Waterco 50mm Half Union Tail O-Ring & locking Nut.
We have listed here a image with O-Ring, Tail , and locking Ring. If you do or do not know the brand and model of the union that is on your equipment you must phone to order or email (And a photo would be great help) with information to order part..
All older and some current pumps used threaded coupling the thread in to pump is standard BSW how ever the union thread were they join maybe unique to that brand, If so you would be best advised to buy/order a complete threaded coupling.
To maintain this O-Ring use Hydro Slip (Do not use Vaseline as it is petroleum based product and will make o-rings/ rubber enlarge/stretch.