Abstract: A vacuum head for cleaning underwater surfaces has a depending skirt; the head, on its underside, has a brush depending therefrom with means on the underside to support the brush, which means is spaced inward of the skirt and is provided with apertures located between the brush and the head.

Abstract: A differential pressure relief valve formed of a housing having first and second chambers sealed from the atmosphere and separated by an annular diaphragm with the chambers and the annulus of the diaphragm traversed by a moveable sleeve. The first chamber communicates to a primary pressure source through a first channel in the housing and the second chamber communicates to a secondary pressure source through holes provided in the sleeve and then to a second channel in the housing. The end of the sleeve protruding from the second chamber is engageable with a seat in the housing. The arrangement is such that when the primary pressure exceeds the secondary pressure by a predetermined amount, the end of the sleeve protruding from the second chamber engages the seat but if the primary pressure does not exceed the secondary pressure by the predetermined amount, the end of the sleeve does not engage the seat, and fluid escapes from the source through the second channel and communicating sleeve, past the seat.

Abstract: A balanced valve disc and seat structure has a hollow valve disc engageable with the seat and pressure responsive means supported in the disc; the pressure responsive means divides the hollow valve disc into separate first and second chambers with a first aperture in the disc communicating with the first chamber and a second aperture in the disc communicating with the second chamber. A plunger has one end secured to the pressure responsive means with the other end of the plunger extending through the second chamber and the valve seat with means engaging the other end of the plunger when the first chamber has a higher pressure than the second chamber.

Abstract: A thermostatically controlled valve for heated fluid flowing through a conduit has a valve seat and cooperating valve mechanism to permit the flow of fluid through the seat; a housing, open at one end, is secured to the conduit at the other end over the valve mechanism. A sensor, secured in the open end of the housing, is responsive to change in ambient temperature of the air above the housing and the sensor operates a plunger which acts on the valve mechanism to regulate the flow through the said seat. Thermal shielding means are provided in the housing between the sensor and the valve mechanism to prevent heat from the latter affecting the sensor and vents are provided in the housing below the thermal shielding means to allow air heated by the valve mechanism to escape to atmosphere.

Abstract: A first and second check valve operated independently in a conduit section and having first and second valve stems on a common axis with first and second valve seats and cooperating normally disposed valve plates with the valve stems inclined away from the direction of flow, the second valve seat being larger than the first valve seat and the lowermost level of the second valve seat is at least below the lowermost level of the lift of the first valve plate with a single removable cover on the conduit section for securing the check valve in position.

Abstract: A thermostatic control valve for regulating the supply of fluid through a conduit includes in combination a valve plate and seat in the conduit, the valve plate having a valve stem extending outwards of the conduit with the valve stem having a spring exterior of the conduit to move the plate away from the seat and a housing secured to the conduit with a retractable plunger in the housing operative on the valve stem. The plunger is contained in a casing having means responsive to temperature change to move the plunger towards the seat. An interior member is threaded in the housing and removable means are used for attachment to the interior member to rotate it in the housing, thus providing adjustment. The control valve is secured to the conduit through a washer having a pawl which engages with ratchet shaped teeth of a ring secured in the control valve.