Abstract: A cartridge seal having a sleeve for fitting over a pump shaft and, at one end region of the sleeve, a stationary seal whose floating component is biased towards its static component. The cartridge further includes a member longitudinally spaced from the seal, which member and the stationary seal are moveable longitudinally relative to one another. The floating component is biased away from said member and towards the static component, means being provided to limit separation of said member and the stationary seal. The invention therefore provides a complete mechanical seal in one cartridge.

Abstract: A mechanical seal 30 is disclosed comprising a sleeve 32 which is adapted to be affixed to the shaft 34 of a item of mechanical equipment, together with a rotary component 42 which carries a rotary seal face 44. Two O-ring grooves 46, 48 are provided on the sleeve 32, the first 46 being remote from the rotary seal face 44 and cut somewhat deeper into the sleeve 32 than the second 48. The rotary component 42 has a first region 50 remote from the rotary seal face 44, the inner surface of which has a relatively small diameter and a second region 52 between the first region 50 and the rotary seal face 44, the inner surface of which has a larger diameter. A pair of O-rings 54, 56 are located in the O-ring grooves 46, 48 and seal against the inner surface of the rotary component 42. The net thrust, if any, acting on the rotary component 42 and hence on the rotary seal face 44 tends to close the seal face irrespective of whether the barrier fluid pressure is in excess for less than the product pressure.