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DE-STA-CO
has a line of Control Valves designed and manufactured
so precisely that there is virtually zero leakage, making them
ideal for
constant pressure hydraulic workholding systems. Valves with internal
leakage (such as spool valves) are not appropriate for use with
DE-STA-CO pumps and pallet valve systems.
There
are 3 Types of Control Valves -
Directional
Control Valves
Pressure
Control Valves
Flow
Control Valves
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Directional Control Valves
Available in many versions, each of these valves is capable of operating
double- or single-acting spring return systems.Mounting configurations
available are remote mounted and manifold mounted, with manual
operation.
Manually Operated Valves are
used in applications where the
valves can be mounted near the
operator on the fixture, pump, or any
convenient location at the workstation.
The Electrically Operated Valve is ideal for
systems requiring push-button simplicity or
automated systems where the valve is
controlled by machine logic instead of the
operator. Since it’s controlled by an
electrical signal, it can be mounted in any
convenient location and need not take up
valuable fixture or workstation space.
All Remote Mounted Directional Control Valves are installed
by the
pump or pressure port (labeled “P”) to the pressure source
and the
return or tank port (labeled “T”) to the return line.The
outlets or work
ports (labeled “A” and “B”) are connected to
the component or system to
be controlled.
In single-acting systems, the valves are used as three-way valves.
One
port, A or B, is plugged and the other is connected to a single-acting
actuator or system. In one handle position, the port to the actuator
will be
pressurized and the plugged port open to the reservoir. In the other
handle position, the actuator will retract because that port is
open to
the reservoir.This pressurizes the remaining port, but since it’s
plugged, the pump will build pressure and shut off.
In double-acting systems, these valves act as four-way valves: ports
A
and B are connected to a double-acting actuator or system. In handle
position A, port A is pressurized and port B is open to the reservoir.
Handle position B pressurizes port B and port A is open to the reservoir.
Shifting the valve will cause the actuator to alternately extend
and retract.
Carefully review check valve requirements on each product selected.
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Pressure Control Valves
Two types are available for specialized workholding systems –
sequence
and pressure reducing. Both are available in manifold and conventionally
mounted styles.
Pressure Sequence Valves control the order of events
within a hydraulic system by directing pressure
into two circuits in a pressure-controlled
sequence. For example, this allows
clamps to be actuated before work
supports are locked.
Initially, the valve is closed. Oil flows
to the primary circuit until pressure reaches
the valve setting.The valve then opens to deliver oil
to the secondary circuit while holding pressure on the primary circuit.
Once secondary and primary pressures are equal, the pressure
increases uniformly in both circuits.
This valve is installed by connecting the pressure port (labeled
“P”) to a
tee in the portion of the circuit to be actuated first.The part
of the circuit
to be sequenced later is connected to the outlet port (labeled “A”).
The vent port must be open to atmosphere for proper operation.
Pressure Reducing Valves are designed to reduce the maximum
pressure in a portion of a hydraulic circuit – the need for
a separate
power source for each pressure level is eliminated.The valve is
open
from the inlet to the outlet until a pre-selected pressure is reached,
at
which point the valve closes to limit pressure in the secondary
circuit.
Valve seats and poppets are precision ground, assuring virtually
zero
leakage and eliminating the need for a case drain line.
This valve is connected “in line” with the circuit requiring
the reduced
pressure.The inlet or pressure port (labeled “P”) is on
the high pressure
side.The outlet or reduced pressure port (labeled “A”)
is connected to
the lower pressure circuit.The drain or tank port (labeled “T”)
is
connected to the power source return line if necessary. Ordinary
pressure limiting valves close when their pressure setting is reached.
Once closed, it will not re-open until system pressure is released.
Even
minor leakage in the system can not be made up. DE-STA-CO’s
pressure reducing valve uses a balanced poppet design which
will re-open any time flow downstream is required.
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Flow Control Valves
The types of flow control valves available from DE-STA-CO are
pilot operated check valve and needle-type flow restrictor valves.
DE-STA-CO’s Pilot Operated Check Valve offers a unique
poppet seal
design making it ideal for pallet applications or other specialized
control
circuits where zero leakage is essential. It can be used in any
application
where pressure must be maintained in a portion of a circuit until
a separate
pilot signal opens the valve and allows free flow in the reverse
direction.
When the port labeled “INLET” is pressurized, hydraulic
fluid can flow
freely into the valve, leaving through the port labeled “OUTLET”.
Pressurized fluid at the outlet port cannot flow back into the valve
unless
the port labeled “PILOT” is pressurized to open the valve
allowing
reverse flow.
Needle Valves are multiple-turn flow restrictor valves which
provide
finely adjustable flow control for components or circuits requiring
reduced
flow rates.They are also used in some non-critical sequencing
applications where restriction in part of a circuit will tend to
cause the
actuators in the remainder of the circuit to operate first.
Needle valves are available that a) restrict flow in both directions,
or b) restrict flow in one direction through the use of an internal
free-flow check valve.
Valves without the free-flow check are typically used in a part
of a circuit
where there is flow in only one direction.They can also be used
in
double-acting circuits where restriction is desirable in both directions.
Valves with the reverse free-flow check are most effectively used
in
single-acting circuits where the actuation speed must be reduced
without
affecting the system return time.
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