The Disposable Flowmeter is a niche-product of which meanwhile multiple variants have become available in the market.
Diversity in the available solutions is good, since there is no universal solution that only has advantages.
Depending on your demands and wishes, it can be determined which type of single use flowmeter will suit your application best.
Below I like to menstion some aspects that are to be considered in the selection-process.
Demands and wishes
When starting to think about specifications, a number of aspects will come to your attention.
In this phase it is useful to separate the absolute demands from the more ‘soft’ wishes. Doing this will help you in a later stage where you might be forced to choose between possible solutions.
An example is de flowrange of the instrument. The current application will hae a lower limit and an upper limit. If the lower limit is a demand, please store it as such in your list. If a higher max flowrate may be useful in the future, write it down as a wish. It may very well be that a high flowrate instrument is available, but doesn’t offer the required accuracy in it’s lower measuring range.
Each type of instrument measures differently and with a different deviation.
Each method has in it’s physical form a maximum achievable accuracy. Deviation from the nominal measured value results in a process-deviation.
It’s up to you to determine wich level of accuracy is required.
When comparing, please be advised to ensure the unit of measure in which accuracy is expressed.
A 1% deviation of Full Scale (FS) can be completely different from a 1% of Measured Value (MV). This topic is further detailed in another chapter.
A high-end instrument such as Coriolis or Ultrasonic will prove it’s accuracy on the certificate of calibration.
The socalled ‘wetted parts’ are all the internal parts of the disposable flowmeter that actually are in contact with the measured medium, zijn de onderdelen van het instrument die met het medium in aanraking komen.
In the example of a turbine-meter these are: housing, turbinenbladed, shaft, bearings and possible sealing material.
An electromagnetic flowmeter already has less wetted parts, but will always have a housing, metal electrodes and seals.
Coriolis- and ultrasonic flowmeters often have just one wetted part, the housing itself.
In the case of MIB Flowmax, the wetted material is an approved and resistant plastic. Here’s an example of a Suppliers certificate.
Gaps and dead-space
The main reason to go for a single use / disposable component is cleanliness or purity. Contamination in any form or shape is absolutely unacceptable.
The form and shape of your instrument affects the risk of contamination.
Gaps between components are potential hiding places for bacteria and other unwanted particles or even molecules. Presence of sharp edges and corners or bearing points means an increase of risk.
Free-bore instruments are always the better option, electromagnetic, Coriolis and Ultrasonic have a comparable ranking.
When considering all details like number of gaps, surface roughness and dead-space, the all-plastic one-piece housing of the ultrasonic disposable flowmeter scores best.
The financial aspect will remain an aspect in the total ranking.
In cases where cost is the most important factor, a turbine-meter will be the better option compared to more advanced instruments.
Bio-pharmaceutical processen have risks which financially have hundreds or thousands times the impact of the instrument value.
Those riscs can partly be prevented by selecting the right equipment for your process.
A clean instrument, free of moving components and with only one wetted part, which reliably measures with high accuracy -even in pulsating flow- is always good value for the money!
Save money by replacing only the neccessary
In MIB‘s strive to always do the maximum possibe in your advantage, also the cost-impact has been considered.
By designing the instrument with a separate measuring tube, the wetted parts can be exchanged whilst leaving the electronics in place.
In fact it is a single use flowmeasuring tube rather than a single use flowmeters. By providing factory-calibrated measuring tubes, including a dongle with the unique calibration details, you’re ensured of the original accuracy.
In case of a process-change, the nominal bore-size of the measuring tube can be replaced by another size and the matching dongle takes care of the accuracy.
This smart design is freely available and saves you €1.500,= per exchange!
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