GEMU Model 684 Industrial Diaphragm Valve


The GEMÜ 684 diaphragm valve features a compact design and high flow performance and it is the ideal Pneumatic Valve for controlling and/or shutting off of practically all kinds of neutral or corrosive liquid or gaseous fluids, with or without solids in suspension. Sealing is effected by a flexible diaphragm, which when fully closed seats against the weir under pressure from the compressor to provide a cushioned, positive driptight shutoff. The valve is operated by a maintenance-free diaphragm actuator, which can be controlled by any inert liquid or gas. When the GEMÜ 684 is fully opened, it has the largest flow passing through area than any other typical flow controlling valves. The flow to be controlled   only contacts the body/lining and the diaphragm.


  • Bubbletight shutoff. The diaphragm will accommodate itself to grit, rust, slurry or fibrous particles present in the line.
  • Good throttling of highly corrosive or abrasive media when the valve is equipped with a positioner.
  • Lower initial price. No special alloy working parts are required.
  • Long trouble-free operation and lower operating cost. High operating efficiency on account of low pressure drop and streamline flow.
  • Long life rugged maintenance-free actuators.
  • No stuffing box to repack or packing gland to adjust.
  • Lower maintenance cost/easy in line maintenance. The diaphragm is replaced quickly and easily without the need to remove the body from the pipeline.
  • Possibility of replacement of other diaphragm valves (other manufacturer) already installed, as there is a wide range of standards and types of connections.
  • The valve can be installed in any position in the pipeline and used in both directions of flow (bidirectional).
  • Wide interchangeability of bonnet assemblies and diaphragms.
  • Out and out durability and efficiency.


Nominal Sizes: 1/2″3/4″1″1-1/2″2″

Connection Type: 125# Flat Face Flange, 150# Flat Face Flange, 150# Raised Face Flange Serated, 150# Raised Face Flange Smooth, Flanged ANSI class 125/150 RF – length EN 558-2 Series 1, ISO 5752 Basic Series 1, Schedule 40 Socket Weld, Threaded NPT

Valve Body Material: 316 Stainless Steel with PFA Lined BodyCast Iron – ASTM A-126 Class B Body, Ductile Iron with Butyl Lined Body, Ductile Iron with Hard Rubber Lined Body, Ductile Iron with Hypalon Lined Body, Ductile Iron with Neoprene Lined Body, Ductile Iron with PFA Lined Body, Ductile Iron with Polypropylene Lined Body, Ductile Iron with PVDF Lined Body, Ductile Iron with Silica Free Soft Rubber Lined Body, Ductile Iron with Tefzel Lined Body, Investment Cast 316 Stainless Steel Body

Diaphragm Material: Buna-N, Butyl, EPDM, Hypalon, Natural Rubber Silica Free, Neoprene, PTFE/EPDM, PTFE/Viton, TFM/EPDM, TFM/Viton, Viton

Control Function: Pneumatic Air to Air, Pneumatic Normally Closed, Pneumatic Normally Open

Actuator Size: 1A3, 1AD, 1AF, 2A2, 2A3, 2AD, 2AF