KNF Diaphragm Vacuum Pump UN726.1.2 FTP

Materials needed: Proper replacement kit(s), Roll of Teflon® tape, Marking pencil

Tools Required: 4 mm socket key wrench, 20 mm open-end wrench, Slotted-head screwdriver

Disconnect the pump from electrical power. For double-head pump, sketch the position of interconnecting tubes and fittings for reassembly later. Remove them by undoing nuts with the 20 mm wrench and carefully pulling tubing from fittings.

Mark the position of the pump head-plate A, intermediate plate B and crankcase C relative to each other by drawing a line on the edges with a pencil or other marker to assure proper re-assembly.

Remove the four socket screws D with the 4 mm socket key and remove the headplate A. Lift off the valve plate E. Note the positioning of the valveplate in relation to the valve ports on the intermediate plate.

Remove the intermediate plate B and housing cover F.

Unscrew the old diaphragm G by turning it counterclockwise using both hands. Do not use tools. Take care not to lose any spacers H positioned between the diaphragm stud and connecting rod, as the exact quantity must be reassembled later for proper pump operation.

Place the same quantity of spacers as removed in step 5 above onto the threaded stud of the new diaphragm. Carefully screw the new diaphragm G into the connecting rod J. Tighten firmly using both hands only. Do not use tools.

Turn the counterweight K until the diaphragm is in mid-position (flat across). Carefully center the diaphragm over the compressor housing C, or over the head spacer ring L. Note: Only double-head pumps are supplied with a head spacer ring.