Abstract: A chemical injection system has a pump and an actuator connected to the pump. The actuator further comprises a first sensor for sensing a deactivated state of the pump; a second sensor for sensing an activated state of the pump; a computer connected to the first and second sensors and the actuator; and an interface connected to the computer, to receive commands from, and to transmit data to, a control point. The computer further comprises a stored program. The stored program contains instructions to energize the actuator to cause the pump to dispense a pre-determined quantity of chemical and to verify that the pump has actually operated to dispense the pre-determined quantity of chemical.

Abstract: A fluid power unit has a cylinder in a housing, a piston slidable in the cylinder and dividing the cylinder into a retract side and an extend side, and a two-position control valve. The control valve has a spool and first and second pilots. The position of the spool is responsive to the first and second pilots. There is a retract poppet valve in the retract side of the cylinder, and an extend poppet valve in the extend side. The retract and extend poppet valves are biased to a closed position. The retract poppet valve is in a fluid path between the retract side and the control valve; the extend poppet valve is in a fluid path between the extend side and the control valve. The alternate movement of the piston in the cylinder alternately opens and closes the poppet valves, The circuit connects the poppet valves to the pilots and alternately applies and releases pressure to the pilots, causing the spool of the control valve to shift and apply inlet pressure to the piston on alternate sides.