Although Sapphire is located in the greater Houston area, its service area extends far beyond those boundaries, and a great many industries throughout the state of Texas have benefited from the products and services offered by Sapphire Hydraulics. Hydraulic flow-control valves are essential components of most hydraulic systems, and they act as regulators and shut-offs for many systems that have fluid flowing through them. 227 US-90 ALT Figure 3. By-Pass Meter-Out Speed Control.This type of action can only be achieved by assembling individual components into a speed control system. Flow regulator adjusts to variations in inlet and output pressures. Hydraulic check valve for flow control open and close at controlled, adjustable speeds to provide for smooth operation and reduce pressure surges associated with conventional check valves. 6. Diaphragm valves are used for throttling functions, and theyre suitable for applications that involve the usage of corrosive liquids at low pressure and low temperature. Hydraulic Motor Speed Control.Although hydraulic motors can be controlled with the same speed control circuits used for cylinders, this circuit gives the best speed regulation, and therefore the widest range of adjustable speed with acceptable performance. No comments have been added yet. Flomatic is a Valve Manufacturer Certified under ISO 9001 and ISO 14001 Quality and Environmental Management Systems. This approach may be used to advantage when working with a special kind of adjustable orifice which for one reason or another is not available with built-in pressure compensation as a completely self-contained flow control valve. An orifice can be a drilled hole in a fitting, in which case it is fixed; or it may be a calibrated needle valve, in which case it functions as a variable orifice, Fig. Gate valves are suitable for high-pressure and high-temperature applications and are generally used for on/off non-throttling functions which require a straight-line stream of fluid and minimal restriction. (713) 331-1131. Rosenberg, TX 77471 Because theyre able to prevent the backflow of fluids, these types protect compressors and pumps within the system. Control accuracy may be 5%, possibly less with specially calibrated valves that operate around a given flow-rate point. 7. 2007 2022 All Rights Reserved Flomatic Corporation, C900 - Flow Control Valve, Maximum Rate Control. 2022 Womack Machine Supply Co. All rights reserved, Pressure Compensated Hydraulic Speed Control - Part 1. How Does a Hydraulic Flow-Control Valve Work? 6. Modification of a pressure reducing valve to make a normally open 2-way valve for use in Figures 2 and 4. A globe valve is a general-purpose flow control valve that is very popular in applications involving high temperatures. Ball valves are some of the simplest types of flow-control options, and these consist of a ball that is attached to a simple handle. 4. INTERNATIONAL CALLERS: 518-761-9797 Flow-control valves include simple orifices and sophisticated closed-loop electrohydraulic valves that automatically adjust to variations in pressure and temperature. If a suitable 2-way, normally open spool valve is not available for the circuits of Figures 2 and 4, a pilot-operated pressure reducing valve may be modified for this service as shown in the notes on the drawing. Hydraulic Hose Fittings & Connector Sizes Charts. Pressure-compensated, variable flow-control valves are available with integral reverse-flow check valves (which give fluid unrestricted flow in the opposite direction) and integral overload relief valves (which route fluid to tank when a maximum pressure is exceeded). The purpose of flow control in a hydraulic system is to regulate speed. Should inlet or load pressure (or both) vary, the primary circuit has priority over the secondary as far as supplying the design flow rate is concerned. https://www.linkedin.com/company/11091630, New Walvoil Technology Improves Hydraulics Efficiency in Mobile Machinery, Medium-Pressure Ball Valves Provide a Rugged Solution, Caterpillar Overhauls Hydraulics for New Next Gen Compact Wheel Loaders, Electric Valve Actuator Replaces Undersea Hydraulic Actuators, Modeling Pressure Changes in Hydraulic Systems, Troubleshooting Challenge: Pressure Poses Problem, The Functional Safety Revolution in Electrohydraulics, Vehicle Maintenance Gets a Lift From Hydraulics. When the upstream pressure becomes less than the downstream pressure, the hydraulic control valve closes to prevent reverse flow at a controlled speed by introducing control water above the diaphragm from the downstream side through a second needle valve. The flow rate is also responsible for determining the rate of energy transfer at any specific level of pressure. If this valve is used in the motor inlet as in Figure 4, an external pilot connection must be brought out and the internal passage plugged. Pressure-compensated, variable flow valvesThis flow control is equipped with an adjustable variable orifice placed in series with a compensator. To offset the effects of such temperature variations, temperature compensators adjust the control orifice openings to correct the effects of viscosity changes caused by temperature fluctuations of the fluid, Fig. Want to start the conversation? 