GB2340555A - A seating ring for a carbon seal - Google Patents

Abstract

A sliding seal for a pump shaft has a carbon sealing ring 2 in contact with a nitrided or carbonitrided surface coating of a seating ring 1. The coating may be titanium carbonitride or titanium nitride. The coating can be applied to more than the sealing surface of ring 1, e.g. to the surfaces B, C and D and sping sockets E. Either the carbon ring or the seating ring forms the rotating component of the seal.

Description

2340555 A CARBONSEAL 51BATING RING This invention relates to Carbon Ring

Seats commonly used in pumps for water and other fluids.

The benefits of the Carbon Ring Seal have long been known as a method of sealing pumps against leakage around their drive shaft. The seal is effected by running a carbon ring in contact with a metal ring of a material which is resistant to the environment in which the seal works, The two components are held in contact with one another under spring pressure and the mating surfaces of each component are tapped to a very fine finish to prevent fluid leakage between them. One of the components is held stationary being anchored in the pump easing around the shaft and the other is fixed to the shaft and rotates with it. Either of the two components may be held stationary while the other is rotated, either orientation is effective in creating a seal.

The effects of ffiction between the two components results in a slow wear rate in either component which is taken up by the spring loading. However, this wear eventually reaches a stage where the automatic adjustment is no longer effective and major leakage takes place. At this point the pump has to be dismantled and the sealing components replaced.

According to the present invention the metalfic scat ring against which the carbon ring runs, is coated after the lapping process with a layer of Titanium Carbo-Nitride or Titanium Nitride or the Carbo-Ifitride 1 Nitride of any other element exhibiting similar physical properties. The physical properties of the above compounds have recently been applied in the cutting tool industry where their properties of extreme surface hardness and low Coefficient of Friction inhibit wear and energy lost to ffictional forces. These properties may uly be applied to a Carbon Seal Scat Ring in order to prolong its life and reduce flictional losses in the pump.

Two specific embodiments of the invention wfil now be described by way of example with reference to the accompanying drawing in which: - Figure 1 shows in section the embodiment of the invention in the case where the Seat Ring is driven by the pump shaft and the Carbon Ring is held stationary within the casing of the pump. In this case the Contact Face or all surfaces of the Scat Ring may be coated with one of the Compounds mentioned above. (There are many possible designs for the component to achieve the same effect and a typical example has been chosen for illustration) Figure 2 shows a further example where the Seal Seat Ring is part of, or an inserted component in the pump casing and the Carbon Ring is fixed in a spring loaded assembly driven by the pump shaft. In this case the contact face or all surfaces may be coated with one of the compounds mentioned above.

Refferring to Figure 1, the Seal Scat Ring 1 is mounted on the pump shaft (not shown) and driven by a pin or spur 4 which is part of the impellor.. The face A is held in contact with the Carbon Ring 2 which is set into the pump casing, by a number of springs 3 ( Contact is not shown for convenience of illustration) The Contact Face A is coated with Titanium Carbo-Nitride or Titanium Nitride or a Carbo-Nitfide 1 Nitride of any Chenal Element with the same physical properties that commend this application but which is best suited to the operating environment of the pump. The surfaces B,C and D, and the spring sockets E may also be coated with the same compound where this promotes additional operating advantages or presents a means of avoiding an increase in manufacturing costs.

Referring to Figure 2, the Seal Scat Ring 1 is set by some tneans into the pump easing and is coated on Face A with Titanium Carbo-Nitride or Titanium Nitride or the Carbo-Nitride /Nitride of any Chenfical Element which displays the same physical properties that commend this application, but which is best suited to the operating environment of the pump. The non-contact surfaces of the Seal Seat Ring may also be coated with the same compound if this is found to be convenient. The Carbon Ring 2 is set within a carrier 3 which is secured to a hub component 4 secured to the pump shaft (Not shown) and spring loaded by springs acting between components 3 & 4. These cause the Carbon Ring 2 to bear against the Scat Ring 1. (Contact is not shown for convenience of illustration) 1. A Carbon Seal seating component in the form of a metallic ring which is spring loaded in some manner and fixed to the pump shaft to rotate in contact with a Carbon Ring encircling the pump shaft and set in the pump easing, where:- (a) The Seating Ring is coated after tapping with Titanium Carbo-Nitride over its mating surfhce with the Carbon Ring.

(b) The Seating Ring is coated after lapping with Titanium Nitride over its mating surface with the Carbon Ring.

(c) The Seating Ring is coated after lapping with the Carbo-Nitride or Nitride of any Chemical Element having similar physical properties to the above materials but with particular additional properties suited to the operating environment.

Claims (1)

1. 2. A Carbon Seal seating component as ciaimed in Claim 1 which is coated

   with one of the said compounds over the whole of its exterior surfaces.

   3. A Carbon Seal seating component in the form of a metallic ring encircling the pump shaft and set into the pump casing against which a spring loaded Carbon Ring fixed to the pump shaft runs, coated as in Claim 1 and Claim 2.