Fluid handling – With leakage or drip collecting
Reexamination Certificate
2000-03-06
2001-06-12
Hepperle, Stephen M. (Department: 3753)
Fluid handling
With leakage or drip collecting
C137S597000, C137S614190, C137S614210, C137S637200
Reexamination Certificate
active
06244291
ABSTRACT:
BACKGROUND OF THE INVENTION
In the field of chemical process sampling, there has been a divisional application based upon a long felt need for improved sampling valves. Either single or multiplex valves are needed to sample an ongoing chemical process by receiving gas or liquid and upon control actuation, extract a sample of a process stream to be introduced into a chemical process analyzer such as a gas or liquid chromatograph and after the sample is taken, the valve is closed to the process stream.
In multiplex applications a number of valves are each coupled to a different stream at their input and to a single process analyzer at their output. The valves are actuated at different times to provide sampling of each of the streams without intermixing or cross contamination of samples. At the close of the sampling cycle, any residual of the sample stream is discharged from the actuated valve via a common vent output.
Since the valves must be usable in a variety of industries, sampling of a variety of process streams is expected. It is therefore essential that the valves be chemically resistant and diffusion resistant to the sample streams, which they might encounter. More specifically, they must be chemically resistant to material such as strong oxidizers, reducing agents, petrochemicals, especially aromatics and any combinations of such compounds.
Since the valves may be sampling streams from a process which is conducted at elevated or refrigerated temperatures, the valves must operate reliably in a range of the least 0 degrees F. to 300 degrees F.
The valves need to have a high degree of external leak integrity to prevent fire or toxic hazard as well as to minimize what is termed, fugitive emissions.
From the structural standpoint, the valves need to be small in size, simple in design and preferably available for assembly into a variety of modular forms for multiplexing a number of valves together at the input of the single process monitor.
The selection of materials for the valve's structure, as well as its essential seals, must all meet the standard of chemical and diffusion resistance as well as freedom from abrasion or wear which could cause contamination of samples, wear, leaks and shortened operational life. For a truly acceptable valve, some minimum one million cycles of trouble-free operation is needed.
Internally, it is desired that the flow path from the input stream through the valve be as straight or clear is possible, of minimum volume, and without dead end passages which can retain sampled fluid after the sample procedure is completed.
Heretofore, single valves and multiplex valves have been developed but they have failed to meet all of the standards set forth above. Complexity of design, the requirement of numerous seals and presence of confined passage ways have been common. The need for many seals, the failure or abrasion of any one of which may cause leak or contamination of the sample has definitely been the major cause of shortened life of the valves.
BRIEF DESCRIPTION OF THE INVENTION
Faced with the foregoing state-of-the-art, I have determined that it is possible to develop such compact reliable process stream sampling valves which may be using alone or in multiple valve assemblies and achieve an operational life of at least one million cycles of trouble-free operation and without cross contamination or unwanted discharge of the sample stream.
I have accomplished all the foregoing objectives in a valve which is basically a rectangular valve body which defines a two-part cylinder with two independent operating pistons, each with a piston rod carrying a valve seal. The two pistons are biased away from each other to provide the closure of the two valves or ports namely the input valve or port and the output valve or port. The pistons are biased away from each other by single spring to normally maintain both of the input and output ports closed. When actuated at an actuation port, the actuation pressure is in communication with the opposite sides of both pistons from the common bias force, namely the spring, whereby the actuation pressure simultaneously opens both valves or ports by moving the pistons toward each other and closes the vent port.
The pistons on their adjacent faces include a valve seat and a valve poppet aligned and positioned so that upon actuation of the sampling valve, actuation pressure opens the input and output valves or ports, a vent valve or port which is normally in communication with the vent port is closed and the passages within the two pistons define a process gas flow route through the valve body and their piston rods between the inlet port and the output port. The outlet port is normally coupled to suitable analytic apparatus such as a gas chromatograph.
Only two sliding seals on the piston rods, two poppet seat seals and one poppet of the inlet and outlet valve, and the seal of the vent valve are exposed to process gas or liquids. Any remaining seals are either static or travel in the valve in areas which are not normally exposed to the primary process gases or liquid.
The valves are exceedingly simple in design, few parts are required and unessential parts such as end plates and mounting brackets are eliminated while improving the performance and versatility and ease of selection and installation. The interior volume of the process sampling valve of this invention, exposed to the process fluids sampled, is held to a minimum. The valves may be tailored to different and extreme process environments merely by change of relatively few seals to match the requirements of the process stream to be monitored.
This invention may be characterized as a normally closed, pneumatically operated, double block and bleed valve, designed for stream selection in liquid or gas analytical systems. The double block and bleed type valve provides leak integrity to assure against cross contamination of sample streams in multiple stream configurations. The bleed feature minimizes the chance of the previous sample stream being trapped inside the valve during analytical cycles.
Each compact module is designed to handle one stream. Multiple module configurations are available to handle multiple streams. In a multiple module configuration, the outlet ports are common to eliminate dead volume. Each module(s) is mounted on a base that contains a common outlet and vent port. The inlet and air actuator ports are located on each individual valve module. An individual valve module may be removed without disturbing the sealing integrity of other modules. Modules are simple to disassemble for easy maintenance.
Tapered Kel-F seats are used to seal the inlet, outlet and vent valve ports to eliminate leakage and chemical attack in liquid and gas systems. The flow path through each valve is unrestricted to minimize pressure drops. Internal volume is also minimized to 0.48 cc.
Operating pressure ranges of 300 PSIG (21 bar) and 500 PSIG (35 bar) and operating temperatures up to 300° F. (150° C.) allows for a variety of system designs. The minimum 40 PSIG actuating pressure is ideal for systems where there may be fluctuations in air pressure.
REFERENCES:
patent: 1332000 (1920-02-01), Pfau
patent: 3957079 (1976-05-01), Whiteman
patent: 4703913 (1987-11-01), Hunkapiller
patent: 4856551 (1989-08-01), Brakelmann
patent: 5305788 (1994-04-01), Mayeux
patent: 5361805 (1994-11-01), Mayeux
patent: 5558129 (1996-09-01), Mayeux
patent: 5645102 (1997-07-01), Brackelmann et al.
patent: 5765591 (1998-06-01), Wasson et al.
patent: 6014983 (2000-01-01), Sondergaard et al.
Bernardo Sam
Hepperle Stephen M.
Wagner John E.
LandOfFree
Process sampling selection valves does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process sampling selection valves, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process sampling selection valves will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2480964