4. document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); Hydraulic In-Line Adjustable Variable Flow Control Valve w/ Free Reverse Flow, 3/8 NPT, Hydraulic Adjustable Variable Flow Control Valve w/ Relief, 0-30 GPM, #12 SAE, Hydraulic Adjustable Variable Flow Control Valve, 0-16 GPM, #8 SAE, Hydraulic Adjustable Variable Flow Control Valve w/ Relief, 0-16 GPM, #8 SAE, Hydraulic Adjustable Variable Flow Control Valve, 0-30 GPM, #12 SAE, Used to stop or start a hydraulic motor or cylinder, Once set, will maintain constant speed even with variation of loads, Excess flow is returned to tank or can be used to power another function. Most other flow-control valves operate in a similar way, i.e. In either case, however, the pilot poppet and spring must be removed and the drain connection must be run directly to tank. Figure 5. Figure 2. Using individual adjustable orifice and 2-way, normally closed by-pass valve, a bleed-off meter-out speed control system may be designed. Figure 3 has the advantage of meter-out control for maximum cylinder stability, plus the advantage of bleed-off action in the oil supply to the blind end of the cylinder. Check valves are unidirectional and are frequently used in hydraulic systems, pumps, and irrigation sprinklers. We will show there are other advantages to using individual components in place of a self-contained pressure compensated flow control valve. 1. You can think of directional control valves as something like fluid switches that enable the appropriate contacts, in that they direct a kind of high-energy input stream to an actuator inlet, thereby providing a necessary return path for oil, which is low-energy in nature. Flow-control valves in hydraulic systems are generally used to regulate the pressure in the flow rate of either gases or liquids as they travel through a pipeline. All the devices discussed here control the speed of an actuator by regulating the flow rate. Pressure- and temperature-compensated, variable flow valvesBecause the viscosity of hydraulic oil varies with temperature (as do the clearances between a valves moving parts), output of a flow-control valve may tend to drift with temperature changes. Hydraulic flow-control valves also have a secondary function of managing the energy transfer rate at a specified pressure. 7, is essentially a flow-control valve that supplies fluid at a set flow rate to the primary circuit, thus functioning as a pressure-compensated flow-control valve. There is no self-contained pressure compensated flow control on the market which will give this action. These are adjustable speed control valves for hydraulic cylinders and motors. 2022 Sapphire Hydraulics. They provide 100% tight fluid shut-offs and are commonly used in industries related to food and beverage, wastewater, and chemical application. When used to control flow, the orifice is placed in series with the pump. Since the ball has a hole through its center, when the handle is turned, the balls hole is aligned with valve openings so that fluid-stream becomes possible. When the upstream (inlet) pressure is greater than the downstream (outlet) pressure, the hydraulic control valve moves to the open position at a controlled speed by exhausting control water from above the diaphragm to the downstream side through an adjustable needle valve. Obviously these valves are not suitable for compressed air, and work most efficiently on hydraulics at the higher pressures. The three components shown - orifice, check, and 2-way spool valve are all contained within the housing of the flow control valve shown in Figure 1. The best type of flow-control valve to use depends on the design parameters of the application. Figure 4. In addition to offering the finest line of products in the industry, Sapphire Hydraulics also specializes in the hydraulic hose repair, maintenance, and service of all custom hydraulic equipment. The most complex of these options are able to detect pressure changes and make appropriate responses, or they are capable of monitoring flow rate and making the correct response when that rate goes beyond a predefined threshold. It would give the same excellent performance and would minimize heating of the oil. 2022 Endeavor Business Media, LLC. Priority valve supplies a set flow rate to a primary circuit. 3. 1(b). The compensator is a standard 2-way, pilot-operated spring returned, spool-type valve, normally open, or, a pilot-operated pressure reducing valve can be modified for this service as shown below. This post will focus on the functionality of hydraulic flow-control valves, the types that are available today, and what applications they are most frequently used in. Pressure-compensated, variable flow-control valve adjusts to varying inlet and load pressures. Troubleshooting Challenge: O-rings Missing from Valve Stack, Compact Design Solves Check-Valve Challenges. 