Mea Hawk - 5-10 Safe Seat Adjustment

MEA INC
2600 American Lane | Elk Grove Village, IL 60007 | USA
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COMPLETE CONTROL
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MEA Incorporated | Hawk Actuator Instruction and Operation Manual
02/2018 37
A settable pressure switch, installed in the actuator fluid system, is used to provide pressure information
to the control electronics. By pumping fluid into and out of the SLA the control electronics have a
method to maintain a constant pressure on the valve seat without any direct actuator movement. Only
the actuator system pressure changes to maintain a constant seat load.
Safe Seat Operational Steps
1) While the actuator is stroking the valve towards its seat, the position feedback transmitter will
control the actuator movement. The SLA pressure switch will indicate open due to the actuator
fluid pressure being below the pressure threshold required to cause any compression of the SLA
nitrogen.
2) When the valve contacts its seat the position feedback transmitter will no longer indicate any
changes in actuator position, but the motor/pump in the HPS will continue to run.
3) With the valve on its seat, the actuator fluid pressure will increase and begin to displace fluid into
the SLA. Now the SLA pressure switch controls when the HPS motor/pump shuts off.
4) Control electronics will continue to power the motor/pump until the SLA pressure switch reaches
its target value and changes to the closed position.
5) The motor/pump are stopped and locked in position. If the control electronics detect a change in
SLA switch state it will react by running the motor/pump in the appropriate direction to achieve a
SLA pressure that is within the target deadband.
5-10 Safe Seat Adjustment
1) Install a temporary pressure gauge on one of the unused actuator SAE-6 manifold ports (1/4” hex
Allen wrench required for removal) to measure the actuator system pressure. If the Safe Seat
feature is used in the Extend/Clockwise direction of actuator travel install the gauge in one of the
unused “B” labeled manifold ports. If the Safe Seat feature is used in the Retract/Counter-
Clockwise direction of actuator travel install the gauge in one of the unused “A” labeled manifold
ports.
2) Using the HMI put the actuator into Setup Mode and set the Safe Seat Trigger Point and Safe
Seat Speed. The Safe Seat Trigger Point is the position at which point the actuator will begin to
travel at the Safe Seat Speed while monitoring the Safe Seat pressure switch.
3) Determine the appropriate Safe Seat pressure switch setpoint.
Note: The Hawk actuator is designed to produce maximum output, torque or thrust, when the
actuator fluid pressure is 2000 psi. There is a proportional relationship between pressure and