Patent Application
20090071550
The present disclosure relates generally to fluid regulators and, more particularly, to in-line adjustable regulators.
Process control systems utilize a variety of field devices to control process parameters. Fluid regulators are commonly distributed throughout process control systems to control the pressures of various fluids (e.g., liquids, gasses, etc.). Fluid regulators are typically used to regulate the pressure of a fluid to a substantially constant value. Specifically, a fluid regulator has an inlet that typically receives a supply fluid at a relatively high pressure, which may vary or fluctuate, and provides a relatively lower and substantially constant pressure at an outlet. For example, a gas regulator associated with a piece of equipment may receive a gas having a relatively high pressure from a gas distribution source and may regulate the gas to have a lower, substantially constant pressure suitable for safe, efficient use by the equipment.
Fluid regulators typically control the flow and pressure of fluid using a diaphragm or piston having a set or control pressure force applied to one of its sides via a bias spring. The diaphragm is also operatively coupled directly or via a linkage to a valve component that is moved relative to an orifice of a seat that fluidly couples the inlet of the regulator to its outlet. The diaphragm or piston moves the valve component in response to a difference between the outlet pressure and the set or control pressure to vary the flow restriction through the regulator to achieve a substantially constant outlet pressure, which provides a balancing force to the other side of the diaphragm or piston that is equal or proportional to the set or control pressure.
Fluid regulators may provide a fixed (e.g., non-field adjustable) regulated output pressure, while other types of fluid regulators may provide one or more adjustments to adjustably set or vary the output pressure. Typically, an adjustable fluid regulator includes a spring that is compressed a predetermined amount to set its regulated output pressure. In some regulators, the amount of compression applied to the spring may be varied or adjusted to enable field adjustment of the regulated output pressure of the regulator. Typically, such field adjustable fluid regulators provide a knob or the like that can be grasped and turned to rotate a threaded rod that, possibly through one or more intervening components, changes a compression of the spring, thereby changing the regulated output pressure of the regulator. However, many of these adjustable regulators require a mounting surface and/or consume a relatively large amount of space, which may be scarce or lacking within control cabinets as well as other spaces in which the regulators are typically located throughout a process control system.
In accordance with one described example, an adjustable fluid regulator includes a body having a fluid inlet and a fluid outlet, and a first fluid regulator. The first fluid regulator includes a valve to control the flow of fluid from the inlet to the outlet, and a piston coupled to the valve via a stem, wherein the piston is to receive a pressure associated with the outlet. Additionally, the first fluid regulator includes a spring plate movable along a longitudinal axis of the stem, a spring disposed between the piston and the spring plate, and an adjuster engaged with the body to move the spring plate to change a compression of the spring and a regulated outlet pressure of the fluid regulator.
In accordance with another described example, an adjustable fluid regulator assembly includes a first fluid regulator and a second fluid regulator fluidly coupled to the first fluid regulator. The first and second fluid regulators form an in-line, two-stage fluid regulator. The first fluid regulator comprises an adjuster to change a fluid regulation pressure of the first fluid regulator, and the adjuster is configured to be field adjustable to change a compression of a spring of the first fluid regulator.
The example fluid regulators described herein provide one-stage or two-stage configurations having excellent regulation characteristics, which minimize the effect of inlet pressure changes on output or outlet pressure. Additionally, the example fluid regulators described herein provide compact configurations having adjustable (e.g., field adjustable) output pressure. The relatively compact configurations in comparison to known fluid regulators facilitates the use of the example fluid regulators described herein within control cabinets as well as other space-constrained process control environments. Also, the example fluid regulators described herein may be used as a compression tie between a piston and a valve, where the tie may be used to apply continuous additional force to produce an airtight seal if the valve should leak. Further, the example fluid regulators described herein may be used in relatively harsh service environments such as, for example, in connection with contaminated fluids, large temperature variations, high inlet pressures (e.g., 10,000 psig), etc.
As can been seen clearly in
In operation, the spring 148 biases or urges the piston 132 and, thus, the plug 120 away from the orifice 122 so that the valve 118 provides a normally-open configuration. Thus, in the absence of a pressure greater than atmospheric pressure at the outlet 140, the valve 118 is in a fully open condition. Further, as the inlet 112 passes pressurized fluid to the outlet 140, the pressure at the outlet 140 increases and the pressure on the surface 138 of the piston 132 increases and urges the plug 120 toward the orifice 122, thereby restricting the flow of fluid from the inlet 112 to the outlet 140. When the pressure at the outlet 140 is sufficiently high, a force balance condition (i.e., the pressure exerted by the spring will balance against the pressure at the outlet 140) will be achieved so that the pressure at the outlet 140 is at a substantially constant pressure lower than the pressure at the inlet 112. The force balance-based operation of such fluid regulators is well known and, thus, is not described in greater detail herein.
In contrast to known fluid regulators, in the example fluid regulator 200, includes a compression spring 248 is disposed between a spring plate 250 and the piston 232. The spring plate 250 is slidably movable along the longitudinal axis of the stem 226. To guide and facilitate the sliding of the spring plate 250, the spring plate 250 may include tabs or projections 252 and 254 that slide within an opening or channel 256 of the body or housing 202. To enable adjustment of the control pressure of the example fluid regulator 200, an adjusting ring 258 is provided. The adjusting ring 258 may be threadably engaged via threads 260 and 262 to the lower or first portion 204 of the body or housing 202 so that rotation of the adjusting ring 258 moves the spring plate 250 toward the piston 232 to increase the compression of the spring 248, which increases the regulated output pressure of the fluid regulator 200, or away from the piston 232 to decrease the compression (i.e., enable expansion) of the spring 248, which decreases the regulated output pressure of the fluid regulator 200. Thus, as can be clearly seen in
While the example adjustable in-line fluid regulators 200 and 300 described herein are depicted as being generally cylindrically-shaped, any other shape(s) could be used instead. For example, the casings or bodies used may have a polygonal (e.g., rectangular) cross-section. Additionally, while the adjusting ring mechanisms described herein are depicted as being directly, manually adjustable, any variety of gearing and/or electromechanical adjustment mechanism(s) may alternatively or additionally be employed to facilitate movement of the spring plates 250 and 316. For example, a small electric motor may be coupled (e.g., via gears or the like) to the adjusting ring to rotate the ring and adjust the position of the spring plates 250 and 316 by activating the motor. Still further, one or more locking rings may be used in addition to the adjusting rings 250 and 316 to enable the position(s) of the adjusting rings 250 and 316 to be mechanically fixed or locked in place (e.g., by counter-tightening the locking ring(s) against the adjusting ring). Additionally, the adjusting and/or locking rings may include multiple flats or other features to facilitate the use of tools (e.g., wrenches, pliers, etc.) to turn or rotate the adjusting rings.
Although certain apparatus have been described herein, the scope of coverage of this patent is not limited thereto. To the contrary, this patent covers all methods, apparatus, and articles of manufacture fairly falling within the scope of the appended claims either literally or under the doctrine of equivalents.
