Heat exchange – With timer – programmer – time delay – or condition responsive... – Vent of system
Reexamination Certificate
1996-10-11
2001-01-16
Ford, John K. (Department: 3743)
Heat exchange
With timer, programmer, time delay, or condition responsive...
Vent of system
C165S281000, C165S150000, C138S027000, C137S071000, C137S068230, C285S201000, C285S141100, C220S203080
Reexamination Certificate
active
06173767
ABSTRACT:
FIELD OF THE INVENTION
The present invention is directed to a pressure relief device and, in particular, to a replaceable pressure relief device for use with heating and cooling coils.
PRIOR ART
Heating and cooling coils are well known for use in heat-exchange devices for cooling and/or heating. Such coils typically have a heat transfer fluid circulating therethrough to accept or dissipate heat. It can be appreciated that these coils may face temperature extremes and that the fluids in the coils may also face temperature highs and lows having a great differential. At extremely low temperatures, the problems encountered are especially troublesome, as fluids may freeze. Heat exchange fluids may also expand at high temperatures or otherwise cause pressure buildups in the coils. The pressure buildup may cause the coils to burst, causing irreparable harm and leading to replacement of the coils. This work is costly and requires labor intensive, in the field repairs.
To prevent pressure buildups and damage to the coils, freeze plugs and various other devices have been conceived for preventing coils from bursting. However, such devices typically are not easily installed or require expensive and complex procedures for the replacement of plugs and other pressure relief devices. In addition, the delicate nature of copper coils cannot easily support plugs so that removal of freeze plugs, which become corroded in place over time, may be difficult or impossible to accomplish, as the copper tubing may be crushed or punctured when gripped by a wrench or pliers. Should it be necessary to grip the tubing with a wrench or other tool to reset the pressure relief device, the delicate nature of copper tubing may lead to damaged coils. This defeats the objectives of the pressure relief device and may cause even greater damage to the heating and cooling coils. Another problem encountered with pressure relief devices for heating and cooling coils is a lack of space. Coils are often spaced closely together, making access to removable pressure relief devices very difficult or impossible if the pressure relief devices are too wide.
In addition to not adequately preventing damage, pressure relief devices may not provide a consistent and/or predictable pressure relief point. Therefore, it may be possible that the relief pressure occurs at different pressures at different points in the coil. These devices' lack of predictable and consistent burst pressures makes designing an optimum pressure relief device nearly impossible. The relief pressures are critical when thin walled copper tubing coil is used, as the relief pressure may be very close to the pressure which may damage the coil. With these designs, only some pressure relief devices may function properly so that it may be necessary to replace portions of the coil near pressure relief devices that do not burst at the desired pressure and allow damage to the coils.
It can be seen then that a new, improved pressure relief device is required for heating and cooling coils. Such a device should provide a simple and quick method of replacement should the pressure relief device be activated. Such a device should provide consistent and predictable pressure rupturing points so that the relief device is activated at the optimum pressure to protect the coil. In addition, such a device should be easily and cheaply manufactured and be sufficiently narrow to be easily installed while providing support points for tools in addition to the copper coil. The present invention addresses these as well as other problems associated with providing pressure relief for heating and cooling coils.
SUMMARY OF THE INVENTION
The present invention is directed to a pressure relief device and in particular, to a pressure relief device for heating and cooling coils which have a fluid circulated therethrough. Cooling coils often have pressure buildups due to freezing, fluid expansion and/or other complications. The coils often burst due to the increased pressure, requiring repair and/or replacement. The copper tubing typically used for such coils is difficult to grasp and handle without further damaging the coil. Therefore, pressure relief devices are utilized to eliminate damage and to decrease the equipment down time due to coil damage caused by pressure buildups.
According to the present invention, the pressure relief device has a mounting base attaching to a bend or header of the coil. The mounting base provides support for the pressure relief device. A cover removably attaches to the base and is tightenably connected thereto. In a first embodiment, the base includes an orifice extending therethrough to the interior of the coil. In this manner, pressure may be communicated through the coil and to the cover. Intermediate the cover and the base is held a rupturable membrane or diaphragm. The diaphragm is part of a strip which may be advanced to a usable portion when the diaphragm has been ruptured. With this configuration, upon rupturing, the diaphragm sheet may simply be advanced over the base to repair the coil. The cover attaches to the base with bolts on either side of the orifice. In addition, an o-ring or other gasket may be utilized with the base to provide a seal with the diaphragm strip.
The delicate nature of the coils and the damage which may occur is prevented by having a base which can be gripped with tools for removing and replacing the diaphragm strip. It can be appreciated that with the present invention, safe, inexpensive and quick repair can be easily accomplished when pressure buildups occur.
A second embodiment of the present invention includes a threadably connected cover which attaches to a base portion on a bend or header of the coil. A hex head or other tool grippable portion is permanently attached to the header below the threaded portion. A removable cover includes an upper portion having a diaphragm which ruptures upon interior coil pressure reaching a predetermined level. The cover includes a tool grippable portion so that a pair of wrenches, for example, may be used to grip the portion on the coil and remove the ruptured cover.
These and various other advantages and features of novelty which characterize the invention are pointed out with particularity in the claims annexed hereto and forming a part hereof. However, for a better understanding of the invention, its advantages, and the objects obtained by its use, reference should be made to the drawings which form a further part hereof, and to the accompanying descriptive matter, in which there is illustrated and described a preferred embodiment of the invention.
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Ford John K.
Merchant & Gould P,C,
SGCM Partnership, L.P.
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