Known connector seals for manholes consist of a synthetic rubber ring with an outer surface adapted to be a push fit in a hole in the concrete wall of the manhole, and an inner surface formed with a plurality of circumferentially extending inwardly directed ribs adapted to engage and seal with the outer surface of a pipe inserted through the ring into the manhole. The general dimensions of the seal and height of the ribs are selected to allow some variation in the inclination of the pipe relative to the manhole for different installations. The hardness of the rubber is also selected to allow some flexibility in the connection and the required sealing contact with the manhole and the pipe. However, the ring must be rigid enough so that once fitted in the hole in the manhole wall, it remains in place and is not displaced by insertion of the pipe, which can cause large shear forces in the ring, which might drag it through the hole. In order to further reduce the risk of displacement of the seal, it is formed with an outer circumferential collar which abuts against the outer face of the manhole, but the risk still remains that the ring and collar may be dragged through the hole, and thus care must still be taken during installation to avoid these problems.

An object of the invention is to provide a pipe connector seal in which the problem of seal displacement during installation is reduced or overcome.

This is achieved according to a first aspect of the invention by providing a connector seal comprising a ring adapted to be a push fit in a hole, one or more circumferentially extending inwardly directed ribs within the ring adapted to engage and seal with the outer surface of a pipe inserted through the ring, and a collar around the outside of the ring adapted to abut against a wall in which the hole is formed as the ring is inserted therein, characterised in that the collar is composed of a harder, less flexible material that the ring and ribs. The collar can therefore be adapted to offer the maximum resistance to deformation and displacement of the ring as the pipe is inserted through it, without compromising the required resilience of the ring and ribs so that they act as an effective seal and accommodate lateral inclination of the pipe when installed.

An additional feature of the invention consists in providing a radially inwardly directed annular flange on the ring at its leading end as inserted into the hole, the flange serving as a stop against which the end of the pipe can abut. Preferably, this stop flange is also composed of a harder material than the ring and ribs to withstand deflection by the end of the pipe; this material may be the same material as the collar.

According to a second aspect, the invention consists in a connector seal comprising a ring adapted to be a push fit in a hole, one or more curcumferentially extending inwardly directed ribs within the ring adapted to engage and seal with the outer surface of a pipe inserted through the ring, and a radially inwardly directed annular flange on the ring at one end against which the pipe can abut when inserted, the flange being composed of a harder material than the ring and ribs to withstand deflection by the end of the pipe.

The invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a break away view of a manhole wall fitted with a pipe and a connector seal according to the invention; Figure 2a is a part section through the connector seal of Figure 1 showing it assembled; Figure 2b is a part section through the connector seal of Figure 1 showing it before assembly; and Figure 3 is a part section through an alternative connector seal according to the invention that could be used between the manhole and pipe in Figure 1.

Figure 1 shows the concrete wall of a manhole 1 formed with a circular hole 2 to receive a plastics pipe 3. A connector seal 4 is provided within the hole 2 between the wall 1 and pipe 3 to form a seal. The seal consists of a ring of synthetic rubber with an outer cylindrical wall 5 that is a push fit within the hole 2. An outwardly extending collar 6 is formed at one end of the ring so as to abut against the outer face of the wall 1 when the ring is inserted into the hole 2.

A circumferentially extending inwardly directed rib 7 is formed on the inner surface of the ring so as to engage and seal with the outer surface of the pipe 3 when it is inserted through the ring from the outside of the manhole. Shear forces are exerted on the ring as the pipe 3 is inserted, but the collar 6 serves to restrain the ring against being pushed axially through the hole with the pipe.

As more clearly shown in Figure 2, the collar 6 is composed of a different material to the rest of the ring 4, typically being synthetic rubber of hardness 90 IRHD compared with synthetic rubber of hardness 40 IRHD for the rest of the ring. In this way, the properties of the collar can be adapted to make it stiff enough to resist the effect of shear forces that might otherwise deform it and drag the seal into the hole 2 with the pipe 3, whilst the properties of the rib 7 can be best adapted so as to flex with insertion of the pipe 3 and to form a good seal against its outer surface.

The seal 4 can be formed as an integral body, with the collar 6 and rib 7 composed of different rubbers by either a single stage or two stage injection moulding process. The two rubbers may also be different colours so as to enhance the appearance of the seal and assist identification amongst similar seals not incorporating the invention.

Figure 3 shows an alternative embodiment of the invention which is similar to that of Figures 1 and 2, but which has the further addition of an annular end stop 8 for the inner end of the pipe 3. The end stop 8 is also preferably made of a harder material than the rib 7, and may be composed of synthetic rubber with a hardness 90 IRHD like the collar 6. A portion 9 of the end stop forms a tubular extension of the ring and is formed with an inwardly extending flange 10 at its end having an abutting face against which the end of the pipe 3 will engage.

It will be appreciated that in yet a further embodiment of the invention, the connector seal may incorporate an end stop 8 of a different material to the ring 4, as shown in Figure 3, except that the collar 6 is composed of the same material as the ring 4 and rib 7.