Flow Control Valves
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Pressure compensated flow control valves are used to limit or regulate flow.

Three basic types of cartridges are available; restrictive-type, priority-type, and divider/combiner type.

Combination valves in manifolds for additional features such as fully adjustable flow or free reverse flow are also available.

 

Restrictive-type pressure compensated flow control valves are two-ported valves that maintain a constant flow rate from 1 to 2 regardless of load pressure changes in the circuit downstream of 2.  The control orifice in the spool is factory set to the flow specification. The valve begins to respond to load changes when flow through the valve creates a pressure differential across the control orifice of approximately 7 bar [100 psi], and accurately maintains flow within +/- 10% across the range of 35‑207 bar [500‑3000 psi]. Reverse flow from 2 to 1 returns through the control orifice and is non-compensated.

 

Restrictive-type flow control valves can be used in meter-in or meter-out applications to control actuator speeds.

 

flow-control-valves-circuits-1 flow-control-valves-circuits-2

Flow divider/combiners are pressure compensated valves. When the valve is functioning as a divider, it will divide input flow from 3 to the two outputs at 2 and 4 according to a preset ratio. This ratio is unaffected by pressure. When the valve is functioning as a  combiner, it will combine the flow from the two inputs from 2 and 4 into one output at 3. Note that a flow divider/combiner is specified with a nominal flow rate for each leg. When operating with flow rates higher than specified, the dividing and combining ratios will be maintained, but at a cost of higher pressure drop and associated heat generation. When operating with lower flow rates than specified, the dividing and combining ratios are also maintained, but at a cost Hydraulic wheel motor circuit of accuracy. For example, a 22 l/min [5.8 US gal/min] : 22 l/min [5.8 US gal/min] flow divider will divide flow in a 50:50 ratio with an accuracy of ±10% (±2.2 l/min [±0.58 US gal/min]) per leg. With an input flow of 8.0 l/min [2.1 US gal/min], the flow division will be 4.0±2.2 l/min [1.1±0.58 US gal/min] per leg.

 

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Common applications for flow divider/combiners include:

 

  • Combining flow (forward) or dividing flow (reverse) to hydraulic wheel motors for vehicle drive application. 

    Note that an external orifice is added to allow more flow to one motor than the other while turning a corner (not shown).
     
  • Synchronizing motion of hydraulic cylinders. Note that if circuit operation results in a blockage of one cylinder port, the other port will also close. Consult factory for details.

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