How electric diaphragm pumps can solve typical issues related to gear pumps

Specifically in low pressure applications, Graco’s QUANTM electric operated double diaphragm (EODD) pump has important advantages compared to a gear pump. The QUANTM EODD can handle abrasives effortlessly, whereas gear pumps will suffer dramatically from increased wear. Unless a gear pump is designed specifically for low viscosity fluids, it will lose efficiency when pumping such fluids. Moreover, unbalanced forces on the bearings will dramatically increase wear and noise levels.

Gear pumps

Gear pumps are used in a wide variety of industries and applications, in part because of their relatively small footprint and low weight, simple design, pulseless flow and ability to withstand high temperatures. However, they suffer from certain disadvantages that can lead to frustrating downtime, expensive repairs, and even product replacement.

• Limited operating ranges
  Because of their size, gear pumps are unsuitable for operations with higher flow rates. Each gear pump unit/size has a clearly defined, narrow operational range. Operating outside of these parameters leads to significantly reduced life and ineffective pump performance. Furthermore, the rigid design of the configuration makes it hard to adapt the pump to more demanding fluids.

• Reduced efficiency and performance when used with low viscosity fluids
  For a gear pump to effectively pump fluids at high pressure, the working parts inside must have very tight clearances. If not, very thin fluids (solvents) can slip through these tight spaces from the high-pressure (outlet) side to the low-pressure (inlet) side of the pump. Depending on the outlet pressure, the viscosity of the fluid, and the working clearances inside the pump, the slip causes a reduction in flow rate and pump efficiency. Additionally, thin fluids can lead to increased pump wear because of their poor lubricating properties. To avoid this wear, internal components made from resistant materials can be used, but the selection process of gear pumps becomes more complex and sensitive to error as a result. 

• Challenges with abrasives
  The gear pump’s close tolerances and tight spaces make it a less than ideal solution for pumping liquids containing abrasives. Abrasive particles can work their way into these tight spaces and cause accelerated wear, rapidly reducing pump performance. The resulting wear rate from pumping abrasives depends on the hardness, size, and concentration of the particles, and the operating speed of the pump.

• Unable to run dry
  Gear pumps are self-priming and can dry-lift, however, a gear pump cannot run dry for prolonged periods without destroying its expensive stators and rotors. Fluid must be present to lubricate the contacting surfaces between rotor and stator, thus dissipating the friction and heat of the pump. 

• High maintenance cost
  Gear pumps are comprised of a number of rotating parts that need precision tolerances, which makes them rather expensive to manufacture and maintain. In addition, expensive and sensitive seals can leak and require replacement.