ELECTRIC OPERATIONThe opening of the directional valve is accomplished byfitting the directional valve with an electric control head.Figure 5 shows the assembly of a pressure-operateddirectional valve and an electric control head in itsclosed position.When the Halon 1301 being discharged reaches theclosed valve, it enters an auxiliary annular cavity aroundthe main valve seat. Figure 5 shows the location of thepressurized gas which is dead-ended against the pilotseat. Once the pilot seat is depressed by the electriccontrol head, the pressurized gas generates a force onthe piston which has been compressing the spring andholding the valve closed. The valve, as a result of thispressure, opens instantly.The valve design is unique in the fact that it is an in-linetype having very little pressure drop across the seat.Figure 6 shows the position of the parts of the valvewhile the valve is open during operation.ELECTRIC CONTROL HEADThe electric control head (see Figure 7) is available foruse with various voltages. When heat due to fire causesthe detector to close and complete the electric circuit,electric energy operates a solenoid in the electric controlhead which trips a lever mechanism releasing a spring todrive the plunger forward to open the pilot seat. Theelectric control head can be operated from a remotepoint utilizing manually operated switch cases.This control head includes an important maintenancefeature: it can be removed from the cylinders for check-out. Visual checks can be made to verify actuation bymanually operating the system.EXPLOSION PROOF ELECTRIC CONTROL HEADThe explosion proof electric control head is availablewith various voltages. It is suitable for use in Class 1,Groups C & D type environments as specified in theNational Electrical Code.The explosion proof head like the electric head isoperated by the movement of the solenoid that trips alever mechanism releasing a spring that drives a plungerforward to open the pilot seat. See Figure 8.CONTROL HEAD INSPECTIONAfter operation, it is not necessary to replace any controlhead parts. The control head is reset by using ascrewdriver to turn the reset shaft from "released"position to "set" position. See Figure 9. The head isalso fitted with an emergency manual control. Themanual control can be utilized by pulling out the safetylocking pin, and then operating the lever.An important advantage in the design of the control headis that visual inspection is all that is needed to determinewhether the head has operated. If the reset shaft hasrotated to "released" position then the head hasoperated.In fact, no replacement parts are required to reconditiona discharged system at recharge.7
Integrated Publishing, Inc. - A (SDVOSB) Service Disabled Veteran Owned Small Business
