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Product/Company Introduction SeminarProduct/Company Introduction SeminarPressure Control Cartridge ValvesPressure Control Cartridge Valves


© 2008 Sun Hydraulics Corporation

Product Overview

PRESSURE CONTROLPRESSURE CONTROLCARTRIDGE VALVESCARTRIDGE VALVES

PRESSURE CONTROLPRESSURE CONTROLCARTRIDGE VALVESCARTRIDGE VALVES

© 2008 Sun Hydraulics Corporation2



Pressure ControlsPressure ControlsPressure ControlsPressure Controls

• Relief• Sequence• Reducing• Reducing/Relieving




• Normally closed devices used to limit or regulate pressure

• Many variations to meet application requirements• Available in 2, 3, and 4 port configurations• Used to protect pumps or actuators, or maintain

constant system pressure• All hydraulic systems feature at least one relief valve

Pressure Controls - ReliefPressure Controls - ReliefPressure Controls - ReliefPressure Controls - Relief




Relief Valve – Technical OverviewRelief Valve – Technical OverviewRelief Valve – Technical OverviewRelief Valve – Technical OverviewRP*C, Pilot Operated, Balanced Piston Relief

• Accurate pressure control• Low pressure rise with flow• Smooth and quiet• Moderately fast response time• Viscosity sensitive• Susceptible to silting




Relief Valve – Technical OverviewRelief Valve – Technical OverviewRelief Valve – Technical OverviewRelief Valve – Technical OverviewRD*A, Direct Acting Relief

• Differential area design• Typically smooth and quiet performance• Essentially zero leak (suitable for load holding)• Dirt tolerant• Very fast response• Difficult to adjust under pressure• Higher pressure rise with flow




Relief Valve – Technical OverviewRelief Valve – Technical OverviewRelief Valve – Technical OverviewRelief Valve – Technical OverviewAdvantages

Relief Valve Comparison

• Fast response• Low leakage• Dirt tolerant• Capable of operating over a wide

temperature range• Low over/undershoot• Common flow path with P/O design

• Wide pressure range• Low hysteresis• Easier to adjust when operating at

high pressures• Low override curve• Screened orifice• Common flow path with direct acting

2

1

Port 1 - InletPort 2 - Outlet 2

1

Port 1 - InletPort 2 - Outlet

Direct ActingRelief Valves

Pilot OperatedRelief Valves

(Sliding Spool)




Relief Valve – Technical OverviewRelief Valve – Technical OverviewRelief Valve – Technical OverviewRelief Valve – Technical OverviewDisadvantagesRelief Valve Comparison

• Moderate hysteresis levels (not equivalent to P/O versions)

• Moderate pressure override• Multiple spring ranges required to

optimize performance• Difficult to adjust when operating at high

pressures

• Higher overshoot/undershoot potential• Internal leakage when closed• Temperature limitation• Contaminant sensitive in dirty

systems

2

1

Port 1 - InletPort 2 - Outlet 2

1

Port 1 - InletPort 2 - Outlet

Direct ActingRelief Valves

Pilot OperatedRelief Valves

(Sliding Spool)




Relief Valve – Technical OverviewRelief Valve – Technical OverviewRelief Valve – Technical OverviewRelief Valve – Technical OverviewRP*S, Pilot Operated, Balanced Poppet Relief

• Combines features of pilot operated and direct acting relief valves• Smooth and quiet pressure regulation• Very low leakage• Dirt tolerant• Adjustable under pressure• Very fast response• Eliminates erosion cavity damage




Relief Valve – Technical OverviewRelief Valve – Technical OverviewRelief Valve – Technical OverviewRelief Valve – Technical OverviewRBA*, Direct Acting, Pilot Stage Relief

• Remotely controls pressure setting of other pilot operated valves

• Capacity limited to pilot flow—should only be used with valves with comparable pilot flows

• Fast response

To SecondarySystem To System

RemoteControl or 2nd

SystemPressure




Relief Valve – Technical OverviewRelief Valve – Technical OverviewRelief Valve – Technical OverviewRelief Valve – Technical OverviewRPGT, Pilot Operated, Balanced Poppet, Soft Relief

• Pilot-operated relief that limits maximum system pressure and also the rate of pressure rise

• Adjust screw determines the maximum setting and an initial (threshold) setting

• Valve opens at threshold and ramps closed (or to maximum setting) at a constant rate in about 250 ms

