There are five parameters that do most of the work: the fluid being measured, the pipe size, the expected flow range, the operating temperature and pressure, and the output or display you need. Get those right and the field of suitable products narrows quickly. Our selector tool walks through them in order and matches you to the meters in our range that fit; for a deeper explanation of each parameter, see our Top 7 Considerations guide.

For diesel, petrol, biofuels and aviation fuels, positive displacement oval gear meters are the most common choice — they handle the relatively high viscosity of fuels well, are accurate across a wide range, and are available with hazardous-area certification when needed. Our OM Series covers most fuel applications from low to high flow. For lighter-duty or portable fuel transfer, turbine meters such as the 01A Series can be a more economical option.

It depends on the water and what you're measuring it for. For clean water at moderate flow rates, turbine meters such as the TM Series are accurate and cost-effective. For larger pipe sizes — especially in irrigation, water utilities, or anywhere site access matters — insertion ultrasonic meters like the QS200 are typically the better fit because they install without cutting the pipe. For dirty or particle-laden water, avoid meters with moving parts in the flow path; ultrasonic or electromagnetic meters handle particles better.

Material compatibility is the first thing to check. Acids and bases are corrosive to most metals and are usually best matched with thermoplastic- bodied meters; some organic compounds attack thermoplastics and need metal-bodied meters instead. Our OM Series Chemical Flow Meter uses PVDF construction suited to a wide range of aggressive chemicals. For specific compatibility, our free Chemical Compatibility Guide covers the common chemicals and the materials they're suited to.

Positive displacement meters like our OM Series oval gear range — measure flow by trapping known volumes of fluid and counting them. They handle viscous fluids well, work accurately at low flow rates, and don't need straight pipe runs to give a stable reading. Turbine meters like our G2 Series — measure the velocity of fluid spinning a rotor; they're generally lower cost, work well on clean low-viscosity fluids, but need a length of straight pipe upstream and downstream for accurate readings. For more on how positive displacement meters work, see our full explainer article.

The rule of thumb we follow at FLOMEC is to choose a meter so your expected flow rate sits between 20% and 80% of the meter's maximum capacity. That keeps the meter inside its accurate operating band and leaves headroom for peaks without damaging it, while staying above the minimum threshold where accuracy drops off. An oversized meter loses accuracy at low flows; an undersized meter risks damage and inaccuracy at peaks. The selector tool above applies this rule automatically once you enter your expected flow rate.

If the meter is installed in an area with flammable vapours, dust, or gases, then yes it's a regulatory requirement, not optional. In Australia and Europe the relevant certifications are ATEX and IECEx; in North America FM or CSA. The responsibility for compliance lies with the installer and operator. Several of our oval gear and turbine meters are available with hazardous-area-rated electronics; the selector tool will only recommend hazardous-rated options if you mark hazardous area as a requirement, so you won't be steered toward a safe-area-only meter by mistake.

A rate totaliser displays the current flow rate and the cumulative total, useful for monitoring, reporting, and general operational awareness. Our RT40 is a typical example. A batch controller adds the ability to dispense a pre-set volume and stop automatically when the batch is complete essential for filling, dosing, and dispensing applications. Our EB40 handles single-stage batching; the EB11 handles dual-stage. Both pair with our flow meters via pulse output.

Sometimes, but check three things first: material compatibility (the meter's wetted parts must tolerate every fluid that runs through it), viscosity range (a meter calibrated for water will read inaccurately on heavy oils, and vice versa), and contamination between fluids (if cross-contamination matters, you may need to flush or dedicate separate meters). For situations where fluid changes are frequent or accuracy is critical across very different fluids, separate meters are usually the safer choice. If you're unsure, contact our team with the details of your application.