1990 by Womack Machine Supply Co. Figure 4 is series metering in the motor inlet. The bypass flow regulator is more efficient than a standard flow regulator. Figure 2. Bypass flow regulatorsIn this flow regulator, flow in excess of set flow rate returns to reservoir through a bypass port, Fig. Figure 5. It is also necessary to use a piston-type motor because this type has a case drain which will carry out the internal slippage without letting it pass through the adjustable orifice to worsen the speed regulation. By contrast, directional control doesnt really deal with energy management but instead directs the energy transfer system to the appropriate location in the system at just the right moment. In addition to the adjustable metering orifice, there is a "compensating" spool which can modulate the flow during operation to keep it constant at the value set on the metering orifice by an operator. Sponsors of Friendship Circle of Houston, Texas. Alternatively, a 2-way normally closed valve could be used to bypass excessive oil at the motor inlet. The adjustable orifice and the compensating spool work together, and are built into a common body. In this issue we intend to show how a speed control system can be designed by using any kind of adjustable metering orifice, and adding a separate compensating spool valve to work with it for unusual effects. 2. Thus it can be said that a secondary function of directional control devices would be to time the cycle of events. However, individual components may be selected and plumbed separately to achieve the same results. 5. Figure 4. The reason for this is the internal slippage which causes the speed regulation to become progressively worse at lower speeds. Simple fixed orifice (a) and variable orifice (b) flow controls. In Figure 3, assuming the spring in the compensator spool has a cracking pressure of 75 PSI, when flow through the adjustable orifice increases to produce a pressure drop across the orifice of greater than 75 PSI, pressure on the upstream side of the orifice serves as pilot pressure to cause the compensator spool to open just enough to by-pass all oil in excess of that amount which produces 75 PSI drop across the orifice, thus keeping a constant flow through the orifice. The excess oil which is forced to by-pass to tank can by-pass at load pressure instead of relief valve pressure, thus saving power and reducing heat generation during periods when the cylinder is idling or working lightly loaded. Both types are non-compensated flow-control devices. The most common kinds of hydraulic flow-control valves include the following designs: needle, diaphragm, butterfly, plug, and ball. Contact us today with any questions you have about our products or services or to receive a quote on any type of part or service you require. 3. This compensating ability provides closer control of flow rate under varying pressure conditions. Therefore, a pressure compensated flow control valve is called for on applications where constant speed must be maintained even when the load changes. The by-pass, meter-out circuit of Figure 3 is the best speed control for cylinder or motor, with best stability and minimum oil heating, but cannot be used in systems with more than one branch circuit operating from a pump. Bypass flow regulators return excess flow from pump. They have leak-proof seals that will guarantee a tight shutoff, and theyre very easy to maintain and clean. Pressure compensated flow control. Why Hiring an Experienced Hydraulics Tech Over an Apprentice Matters, How to Check Heavy Equipment Hydraulic Fluid Levels. The simplest design for any flow-control valve will be one that has an aperture that can be opened or closed for the purpose of managing the flow rate. 1(a), is the most elementary method for controlling flow and can also be used as a pressure-control device. Have a hydraulic issue thats slowing down progress at your business that you need rectified quickly? Glens Falls, NY 12801 USA, PHONE: 1-800-833-2040 If such a valve is hard to come by, one can be made by modifying a pilot-operated pressure reducing valve as shown on the backside of this sheet. Flow can vary from closed to fully open depending on the position of the lever. When assembling hydraulic circuitry, there are a number of options possible for controlling flow, and these can range from the very basic to ultra-sophisticated controls managed by electronics. In general, the categories which these flow control valves fall into are: gate, diaphragm, check, globe, and pinch valves. FAX: 1-800-314-3155. A flow-control valve in any hydraulic system is tasked with the regulation of fluid speed, and by regulating the rate, it can control the speed of an actuator in the system. An orifice, by itself, cannot hold the flow constant if the load on the cylinder or motor should change. Since fluid can be managed by a directional control valve, it is also possible to achieve flow rate measurement and pressure control through their usage. Below 2000 PSI, their efficiency becomes increasingly poor. To be able to operate a hydraulic motor over a wide speed range - 10 to 1 or more - it is necessary to place the adjustable orifice in the motor outlet. The two are related in that the actuator force multiplied by the distance through which it moves (stroke) equals the work done on the load. FLOMATIC CORPORATION When youre looking for the best option in a hydraulic flow-control valve, you should contact the leader in all hydraulic services: Sapphire Hydraulics. This company assumes no liability for errors in data nor in safe and/or satisfactory operation of equipment designed from this information. Also, a compensating