They are available in cast iron, stainless steel, various plastics including PTFE and aluminium. They are intrinsically safe and can be supplied with ATEX certification.

Other features include:

• Good dry running characteristics
• Can run against a closed valve (when pump pressure equals air supply pressure they just stop, then re-start when the blockage clears
• Can be up to 97 per cent efficient
• Good self-priming capabilities
• Good solids handling capability
• Will handle a wide viscosity range
• The AODD is half the price of a Lobe or Twin Screw pump
• Graco is a reputable, global company

Set-up of the pump is straightforward, involving a quick exchange of the diaphragm. After the piston flange is dismantled there is no zero-resetting.

Benefits of the pump are as follows:

• Robust and reliable construction
• Minimum amount of spare parts required due to highly efficient design
• Quick and easy setup of a twin pump by installing a second dosing unit (with the same or a different capacity) onto the driving gear
• Symmetric design allows the piston flange to be mounted on either side of the dosing units
• Simple conversion. By adding four stud bolts, the metering pump can be converted from manual to electric stroke length control
• For operation, high standard multi-range motors (220-240/380-420 V, 50/60 Hz) are used for a wide range of applications and short delivery times for all pump types
• Integrated safety pressure relief valves (test certified by TÜV) are standard for all our pumps which protect the pump in the event of overpressure or cavitation