Abstract: A restarting device of a pump change-over valve in a pump is provided, in which the pump includes; a pump main body 1 and a change-over valve 2. The change-over valve 2 is provided with a pair of pressure chambers 31 and 32 formed at respective ends on the back face sides of a valve body 23. The driving fluid is supplied into the chambers to induce a pressure difference to switch the direction of movement of the valve body 23. Also, the pump main body 1 is provided with a balancing valve 49 whose end portions 49A and 49B face driving chambers 4A and 5A, respectively. If the change-over valve 2 malfunctions and the pressures in the two driving chambers 4B and 5B are balanced, the balancing valve 49 is held in an intermediate position and will then induce a pressure difference between the two pressure chambers 31 and 32.

Abstract: A diaphragm pump is provided with a diaphragm defining a pump chamber and a drive chamber in the pump housing, a driving fluid is supplied to the drive chamber and a pump fluid is expelled from the pump chamber. The diaphragm pump is provided with pressure control means which, when the pressure in the pump chamber surpasses the pressure in the drive chamber neighboring the pump chamber across the diaphragm, controls the pressure of the driving fluid based upon output signals from pressure sensors in such a manner that the pressure in the fluid chamber will become higher than the pressure in the neighboring drive chamber. This makes it possible to prevent a diaphragm reversal phenomenon, wherein a diaphragm that should expand toward the pump chamber contracts toward the drive chamber instead during reciprocation of the diaphragm.

Abstract: A diaphragm assembly has a center disk in which use of a metal member is not required. The center disk comprises first and second center disk members, made of resin, embracing a resin diaphragm between them. The first center disk member has an inwardly directed inner flange on an inner peripheral wall defining a resin charging space, and the second center disk member comprises a resin-molded body, formed by charging a resin, and has an outwardly directed outer flange. A portion of the diaphragm is clamped between the inner flange and the outer flange.

Abstract: A diaphragm assembly has a center disk in which use of a metal member is not required. The center disk comprises first and second center disk members, made of resin, embracing a resin diaphragm between them. The first center disk member has an inwardly directed inner flange on an inner peripheral wall defining a resin charging space, and the second center disk member comprises a resin-molded body, formed by charging a resin, and has an outwardly directed outer flange. A portion of the diaphragm is clamped between the inner flange and the outer flange.

Abstract: A spool type valve for minimizing degradation in sealing ability is provided. The spool type valve comprises a spool 30 having land portions 36A-36E. The spool is inserted into a sleeve 20 for slidable movement along the axis thereof so as to define a plurality of fluid passages 23, 24 in the sleeve. The spool controllably opens and closes ports 21A-21E of the sleeve. Each land portion includes a slider member 38 and an O-ring 37. The slider member is divided into plural elements and is in slidable engagement with the inner wall 22 of the sleeve. The O-ring is adapted to resiliently urge the slider member against the inner wall of the sleeve. The slider member includes an annular groove 39B into which the O-ring 37 is fitted.