Being confused and overwhelmed are perfectly normal when it comes to choosing flowmeters. From magnetic to Coriolis, to variable-area, the options are just innumerable. Yet one should understand that these meters have differences in terms of accuracy, functionality, and most importantly, price. One excellent choice is to use multi-use ultrasonic sensors that measure flow through commonly used tubes accurately and non-invasively, although it’s a bit more expensive than its counterparts. If you’re looking for a more affordable option without putting the accuracy in jeopardy, you may opt for a single-use turbine type of sensors, especially if the fluid inside the tubes is in low viscosity.
When you need to choose one between various flow meters available in the market, you have to consider the following:
- The measurement type of the flow – this includes the momentum (also known as velocity) and volumetric (mass flow measurement)
- Media – is the type of media in liquid form? Is it gassy or slurry? You need to check this and any particular condition such as particulates present and the viscosity of the media.
- Accuracy – you have to check if the readings of the meter are accurate
- Flow range – see if the minimum and maximum readings are of the required flow range of the media
- Media condition – check if the temperature and pressure of media and their conditions are more inclined to vary or remain constant
- Environment – check for any special installation instructions like hygienic installation, needing tamper-proof readings, and such.
Since you already know what to put into consideration before purchasing, here are some of the most common options for your flowmeter needs.
Single-use flow meters are often utilized in high hygiene industries and applications. These include food, biopharma, and semiconductor fabrication when it’s inadvisable to use CIP. The sensor types come along with invasive sensors which should be discarded once they come in contact with the working fluid. Aside from that, it also includes non-invasive models that do not touch base with the working fluid, making them reusable. With the extreme value placed on normal working fluids, accuracy, compatibility with the workflow, and sensor reliability are some of the prerequisites to use single-use flow meters. If you want a flow meter that offers tight accuracies, you can opt for a Coriolis type for single-use flow meter applications. Just be sure to prepare a considerable amount of money since single-use Coriolis flowmeters are more expensive in comparison to other types.
Differential Pressure Flowmeters
Differential pressure flow meters measure any changes in the media’s pressure to calculate the velocity of the flow. This type of flow meter features a laminar flow element that determines the drop in pressure using the restriction. The drop of pressure between up and downstream points is directly proportional to the flow rate. This technology works best when the whole setup doesn’t involve moving parts or when you need an extremely fast response time. These flow meters are often used in industrial applications like calculating fuel outputs (such as jet fuel or benzines), specialty chemical production, a typical water measurement testing, or in some aquafarms. They can also be utilized in labs to control and measure gas flow when mixing and separating them with the use of chromatography.
Paddle Wheel Meters
This type of meter often includes those that come along with propellers, oscillating disks (multi-jet types), and rotating paddle wheels. The component that rotates is included in the design to create a pulse when passing either an optical or a magnetic sensor. The number of pulses that it records is directly proportional to the fluid velocity at one point in the channel or pipe. These designs are perfect for those who are looking for an affordable meter with relatively high accuracy. Some versions like insertion are hassle-free and pretty easy to install while there are also other styles that are way more difficult. Paddlewheel meters are commonly seen in aquafarms, rural areas (to be used in irrigation), water/wastewater treatment facilities, and also for simple water measurement. These meters can also be seen in the oil and gas industries and also in utilities. If there is turbulent flow, this type of meter can be used with viscous fluids.
This type of meter offers better versatility and more advanced technology compared to the other types mentioned. These meters measure the shift in frequency of the ultrasonic signal sent through the fluid. There are two types of ultrasonic meters. The first one is transit-time and the other one is Doppler. Transit-time technologies depend on the difference in frequency of the forward and reverse signals. These signals are forwarded through a clean liquid to determine the fluid velocity. It is crucial to know that the fluids should be totally clean, free from solids or aeration as these things distort the sonic pulses. On the other hand, Doppler technologies use aeration or particles present on the fluid as a reflective mechanism in order to measure the velocity of the fluid. Both of these technologies are ideal when aiming to make flow profiles within a pre-existing process (if modifying piping is not an option).