seal on two lip parts 27 and 28 and ensures less gap with the connector exteriorly to collect dust and dirt an oversleeve for example of explosion suppressing kevlar can be provided to slip over the flexible connector and if desired extend over the spigot 8 9 at each end thereof if desired the oversleeve can be clamped for example by any clamping method onto the surface 29 or the oversleeve can be left free but with sufficient lapping to ensure adequate explosion protection fig3 a shows the flexibility of the connector but even though it is connected attention should be paid to fig3 a through 36c u00f8 inside diameter of both spigot and connector ends in mm u2014 options suggested being in table 1 al separation of spigots in mm cl connector length in mm h is spigot or ferrule head retention profile length e g preferably about 35 mm t is spigot or ferrule tail length e g preferably about 52 mm suitable internal diameters for the tail and inside of each end of the connectors is preferably one of the following from the table for a diameter u00f8 e g which can be any of those shown in the table the distance al between the spigots relates to a connector length cl as follows spacing al for in line static equipment as shown in fig3 a should be the connector length cl minus 10 mm for the off set equipment of fig3 b the spacing al should be the connector length cl minus 20 mm for vibrating equipment the spacing al should be the connector length cl minus 40 mm can be provided with better resistances to internal explosions than conventional flexible couplers in this specification where reference has.