Fluid sprinkling – spraying – and diffusing – With system fluid relief or return to supply
Reexamination Certificate
1999-11-15
2001-01-23
Kashnikow, Andres (Department: 3752)
Fluid sprinkling, spraying, and diffusing
With system fluid relief or return to supply
C239S526000, C239S569000, C251S041000
Reexamination Certificate
active
06176439
ABSTRACT:
FILED OF THE INVENTION
The present invention relates to the field of control systems for mixing equipment, and more particularly to a new and improved emergency shutdown system and method.
BACKGROUND OF THE INVENTION
At a blast pressure of 100 psi, a grain of abrasive shooting from the mouth of a wide-throat long venturi blast nozzle hits its target at 420 miles per hour. The velocity increases to approximately 850 miles per hour —faster than the speed of sound —at 150 psi. The Occupational Health and Safety Organization (OSHA) requires a safety system on all abrasive blasting equipment as well as on other equipment. Such safety systems usually include what is referred to in the art as a “deadman's control.” A deadman's control is a device that stops the machinery when the control is released. As is well known, these controls have been implemented as mechanical, pneumatic and electric deadman controls. To insure worker safety, these deadman's controls should be reliable, safe, and activate under of a variety of predictable and unpredictable conditions, such as accidental start-up, operator error, etc.
As is well known, deadman's controls may be implemented at different locations within a system, such as an abrasive blasting system. One such implementation is to put the device which the deadman's apparatus actuates at a point in the system near the so-called mixing pot. In such an arrangement, when an operator holding a hose releases a deadman's control at or near a nozzle end, the device under its control at the mixing pot shuts flow to the hose. With such arrangement, there is typically a delay of several seconds before spray in the hose is shut down, resulting in continued flow at the nozzle, which then may lead to significant operator injury.
What is needed is a simple and effective deadman system and method to insure that flow is redundantly terminated without undue delay under a variety of conditions so as to provide operator safety.
SUMMARY OF THE INVENTION
In accordance with the principles of the invention a system is provided to include a power supply, an actuatable valve, the actuatable valve connected via a line between the power supply and a storage vessel, an actuatable discharge/mixing valve attached to a portion of the storage vessel, the actuatable discharge/mixing valve connected via a line between the actuatable valve and a hose, a terminal end of the hose having a nozzle, a control input line connecting the power supply to a control valve positioned adjacent to the nozzle, and a control return line having a safety bleed positioned adjacent to the actuatable valve and connecting the control valve to the actuatable valve and the actuatable discharge/mixing valve such that any loss of pressure in the control return line results in closing the actuatable valve and the actuatable discharge/mixing valve as pressure is released through the safety bleed. With such an arrangement various configurations are possible which provide various redundancies in operator safety. These configurations may include, in one or more arrangements, an actuatable valve, an actuate able discharge/mixing valve, a safety bleed, and/or nozzle safety shutoff device.
REFERENCES:
patent: 5069391 (1991-12-01), Seaholtz
patent: 5216848 (1993-06-01), Abbott et al.
patent: 5239787 (1993-08-01), Abbott et al.
Davis and Bujold
Douglas Lisa Ann
Kashnikow Andres
P. K. Lindsay Co., Inc.
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