pressure compensated hydraulic pump in stock

Drop in equivalent to Vickers PVE19AL05AB10A2100000100100CD0A hydraulic pressure compensated piston pump 19.48 GPM @ 1800 RPM 3000 PSI.3000 PSI maximum operating pressure. 2400 RPM maximum RPM.

Drop in equivalent to Vickers PVE19AR08AA10B21110001AE100CD0A hydraulic pressure compensated piston pump 19.48 GPM @ 1800 RPM 3000 PSI.3000 PSI maximum operating pressure. 2400 RPM maximum RPM.

Enerpac"s ZE platform of 10,000 psi electric/hydraulic pumps is offered in .75, 1, 1.5, 3, and 7.5 Hp motor options.  From there, endless combinations of global operating voltages, reservoir sizes, and manual and solenoid valve options will most certainly deliver the reliable performance of your most unique and demanding high-pressure application. LCD electrical features, heat exchangers, oil level temperature switch, pressure transducer, roll cage, skid bar, and foot switch control are added through the feature-defining build matrix.

Hydraulic pumps are an incredibly important component within hydraulic systems. IFP Automation offers a variety of pump and hydraulic system products that deliver exceptional functionality and durability. Our partner Parker’s extensive line of hydraulic pumps deliver ideal performance in even the most demanding industrial and mobile applications. In this post, we are going to spend time discussing pressure compensated and load sensing hydraulic pumps.

Do to the surface area of the servo piston and the pressure exerted on that area, a force is generated that pushes the swash plate of the pump to a lower degree of stroke angle.

The pump tries to maintain compensator setting pressure, and will provide whatever flow (up to it’s maximum flow rate) that is necessary to reach that pressure setting.

For more information on how you can make use of hydraulic pump technology in your applications, please contact us here to receive a personalized contact by an IFP Application Engineer:

Flexible and high-performing, the PVP Series hydraulic piston pump increases uptime with fast and reliable variable volume pumps engineered for medium pressure applications. PVP pumps feature thru-shaft capability and high-strength construction for greater productivity, while improving the work environment with quiet pump technology for reduced noise levels and easy-to-service components.

These pumps are designed for applications where light weight design, lower displacements, and multiple configuration capabolities are design requirements.

This Pressure Compensated Piston Pump is one of many pumps that the Hydraulic Megastore has to offer and they are all available for next day delivery.

For high speed mobile applications, we stock A10V pressure compensated piston pumps with displacements from 2.75 cu.in/r. (45.0cc) to 8.54cu.in/r. (140cc) and continuous pressure to 4,000 PSI. The A10V pumps come standard with load sensing compensator that can be used as a standard compensator. Heavy duty piston and shoe construction make for a rugged and reliable pump at high speed, pressure, and flow. Through drives are available on all sizes in the A10V series.

The RV1P are variable displacement vane pumps, with pilot operated hydraulic pressure compensator, which instantly adjusts the flow rate according to the circuit requirements. Energy consumption is reduced and adequate at every moment of the cycle. Those vane pumps have internal supply and suction double ducts. The pumping unit is equipped with double hydrostatic axial compensation, which improves volumetric efficiency and reduces component wear. The pressure compensator keeps the stator ring of the pumping group in an eccentric position by means of a piston controlled hydraulically by a pressure pilot stage. When the delivery pressure equals the pressure set on the pilot stage, the stator ring moves towards the center, adjusting the flow rate delivered to the required values of the system. In condition of zero flow demand, the pump delivers oil only to compensate for any leaks and piloting, keeping the pressure constant in the circuit. The response times of the controller are very low and such as to allow the elimination of the pressure relief valve. The gamma is made of four-dimensional groups, with displacements from 16 to 120 cm3/rev with operating pressures up to 250 bar, with clockwise rotation, with rectangular flange and tapered keyed shaft or with ISO 3019/2 flange and cylindrical keyed shaft. This pump is available with control for one or two pressure stages.

Pressure compensated pumps, pressure compensated flow controls or even just straight-up pressure compensators – these terms are thrown around constantly. But unless you’re a hydraulic specialist, you may not know what these are, let alone what they do. Of course, you’ve probably heard of systems analysts and cartographers too, but even thoseguys don’t know what they do.

The word pressureis self-explanatory, but just considering the meaning of compensategoes far to explain its use here. The dictionary says: reduce or counteract (something unwelcome or unpleasant) by exerting an opposite force or effect. Take that pressure!Your shenanigans are not welcome here! Okay, so we do want pressure and lots of it. But sometimes we don’t, and that’s where a compensator comes in.