piston adjusts to variations of inlet and outlet pressures. CF (Controlled Flow): flow coming from this port is pressure compensated and proportional. Globe valves are used to start, stop, and regulate fluid, and theyre good for on/off applications as well as throttling applications. Pinch valves are an inexpensive category of flow-control valves and use a pinching effect to manage the flow of fluids. Widest Range of Variable Speed. OrificesA simple orifice in a hydraulic line, Fig. Because hydraulic flow-control valves have a number of different functions within hydraulic systems, there are several different types of flow-control valves to accommodate each of those functions. A standard by-pass valve will serve the purpose if it is a direct-acting rather than a pilot-operated type. Meter-Out Speed Control. The energy transferred must also equal the work done. Flow rate is controlled by throttling fluid across a variable orifice regulated by the compensator piston. They have two ports, one for fluids to enter through and one for fluid discharge. All Rights Reserved. Flow rate also determines rate of energy transfer at any given pressure. Fluid is routed at a controlled flow rate to the primary circuit, and bypass fluid can be used for work functions in secondary circuits without affecting the primary one. Adjustable orifice, compensating 2-way valve, and check valve connected to provide pressure compensated meter-out speed control. Best speed control for a hydraulic motor. Pressure- and temperature-compensated, variable flow-control valve adjusts the orifice size to offset changes in fluid viscosity. Priority valvesA priority valve, Fig. Above are general guidelines based on common application characteristics. Hydraulic Adjustable Variable Flow Control Valve, 0-30 GPM, 3/4 NPT, Pressure Compensating Variable Flow Control Valve. Flow regulatorsThese devices, Fig. This site requires you to register or login to post a comment. Within a hydraulic system, a flow-control valve will be used to control the rate of flow to hydraulic cylinders and motors, which in turn will impact the speed of both of those devices. This is done in combination with adjustments to the control orifice for pressure changes as well. Eight different types of flow-control valves are commonly used in hydraulic systems. Demand-compensated flow control bypasses full pump output to tank during idle portion of work cycle. This would be a circuit comparable to Figure 3. 2, are slightly more sophisticated than a fixed orifice and consist of an orifice that senses flow rate as a pressure drop (P) across the orifice. Flow-control valves are extremely important for optimizing the performance of the system, so choosing the right valve for the job is likewise crucial: a flow-control valve manages the flow rate in any given portion of a system of hydraulic circuitry. There must be flow to the primary circuit for this type of valve to functionif the primary circuit is blocked, the valve will cut off flow to the secondary circuit. Pressure Compensated Flow Control Valves. The compensator spool is a 2-way, pilot-operated, normally open spool valve with spring return. All rights reserved. When its desired to reduce or shut off the flow, this handle can be used to position the ball perpendicular to all of the valve openings, which effectively blocks the fluid. 15 Pruyn's Island Drive EX (Excess Flow): Flow coming from this port is pressure compensated. If lever is set to 0 all flow will exit the valve from this port. The compensator spool in this figure is a 2-way, pilot-operated, normally closed spool valve. Flow in excess of that required by the primary circuit bypasses to a secondary circuit at a pressure somewhat below that of the primary circuit. they provide some mechanism for either allowing flow to take place or blocking it. Figure 1. Compensation can be added to any kind of needle, gate, globe, ball, or diaphragm valve. The compensator automatically adjusts to varying inlet and load pressures, maintaining an essentially constant flow rate under these operating conditions to accuracies of 3% to 5%, Fig. Figure 3. Demand-compensated flow controlsFlow controls can also bypass excess system flow to a secondary circuit, Fig. But if the valve is used in the motor outlet as in Figure 2, the spool is piloted from its own outlet and the external pilot port is not needed. As background for this circuit, remember that hydraulic motor performance is best when operating at maximum speed, and becomes progressively poorer as speed is reduced. If so, click to download our brochure and discover why Sapphire Hydraulics is the right repair service company for you! If the stream doesnt arrive at the appropriate place at just the right time, it wont really matter if you are able to control the energy transfer by using flow controls. Gear and vane-type motors sometimes will not cover more than a 3 to 1 or 4 to 1 range with good performance. Actuator speed determines the rate of energy transfer (power), and speed is thus a function of flow rate. Since actuator speed determines the horsepower or energy rate transfer, the actuator speed is therefore considered to be an important function impacting the flow rate. 5.
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