These Edwards WCX 500 water cooler kits connect to Edwards EXT EXT70, EXT70H/70Hi, EXT75DX/75iDX, EXT250/250H/250Hi, EXT255DX/255iDX/255H, EXT351/501 Turbo Molecular High Vacuum Pumps. They are to be mounted to the side of the turbo pump (See far right graphic above) Two riffled nozzle connectors are mounted into the water cooling block. These connectors accept 6 mm ID plastic tubing (not supplied) for the water supply lines. If you want to remove the pump for maintenance, and you do not want to break the cooling-water circuit, unscrew the fixing-screws and remove the water-cooler from the pump. 
Pipes in the water-cooling circuit may become blocked if the cooling-water contains too much calcium carbonate or if it contains particles that are too large. Corrosion of the water-cooling circuit may occur if there is too little calcium carbonate and oxygen in the water. Good quality drinking water is usually suitable. If in doubt, check the quality of your cooling-water supply and, if necessary, provide treatment and filtration. The EXT turbomolecular vacuum pump user's manual and EXT pump accessories manual is available for download in PDF format below.