A pressure compensator works by comparing two pressure signals, one of which is a target and the other a pilot reading of downstream pressure. I’ve created a diagram showing a cutaway of a pressure compensated flow control and a symbol for the same (note, these valves are not identical). The primary difference between the two examples is the location of the compensator. The cutaway places the compensation before the variable orifice, while the symbol example places the compensator afterthe orifice. However, both will work so long as the compensator measures the pressure drop across the orifice.

Because flow rate is a function of pressure drop, and because pressure differential changes with flow rate, these understandings allow us to make sense of pressure compensator operation. Starting with the pressure compensated flow control symbol on the right, the flow path starts at port 1 and continues past port 3 out to the subcircuit being regulated.

The compensator has a spring value of 90 psi, and just like this example, most often, the spring value comes fixed. The compensator spool uses two pilot passages to measure pressure drop across the needle valve. In this case, port b measures pressure upstream of the needle valve at port 1, while port a measures downstream pressure at port 2.

The compensator spool will open or close itself to maintain 90 psi of differential pressure across the needle valve. Should load-induced pressure increase at port 2, the yellow pilot path to port a will push the spool backwards to open the combined flow path from port 1 to port 3. Should downstream pressure again decrease or supply pressure upstream of port 1 increase, any differential pressure than 90 psi will push the valve closed to restrict flow.

The cutaway example works much the same way. The red inlet flow must first pass a metering notch before entering the orange chamber, where the flow accesses its input. Next, metered flow crosses from orange to yellow before exiting the valve at the top. The yellowpassage comprises the differential pressure to the tune of the spring (assume 90 psi once again) trapped by the magenta spool. The difference in pressure between the orange and yellow defines the pressure drop through the needle valve.

Should downstream load-induced pressure at yellow start to decrease pressure drop from orange to yellow, the magenta spool moves backwards to open the flow path from red to orange, thereby increasing flow to sustain 90 psi pressure drop. Conversely, should pump-side pressure increase upstream of red, the increased pressure in the orange chamber will close the magenta spool against the spring. With less flow entering the orange chamber, pressure drop from orange to yellow remains stable at 90 psi.

In many ways, a pressure compensator is both a pressure and flow valve, but really quite simple in operation. For more information on pressure compensators, watch the Lunchbox Session videos on the subject. Expertly narrated by Carl Dyke, the first in the series can be found here.

On a recent project, there was a 25 horsepower motor running a torque limited piston pump. When we were doing performance testing, everything worked out fine. As soon as I left, the customer was complaining about excessive heat generation leading to downtime waiting for the oil to cool.

At first, I thought that a relief valve may be set below the compensator pressure, but a quick check showed they were operating correctly. So I did some research.

The problem wasn’t clear until I talked with the pump manufacturer. In order to keep a pressure compensated pump cool, the oil needs to be circulated internally. Depending on the manufacturer, 1/4 of the flow may be dumped back to tank to keep the pump cool.

Pressure compensated hydraulic systems tend to overheat because oil is continually circulated to keep the pump cool. The higher the standby pressure, the more heat created. Adding heat exchangers, shutting the pump down and lowering or having adjustable stand by pressure can reduce the heat generated.

So you have spent the extra money to get a piston pump, but do you know that there is a hidden danger in built in to these pumps? Let’s explore the danger

It turns out that pressure compensated systems are always moving oil, even when in standby. I found out that roughly 3 to 4 gpm were being dumped back to tank through the pump’s case drain at the compensator pressure. This was nearly 7 horsepower that was wasted.

This situation was not detected in testing, because we ran back to back tests with no idle time in between. Once the idle time was added in, we discovered that the oil temperature rose around 1-2 degrees per minute. An impressive feat on 100 gallons of hydraulic oil.

Adding a heat exchanger is a very obvious solution. These are usually forced air radiators made for hydraulics that are installed on the return line or the case drain line.

If we assume that we have 7 hp of wasted power from our pump during idle time, that is 5.2 kWh of energy. At 12 cents per kWh, that is $0.63 / hr of idle time.

Luckily, pressure compensated systems will start in a loaded condition. There should be no (or little) pressure on the outlet and compensator. This means that when starting the motor, it won’t be anywhere near fully loaded. Since there is no pressure, it will take 1-3 seconds for the pump to produce enough pressure to load up the compensator. This will usually be long enough to minimize startup loads on the motor.

In some hydraulic systems, you just don’t need the system pressure you designed for. As a good designer, you have calculated your pressures and flows for less than what is available. As a result, you can reduce the standby pressure, but only minimally.

This option is the most expensive and most efficient. By using an electro-proportional relief valve (DO3 P to T relief valve for industrial applications), you can set the compensator pressure for exactly what you need for the current function. As the functions change, the compensator pressure changes.

