Metering pumps are used in almost every segment of an industry to meter, inject, transfer, dispense, sample, or proportion fluids. Metering pumps and dispensers are used in a variety of applications, including chemical process industries (CPI), laboratory, OEM analytical instrumentation, and automated medical diagnostic equipment.
With such an array of applications it can be difficult for customers to know which pump is best for their industry. These important considerations can help you get started on selecting the perfect pump.
1) Flow Rate or Dispense Volume – The first parameter to consider when selecting a metering pump is the required pump capacity. Looking at a manufacturer’s flow capabilities will immediately narrow the choices of the metering pumps that meet the flow criteria.
When considering options for metering pump selection, in most cases, you would want to select the metering pump which has a capacity closest to the maximum flow rate required for the application. This generally will provide a pump that will have the highest accuracy for that application.
2) Fluid Characteristics – Assuming you now have several metering pump options that meet your flow rate requirements, it is important to examine the physical and chemical characteristics of the specific fluid being pumped.
Physical characteristics include viscosity, density, suspended solids, aeration, lubricity, etc. The physical properties directly relate to how the fluid moves through the pump or what is considered fluid dynamics and affects the mechanical operation of the pump. In general, the higher the viscosity, the more drive torque is required. The pump inlet and outlet orifices, as well as the connected plumbing would need to increase as well. Pumping slurries require similar requirements as viscous fluids, but additionally slurries can cause mechanical abrasion to internal pump components.
Chemical properties typically considered deal with corrosion effects of the fluid on the wetted parts of the pump. Strong acids & bases, as well as fluids with solvent properties require wetted parts that have chemical resistance to the specific corrosive fluid. Published corrosion resistance charts should be referenced to ensure compatibility between the fluid type and the wetted pump parts. Additional information required when referencing corrosion resistance charts is the fluid concentration (pH and/or percentage) and fluid temperature. If possible, referring to MSDS Data Sheets or contacting the fluid manufacturer can also help with selecting the best pump material.
3) Pressure – When considering pressure, it’s important to know both the differential pressure (difference between the inlet and outlet), as well as the overall system pressure. Not only does the pump need to have the ability to pump against the outlet pressure, but also be rated to withstand the overall system pressure plus a margin for safety.
4) Temperature – Fluid temperature is an important factor in determining pump compatibility. As mentioned above, fluid temperature can affect the corrosive chemical properties. But, additionally, fluid temperature will affect the mechanical components and integrity of the pump. This is especially true of pumps that use elastomers and fluorocarbons (PVDF, Teflon®) which lose structural integrity as temperatures increase.
5) Accuracy and Precision – Inaccurate pumps can generate waste and incur extra costs. Fluid Metering pumps accuracy is held from microliters to the full flow range and output does not change more than ± 1% of set value. Check our Pay back Calculator to see how long it will take for a Fluid Meter pump to pay for itself.
In addition to these 5 essential steps it is also very important to review special application requirements when selecting the correct metering pump for your application. Some of these include:
- Sanitary Design which may require special agency approvals (FDA, 3A, etc.)
- Intrinsically Safe or Explosion Proof for use in hazardous areas
- Water resistant, water proof, or submersible usually NEMA rated
- Ambient Temperature – Will the pump and/or control electronics be exposed to extreme cold temperatures in an outdoor environment or extreme heat in a factory setting? This is more of environmental or ambient temperature requirement rather than the temperature of the process fluid
After over 55 years of providing dispensing and metering solutions, FMI has archived hundreds of applications in our comprehensive searchable database. We can search by fluid, application specs, industry, etc. and most likely be able to tell you when, how, and what pump was used to do it before. FMI metering pumps and dispensers have been used for industrial automation, medical instrumentation, laboratory R&D, chemical process, pharmaceutical packaging, mining, alternative energy, water treatment, environmental monitoring, food processing, and much more.
For assistance with a specific application or for custom design support, use our “Live Help” at http://fluidmetering.com/livehelp.html, for a direct connection to Fluid Metering’s application experts, or use our secure Application Request Form to provide us with details of your project. One of our specialists will contact you to target a solution.