Locks – Special application – For control and machine elements
Reexamination Certificate
1999-09-14
2001-03-27
Gall, Lloyd A. (Department: 3627)
Locks
Special application
For control and machine elements
C070S178000, C070S221000, C070S422000, C070S424000, C070S455000
Reexamination Certificate
active
06205826
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention (Technical Field)
The present invention relates to safety devices for preventing tampering or accidental change of the manually set position of a rotatable shaft, such as the shaft on a valve or regulator that controls the flow of fluid.
2. Background Art
Present lockout devices are designed to lock the handle on a valve or regulator where the handle is part of the original valve or regulator supplied by the manufacturer. Typically in these lockout devices, an enclosure is formed around the handle with a padlock that locks the enclosure in place to prevent access to the handle thus preventing the rotational position setting of the handle from being altered either accidentally or out of ignorance or maliciousness. Other lockout devices show a lock assembly that is housed within a cast valve body that with the aid of a key controls rotation of the valve shaft.
Examples of such locks are shown in U.S. Pat. Nos. 440,714 (Lamb), 441,357 (Crowell), 1,154,389 (Fogalsong), 1,248,204 (Thomsen), 1,250,127 (Beers), 1,380,675 (Myers), 1,526,047 (Butterworth), 1,672,137 (Seng), 1,843,072 (Stone), 2,795,129 (Schoepe), 3,134,291 (Barry), 5,085,063 (Van Dyke). Additional patents were cited in the prosecution of the parent application from which this application is a continuation-in-part.
The principal objection to all of the above-identified lockout devices is the complexity of the mechanism which causes problems in reliability, increased manufacturing cost, and thus an increased price. Furthermore, many of these lockout devices require that the valve or regulator body handle be specially cast so as to house the locking assembly. Accordingly, the locking device is part of the valve or regulator when purchased and each valve or regulator manufacturer may have different types of devices which prevents uniformity of a single lockout device used throughout a manufacturing plant. It would be highly desirable to have a lockout device that could be used for a wide variety of different manufacturers' valves or regulators so that plant personnel could be taught to operate a single type of lockout device even though valves and regulators from different manufacturers are used in the same industrial plant.
Additionally, the prior art does not address the problem posed to industrial plant managers attempting to comply with regulations of the Occupational Safety and Health Act (OSHA). In particular, in 29 C.F.R. § 1910.147, the regulations set forth the responsibility of a plant operator for the control of hazardous energy. These devices are typically referred to as “lockout/tagout” devices. The purpose, as set forth in the regulations, is to prevent the “unexpected energization or start-up of the machines or equipment, or release of stored energy that could cause injury to employees undertaking servicing and maintenance of machines and equipment in the plant.” According to the regulations, “lockout” requires the “placement of a lockout device on an energy-isolating device, in accordance with an established procedure, insuring that the energy-isolating device and the equipment being controlled cannot be operated until the lockout device is removed.” Such safety lockout device requires some personnel-controlled means for locking, such as a key- or combination-operated lock. The regulation further provides that safety lockout devices shall be standardized within the facility with respect to color, shape, or size.
An important feature of the safety lockout procedure is that the safety lockout device must be under the exclusive control of the authorized employee performing the servicing or maintenance. Accordingly, it is understood that compliance with these regulations will require that a safety lockout device has at least one key, or combination, that can be used only by the authorized service / maintenance person to override any other lockout device that otherwise may be applied to the energy-controlling device.
If it is desirable to have a lockout device to maintain a rotatable shaft in a fixed manual setting, during normal operation of the plant, there may be provided an “operations” lockout device that is available to the process control engineer, supervisor, or other employee responsible for establishing the settings on all energy-controlling devices. The OSHA or “service/maintenance” or “safety” or “personal” lockout device then must supercede this operations lockout device so that a second key or combination lock under the exclusive control of service personnel can be applied to prevent access to the operations lockout device.
SUMMARY OF THE INVENTION
The present invention comprises a lockout device for a rotating shaft, such as the shaft that controls the position or setting of a valve or regulator, to prevent any unauthorized personnel from changing the setting of the rotatable shaft due to a lack of knowledge as to why the shaft is set at a particular position, to prevent inadvertent rotation of the shaft to a new setting, or to prevent malicious resetting of the shaft to thereby change the flow of energy through the valve or regulator. In one embodiment, the lockout device includes a handle that may be attached to a drive stem of a variety of various manufacturers' valves, regulators, etc., a gear or sprocket fixedly mounted on the drive stem within the handle body and a key lock mechanism selectably positioned in the handle body to engage or disengage the gear and thereby prevent rotational movement of the gear and the rotatable shaft in either direction from the selected setting.
In another embodiment, the lockout device includes a gear that has specially shaped indentations between adjacent teeth so as to form a ratchet gear that is engageable by the key lock mechanism or, alternatively, a spring-actuated pawl that will allow the handle and the rotatable shaft to be operated in either the clockwise or counterclockwise direction, but not both. This permits the lockout device, when in the locked position, to allow the shaft to be rotated only in one direction, such as to close the energy control device, but not to open it further than the original setting.
In another embodiment of the lockout device, there is additionally provided a safety or personal lockout device comprising a cap which may be locked in position on the handle through the use of one or more second key lock mechanisms such that the cap overlies the first lockout device whereby the safety lockout device has exclusive control of the position of the energy control device.
Additional embodiments of a safety lockout device include a cap which may be locked in position on the handle so as to prevent access to the first key lock mechanism through the use of a scissors-like bail which may be locked when in a closed position by one or more ordinary padlocks wherein the padlock key provides exclusive personal control over access to the first key lock mechanism.
A primary object of the present invention is to provide a simple, low-cost, highly reliable, compact, lockout device for use on a wide variety of rotatable shaft control devices, such as valves, regulators and the like.
Another object of the present invention is to provide a lockout device which when in the locked position will still allow the rotatable shaft to be rotated in one direction only, such as to close the setting of the shaft of the control device but not to allow opening of the control device.
Still another advantage of the present invention is to provide a lockout device that complies with the Occupational Safety and Health Administration requirements for plant safety.
Still one more object of the present invention is to provide a lockout device having two lockout mechanisms; the first mechanism being in the control of plant personnel responsible for the operation of the process including the setting of various valves, regulators, and other energy-controlling devices having a rotatable shaft wherein the operations lockout device includes a key lock mechanism with a key (or combination) available only to op
Gall Lloyd A.
Neelchine Engineering, Inc.
Peacock Deborah A.
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