Versatility is key for double-diaphragm pumps

With the new European ATEX Directive in force, now could be the time to change from centrifugal to double-diaphragm pumps.

Roban double-diaphragm pumps have become so advanced that many engineers are now making the change from traditional centrifugal to double-diaphragm pumps.

Positive displacement double-diaphragm pumps bring processors considerable advantages over centrifugal pumps, chiefly because of their sheer versatility in different processing applications.

They also score higher marks in other areas, notable their ability to move viscous liquids efficiently through a processing system, their compact size, their capacity to handle high differential pressures and achieve continuous flow performance regardless of the differential pressure condition.

Recent independent industry research and the latest ATEX legislation which became law on 1st July 2003 has highlighted double-diaphragm pumps as both the largest and, although the technology has existed for over 40 years now, also the fastest growing area within this positive displacement sector.

What makes the Roban double-diaphragm pump such an increasingly attractive choice for processors is largely down to its versatility in operation.

The double-diaphragm pump can handle a vast range of products and product viscosities, extending even to soft suspended solids.

At the other end of the spectrum, the double-diaphragm pump is capable of low shear pumping, minimising the effect of the pumping action on shear sensitive materials.

Roban double-diaphragm pumps are also extremely versatile in handling the different flow and pressure requirements of specific applications.

Simply by controlling the air inlet valve, engineers can change the pump flow rate from zero to maximum flow.

This eliminates the need to install expensive variable speed drives or bypass systems and removes the requirement for critical pump selection.

With such easy flow control, one double-diaphragm pump can fit a broad range of applications and capacities.

Roban Double-diaphragm pumps even offer the capability to run dry indefinitely without causing any damage to the pump and they are also completely self-priming from a dry start on suction lifts.

The air pressure to the pump can be easily regulated as required to control pumping pressure.

Using a Roban double-diaphragm pump means that the maximum pump pressure will never exceed air inlet pressure and a consistent pumping rate can be maintained even under fluctuating pressure head conditions.

Using compressed air as the power source provides other pumping advantages.

It ensures Roban that double-diaphragm pumps are less expensive to install than electrically powered pumps.

Primarily, there is no need to install expensive motor and control equipment with double-diaphragm pumps.

Connection by air hoses to a compressed air supply are all that's required.

As a result, Roban's ATEX certified double-diaphragm pumps present no explosion or electrical risks in hazardous environments - and so, there is no additional requirement for installing explosion relief systems or spark proof boxes.

For added insurance in these hazardous environments, Roban double-diaphragm pumps uses spill containment options which can be installed very cost-effectively.

Roban Pumps rupture protection systems feature product capture and various alarms can be activated either to shut the pump down, sound a horn or send a signal to a computer, if required.

Once operational, diaphragm pumps bring major savings on running costs.

The power consumption is in direct proportion to pumping performance so that no energy is wasted.

In addition, the pump discharge valve can be closed for as long a period as required without any power being consumed, any resulting heat build-up or any movement which would create wear on the pump itself.

Yet as soon as the valve is opened, discharge flow starts immediately.

In the early days, air-operated double-diaphragm pumps had a reputation for mid-position stall, but with the development of the anti-stall spool valve, this problem has been eliminated.

Another area where air-operated double-diaphragm pumps have not been traditionally used, due to the pulsating flow characteristics, is when a smooth flow is required, particularly where metering or instrumentation is installed.

Again this has been overcome with the latest developments in inline pulsation dampers.

Wear and tear is an important issue with all types of process pumps.

Because of their simple design, ordinary double-diaphragm pumps have no shaft seals or packing glands which can wear and require frequent maintenance.

And, with no impellers, rotors, pistons, gears or vanes to wear out and complicate matters, processors can be confident that pumping efficiency will not deteriorate over time.

Roban air-operated double-diaphragm pumps are available in a range of sizes, specification options and choice of materials to suit different processing requirements ensuring that the double-diaphragm pump is perfectly well suited to numerous different applications within the chemicals, paints, food, brewing, toiletries, cosmetic, pharmaceutical and other process sectors.

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