Patent GB-334540-A (GB)
Title: Improvements in or relating to apparatus for controlling the direction of the draught in air-conditioning or ventilating systems
IPC: F24F11/00
Filed: 1929-03-05
Abstract: 334,540. Hall & Kay, Ltd., Hall, J. H., Kay, P., and Hall, S. March 5, 1929. Controlling ventilation; ventilating-pipes, arrangement of; forced ventilation; valves and valve apparatus, actuating.-The direction of the draught in a theatre &c. is changed by stopping a plenum fan and by a system of dampers connecting an auxiliary duct to a continuously operating extraction fan; the controlling means may be associated with means for raising and lowering the safety curtain. Normally a plenum fan 10 drawing its supply from the outside atmosphere and/or a return duct 12 leading from extraction openings in a duct 14 at the lower level of the auditorium 5, discharges into the upper level of the auditorium through inlets 18 in ducts 16, 17 whilst an extraction fan 19 extracts air from the upper level of the stage area 4 and discharges to the atmosphere. The direction of the draught is reversed by stopping the fan 10 and also an extraction fan 13 in the return duct 12, closing a damper 25 in the duct 16 and opening a damper 24 in an auxiliary duct 23 leading to the fan 19 from an opening in the upper level of the auditorium. A damper 15 serves to regulate the air drawn from the atmosphere and/or from the return duct by the fan 10. Pneumatic motors 26, 27, 28 controlled by the movement of the safety curtain or by valves' 34 arranged in suitable parts of the theatre operate switches of the electric motors for driving the fans 10, 13 and for operating the dampers 24, 25. Normally when the fire curtain is raised, a main control valve 31 will admit air under pressure from an air reservoir 29 to pipes 35, 36, 37 leading to the, motors 26, 27, 28, and will open pipes 38, 39, 40 to exhaust, and so actuate pistons 26<a>, 27<a>, 28<a>. The piston 26<a> operates a trip switch 43 to switch current on to rheostats 41, 42 and also operates the latter to start the motors that drive the fans 10, 13. The pistons 27a, 28<a> operate to close the damper 24 and open the damper 25 respectively. When the fire curtain is lowered the pilot valve 33 is moved to the left by gearing, thus admitting air under pressure by pipes 46, 47a, 47 from an air reservoir 29 to the diaphragm chamber 48. The distension of the diaphragm 50 causes a spindle 50<a> to rock lever 51 to reverse the valve 31, whereupon the motors are reversed to stop the fans 10, 13, open the damper 24 and close the damper 25. If, while the system is operating normally, any of the bye-pass valves 34 should be opened, air under pressure will pass from the pipe 46 to the diaphragm chamber 48, and the motors will he reversed. For operating the rheostats 41, 42, the piston rod 26b is pivoted to members having U-shaped extremities, and provided with rollers 53<h>, 53<i> operating in guide tracks 54, 54<a>. As each member is moved outwards, it is held in a raised position so that its short limb engages the rheostat lever; at the end of this movement the members fall into the lower runs of the tracks, and so permit the rheostat levers to fly back. When the current is shut off, the long limbs engage the levers during the return movement if the levers have failed to fly back. Specification 333,263, [Class 8 (ii), Air and gases, Treating &c.], is referred to.