• Controlled rate of rise results in less dynamic stress in a system and no pressure spikes




Relief Valve – Technical OverviewRelief Valve – Technical OverviewRelief Valve – Technical OverviewRelief Valve – Technical OverviewSoft Relief Function




Relief Valve Response Comparison

Relief Valve – Technical OverviewRelief Valve – Technical OverviewRelief Valve – Technical OverviewRelief Valve – Technical Overview

Ultimate Pressure

System Designed

Maximum Pressure

System Designed

Maximum Pressure and

Ultimate Pressure

Threshold

Pressure




Relief Valve – Technical OverviewRelief Valve – Technical OverviewRelief Valve – Technical OverviewRelief Valve – Technical OverviewRV*A, Ventable, Pilot Operated, Balanced Piston Relief

• Essentially a pilot-operated relief valve with a vent port that connects between the main piston and pilot stage

• Vent provides for remote control with other pilot or two-way valves by short circuiting the pilot stage

• If port 3 is blocked – valve operates as a standard relief If port 3 is open to tank – main section is wide open

• Same general characteristics as a pilot-operated relief valve




Relief Valve – Technical OverviewRelief Valve – Technical OverviewRelief Valve – Technical OverviewRelief Valve – Technical OverviewRV*D, Ventable, Pilot Operated, Balanced Piston Relief

with External Drain

• Same as the RV*A valve except with a separate drain for the pilot stage• Valve is insensitive to back pressure at port 2• Can be thought of as a ventable sequence valve• Same general characteristics as a pilot-operated relief valve




Relief Valve – Technical OverviewRelief Valve – Technical OverviewRelief Valve – Technical OverviewRelief Valve – Technical OverviewRQ*B, Pilot Operated, Kick-down Relief

• Act similar to a circuit breaker in an electrical system• When pressure at the inlet reaches the valve setting, valve

kicks completely open• Valve remains open as long as pressure at port 1 exceeds

pressure at port 2• To reset valve flow must cease• Same general characteristics as a pilot operated relief valve




Pressure Controls - SequencePressure Controls - SequencePressure Controls - SequencePressure Controls - Sequence• Normally closed devices used to control a sequence of actions (similar

to a relief valve with separate drain line)• Supplies flow to a secondary circuit once the pressure at port 1 exceeds

the setting of the valve• Can be used as a relief if back pressure is present in system• Assures that a priority function is completed before a secondary function

begins– Insures a part is clamped before machining can begin– Insures a clam shell bucket is closed before it can be lifted




Sequence Valve – Technical Sequence Valve – Technical OverviewOverview


SX*A, Direct Acting Sequence

• Similar construction to the RD relief valve• Setting of valve controls the pressure at port 1

relative to drain pressure at port 3• Extremely low leakage – suitable for load holding






SC*A, Direct Acting with Reverse Flow Check Sequence

• Similar construction to the RD relief valve• Setting of valve controls the pressure at port 1

relative to drain pressure at port 3• Extremely low leakage – suitable for load holding• Incorporates an integral check valve to provide

reverse flow from port 2 (sequence) to port 1 (inlet).






RS*C, Pilot Operated, Balanced Piston Sequence

• Similar construction to the RP relief valve• Setting of valve controls the pressure at port 1

relative to drain pressure at port 3• Insensitive to back pressure at port 2 – can be

used to regulate pressure in place of a two port relief valve if there is pressure in the return line






RS*E, Air Controlled, Pilot Operated, Balanced Piston Sequence

• Similar to the RS*C expect this version uses compressed air over a diaphragm instead of an adjustable spring to control the pressure setting

• Air supplied in hex end of cartridge• Hydraulic setting is directly proportional to air pressure at

ratio of 20:1 (hydraulic:air)• Maximum air pilot pressure should not exceed 150 psi






SQ*B, Kick-down Sequence

• Similar to the RQ*B in construction and function• When pressure at the inlet reaches the valve setting,

valve kicks completely open• Valve remains open as long as pressure at port 1

exceeds pressure at port 2• To reset valve flow must cease• Valve setting is insensitive to back pressure at port 2

