerant of vapor compression refrigerators, heat pumps, and air conditioners (generally referred to as, the system) can lead to the formation of ice crystals in the throttling device, thereby restricting the flow of refrigerant and decreasing capacity. The presence of water in such a system also accelerates the formation of acids in the system which severely shorten the life of both the compressor and the refrigerant.
All systems typically have service valves with valve core depressors (often referred to as Schrader-valves). These valves, like automobile tire-valves, are opened when a valve core is depressed, usually by the device being attached to the valve. For refrigeration systems, these types of service valves with valve core depressors are used in several standard sizes, with ¼″ being the most common and ⅜″, ½″, and and ⅝″ also used.
Checking the system for moisture is a common maintenance procedure. Due to cost cutting measures, however, many systems do not contain a traditional moisture indicator in the system. When such a moisture indicator is inherent in the system it is typically located in the liquid line or in the liquid receiver as part of a liquid sight glass. Such indicators are configured for liquid refrigerant to flow through the device. Alternatively, U.S. Pat. Nos. 4,923,806 and 5,071,768, disclose a device which attaches to the service valve and allows refrigerant to flow through the device and into the ambient surroundings, indicating both moisture and acid as the refrigerant is vented to the environment. In addition to the obvious disadvantage of venting refrigerant into the environment, this device can not be installed for extended periods due to the constant flow of refrigerant being vented.
Visual sensors or indicators for use in detecting the moisture of a refrigerant in a vapor compression system are known, as seen for example, in U.S. Pat. No. 4,018,061 as well as in commercial products. A permanently installed sensor has a sight glass or window through which moisture content is determined by viewing a color-change indicator. Cobaltous chloride and cobaltous bromide are well known in the art as a moisture indicating chemicals, with the former changing from blue to pink when wet and the latter changing from green to yellow when wet.
Visual sensors or indicators for use in detecting the corrosive state of a fluid in a heat exchanger system are known as seen, for example, in U.S. Pat. No. 5,127,433. A permanently installed sensor has a sight glass or window through which corrosiveness or moisture content is determined by viewing a flap or ball displaying a color indicating either the need to change the fluid or to add corrosion inhibitors. Alternatively, corrosiveness can be indicated by a ruptured or broken diaphragm located between the sight glass and the fluid.
Humidity and corrosion indicators for packaged goods in which a thin cobaltous chloride film is used as the sensing element are discussed in U.S. Pat. No. 3,084,658. An elastomeric grommet sealed by a transparent disk is inserted into an opening in a package wall. A disk impregnated with the cobaltous chloride is secured beneath a window and can be replaced.
With respect to closed refrigeration systems, other types of indicator systems are known for testing the presence and concentration of contaminants in a refrigerant. For example, U.S. Pat. Nos. 4,923,806 and 5,071,768 show apparatus for testing liquid or vapor contaminants in a closed system regardless of whether or not the apparatus is operating. A disposable testing tube made of transparent material is used at the end of a compressor discharge line or elsewhere in the system. One section of the tube is provided with water removal and moisture indicating chemicals, such as cobaltous chloride and another section is provided with acid indicating chemicals such as a solution of bromophenol blue, ethanol and glycerol. This known construction is relatively complicated and requires a separate, specially configured flow restrictor in addition to a tube holder, and an expensive testing tube in which the multiple contaminant testing chemicals and filter screens are permanently located. U.S. Pat. No. 4,018,061 describes a moisture-indicating device in contact with flowing liquid refrigerant. This device is an integral part of the refrigeration system, and as such, the system must be shut down in order to install the device.
Likewise, U.S. Pat. No. 5,377,496 shows an acid contamination indicator for closed loop vapor compression refrigeration systems in which the indicator is permanently or removably installed in the bypass line around the system compressor where the refrigerant is always in the gaseous phase. A casing has a visual indicator bed of bromophenol blue as the acid indicating medium which is contacted by the refrigerant after flowing through a filter and a flow restrictor orifice. Porous retainer disks are held against the bed by springs. Moreover, the indicator, which changes color when exposed to acids or bases, are solid, and they must be exposed to the test stream in some fashion. Accordingly, this solid indicator must be mixed with an inert substance to provide some porosity, contact surface area, and increased volume and then packaged in a clear tube. The vapor refrigerant is then passed through the porous mixture arranged in a bypass loop between the suction and discharge ends of a compressor or in the main refrigerant flow path between the compressor discharge and a heat exchanger to observe a color change. Again, we have recognized that this is an unduly complicated construction which requires a substantial outlay for production and installation. A bypass of refrigerant from the compressor discharge to the compressor suction reduces the capacity and performance of the vapor compression system as well as increases the compressor operating temperature since hot discharge vapor is reintroduced into the compressor suction.
Pending U.S. patent application Ser. No. 08/423,211, filed Apr. 17, 1995, assigned to Mainstream Engineering Corporation of Rockledge, Fla. discloses yet another way of detecting the presence of acid in a refrigeration system, with an indicating device configured to temporally flow refrigerant through it and vent this refrigerant to the environment. The disclosure of that application is incorporated by reference herein.
Yet another type of contaminant detector is marketed by Refrigeration Technologies of Fullerton, Calif. under the trademark “CHECKMATE”. A specific volume of gas passes through a detection tube at a predetermined termination pressure. However, a sealed Pyrex detection tube containing a color-changing chemical and having ends which are pierced when fully assembled can only be used once even when the test is negative, and thus this app
Back Dwight D.
Cole Gregory S.
Grzyll Lawrence R.
Meyer John A.
Scaringe Robert P.
Alexander Lyle A.
Crowell & Moring LLP
Mainstream Engineering Corporation
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