This is the most expensive option because your PLC system is going to have to output an analog signal (usually 0 – 10VDC) to control the electro-proportional relief valve (also expensive). As a good designer, you will also want a pressure sensor to provide feedback on the system.

However, this system is fully customizable and can act similiar to a load sensing mobile system. Through careful programming, you can tailor your pressure setting to what that function needs at any particular time.

In this system, there would be one relief valve (main relief below) tied directly to the compensator and other relief valves are separated from the pressure line by 2 position, 2 way, normally closed solenoid operated valve. The main valve must be set at the maximum desired pressure so that if all else fails, the system will have a direct path of pressure control. The other valves can be activated, one at a time, to control the pressure for certain pressures.

Additionally, the system can be made to look quite neat as well. Having a multisection DO3 manifold with the pressure port connected to the compensator will provide the foundation. Often, you can get the main relief valve already incorporated into the manifold which is a big bonus. You can then add solenoid valves on as the first row. On top of those valves you can add the individual relief valves.

If none of the sections are energized, the pump will create the maximum pressure which is set in the manifold relief valve. If one or more sections are activated, the pump will create pressure to the lowest set active pressure. In the schematic above, you can adjust the compensator pressure to 600 psi, 1200 psi, 2200 psi or 2750 psi depending on which sections are activated.

This can be a subset of several other options. If your system idles for long periods of time, you can just have a 2 position, 2 way, normally closed solenoid valve dump the pressure to tank. This will destroke the pump and not create any heat.

Another option on this is to couple it with a timer so that if there is no demand for the system hydraulics, the solenoid will activate and the pressure will be reduced. When demand for higher pressures is needed, the PLC will deactivate this solenoid.

I actually chose two of these solutions. First, I put a two minute timer on when the system is in normal standby. There is also a 25 minute timer when the system is in the cutting mode. At the 25 minute cycle, only 500 psi is needed to operate a hydraulic motor and control the travel of a saw.

In cutting mode, I also reduced the standby pressure from 2750 psi to 500 psi reducing the needed power by 82%. Sweet! I accomplished this by adding a second compensator relief valve that is activated by a 2 position 3 way valve.

Pressure compensated systems are generally more efficient and with a torque limiter they will give you the best performance of any other hydraulic system. Unfortunately, they do have the drawback of heat generation when in standby mode. If the solutions above are applied, you can often eliminate the need for a heat exchanger.

Pressure compensation is the control of flow by compensating for the changes in load pressure. Most hydraulic systems today use pre-compensation as a means of maintaining consistent flow from an orifice or spool. However, there are applications when post-compensation has advantages over pre-compensation.

The fundamental difference is that with pre-compensation, the pressure drop across the orifice or spools is determined by the compensator. With post-compensation, the pressure drop is determined by the load sense (LS) spring inside the pump.

In post-compensated systems with multiple functions, the pump flow is divided at a fixed ratio. If flow settings exceed the pump output capability, the flow is reduced to each function at a fixed ratio. This is why post-compensation is sometimes referred to as “flow sharing”.

In post-compensated circuits, the pressure drop across each valve is determined by the load sense spring in the pump and all valves or orifices will have the same pressure drop. The load sense differential, sometimes referred to as standby, decreases when the pump cannot satisfy the total demand. All pressure compensators reference the highest load of the various functions.

The benefits include high efficiency under partial load and/or partial speed conditions and all functions slow down together at a fixed ratio when the pump cannot fully satisfy demand.

In the example below, the pump differential, or standby, is 200 PSI. The load sense pump will develop enough pressure to overcome the load and maintain a 200 PSI differential. The pressure drop across the valve or orifice remains fixed and is calculated by: system pressure minus the highest load pressure minus the compensator spring value.

The circuit below is an example of the flow sharing aspect. When another function is operated and the pump cannot fully satisfy the flow demand, the differential decreases. The pressure drop across each valve or orifice is reduced at the same fixed ratio, so the flow is divided, or shared, equally. In this example, each valve is fully open so total pump flow is shared equally between the functions.

So what happens when the functions require different flows and the pump cannot fully satisfy the total flow demand? The pump flow will be divided into the ratio of each function to total flow available. In the example below, the theoretical total flow demand is 42 GPM. The ratio of the function flow demand to total theoretical flow demand multiplied by the maximum pump flow is the resulting actual flow from each valve.

Post-compensation will increase stability and control in systems where demand can exceed the pump’s flow output. Because of its increased efficiency under partial load conditions, the compensator saves horsepower and reduces heat. It will also make the initial movement of actuators more predictable and provide better operator control.