One

Note:Pressure to cylinder 1 dropsto a low pressureafter valve shifts

Two




Pressure Controls – ReducingPressure Controls – ReducingPressure Controls – ReducingPressure Controls – Reducing• Normally open, modulating device used to control the

pressure of a secondary circuit to a pressure below the main system pressure

• Different variations to meet application requirements• Used in many industrial applications

– Maintain a lower constant clamping pressure on a part when a higher pressure is needed for other functions in the circuit




Reducing Valve – Technical Reducing Valve – Technical OverviewOverview


PB*B, Pilot Operating Reducing

System 2System 1

• Port 2 inlet• Exceptionally flat pressure vs. flow characteristic• Reverse flow from port 1 to port 2 may cause the valve

to completely shut – use a separate check for reverse free flow

• If pilot flow consumption is critical, use a direct acting reducer/reliever






PR*R, Direct Acting Reducing

• Available in Series 1 through 4• Port 2 inlet• Can be used as an adjustable restrictive compensator• Damped construction provides more stable operation




Pressure Control - Pressure Control - Reducing/RelievingReducing/RelievingPressure Control - Pressure Control -

Reducing/RelievingReducing/Relieving• Normally open, modulating devices that incorporate the relief function

with the reducing function• 3 and 4 port configuration• Under a backflow condition, valve relieves pressure at port 1 through

port 3 when relief setting is met (need full capacity at port 3)• Provides a controlled pressure and a constant counterbalancing force

for bi-directional elements




Reducing/Relieving Valve – Technical Reducing/Relieving Valve – Technical OverviewOverview


PP*B, Pilot Operated Reducing/Relieving

• Similar to reducing valve with integral relief from port 1 to port 3

• Exceptionally flat pressure vs. flow characteristic• Reverse flow from port 1 to port 2 may cause the valve to

completely shut – use a separate check for reverse free flow• If pilot flow consumption is critical, use a direct acting

reducer/reliever




Reducing/Relieving Valve -- Technical Reducing/Relieving Valve -- Technical OverviewOverview

Reducing/Relieving Valve -- Technical Reducing/Relieving Valve -- Technical OverviewOverview

PR*B, Direct Acting Reducing/Relieving

• Same function as PP*B with superior dynamic response• Suitable for accumulator circuits since the absence of pilot

flow results in less secondary circuit leakage• Provides highly reliable performance in contaminated

systems or in dead head conditions• Exhibit a transitional step between reducing and relieving

—may not be suitable for counterbalancing





Reducing/Relieving Valve – Technical Reducing/Relieving Valve – Technical OverviewOverviewAdvantages

Reducing/Relieving Valve Comparison

• Fast response• Low pilot flow• Dirt tolerant• Capable of operating over a wide

temperature range• Low hysteresis• Common flow path with P/O design• Damped construction

• Wide pressure range• Low hysteresis• Low override curve• Screened orifice• Common flow path with direct acting• Low dead-band transition between

reducing and relieving• Stable performance

Direct ActingReducing/Relieving Valves

Pilot OperatedReducing/Relieving Valves

(Sliding Spool)

3 2

1

Port 1 - ReducedPort 2 - InletPort 3 - Tank

1

3 2






Reducing/Relieving Valve – Technical Reducing/Relieving Valve – Technical OverviewOverviewDisadvantages

Reducing/Relieving Valve Comparison

• Steep regulation curve• High dead-band transition between

reducing and relieving• Multiple spring ranges required to

optimize performance

• Poor response time• Constant pilot flow when operating• Contaminant sensitive in dirty

systems

Direct ActingReducing/Relieving Valves

Pilot OperatedReducing/Relieving Valves

(Sliding Spool)

3 2

1


1

3 2





Reducing/Relieving Valve - Technical Reducing/Relieving Valve - Technical OverviewOverview


PV*A, Pilot Operated Reducing/Relieving, Externally Drained

• Special version of pilot-operated reducing/relieving valve that is insensitive to pressure at port 3

• Pressure at port 4 is directly additive to the valve setting

• By controlling pressure at port 4, the effective setting of the valve can be increased over the valve setting






PV*B, Pilot Operated Reducing/Relieving, Ventable

• Special version of pilot operated reducing/relieving valve that is ventable at port 4

• Pressure at port 3 is directly additive to the valve setting

• By controlling pressure at port 4, the effective setting of the valve can be controlled below the valve setting

product/company introduction seminar pressure control cartridge valves product/company introduction...

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