Why do Alicat Scientific mass flow meters offer true mass flow measurement?

Flow  |  Monday, 20th February

We’ve recently received questions from customers confused by Alicat Scientific’s use of flow rates on their range of mass flow meters and controllers. Here we set out to determine what ‘true mass flow’ is and what the benefits of this measurement are.


For companies and engineers that need to measure flow rate, improving the speed and accuracy of results can have a big impact on operations, allowing personnel to focus on other business areas, and freeing up time. Knowing you can rely on a mass flow meter, gives you confidence in the accuracy of the information you are receiving.

When you select the right instrument, the measurement of mass is easily and efficiently managed. This enables companies to concentrate on other aspects of the business that transform operations, such as boosting production capacity, creating a brand differentiator, and improving the speed of flow audits.

Volumetric versus molar versus true mass

There are multiple ways of measuring flow rates of gases and other fluids. Each method has its own applications and unique technical challenges as additional levels of complexity are added to the measurements. Among the different approaches to measuring flow rates are:

  • Volumetric rate – The volumetric rate measures the space the material consumes and is seen as volume unit per unit of time, such as litres per minute.
  • Molar mass flow rate – Molar mass flow rate, commonly abbreviated to mass flow, measures the number of molecules per volume under specific conditions. The results are expressed as standardised volume units per unit of time under normalised conditions, such as standard litres per minute.
  • True mass flow – This measurement identifies the mass of the molecules in the flow, which is reported as units of mass per unit of time. (for example, grams per minute).

Measuring mass is an indirect process. The problem lies in the fact that momentum, weight, or thermal capacity need to be quantified. There are several ways that these measurements can be taken, depending on the fluid used. For example, a Coriolis vibrating channel can be used to measure the variation on the vibrational momentum caused by the mass flow of the gas or liquid. These devices are immune to variations in the fluid and unaffected by coarse and dirty flows. However, measurement integrity of this nature comes at a price, several times that of an Alicat instrument. Conventional Coriolis meters will provide mass, but no information as to the molecule count as they cannot identify the media in the line.

So what are the benefits of true mass flow?

There are numerous industries where true mass measurements are needed and can be beneficial. For instance, measuring mass per unit of time helps those operating in pharmaceutical production or with bioreactors, to make more accurate, simplified total mass calculations.

Delivering speed and flexibility

For operators that want to reap the benefits of measuring true mass but still have access to standard mass and volumetric flow, the solution is Alicat Scientific products. 247able, the e-commerce division of ABLE Instruments & Controls, is now able to offer UK companies an opportunity to buy the world’s fastest mass flow meters and controllers online using our simple-to-use product configurator.

Typically measuring true mass is associated with expense and the need for extra equipment. In fact, it can run into the thousands of pounds for a single instrument. However, Alicat Scientific’s technology means that customers can select engineering units, essentially accessing the functionality of multi-purpose measurement and control devices, at a very reasonable cost.

Using updated firmware, the Alicat Scientific products are able to measure the true mass of fluids in units that suit your application. This can be for a range of gases, including argon, carbon dioxide, hydrogen, nitrogen, oxygen, and propane, or any custom mix you build from the fluids on the instruments gas select list.

Where the Alicat products really stand out is their ability to accommodate a variety of different fluids. Alternatives generally provide true mass data for a single, pre-determined fluid, based on factory pre-programming. While this can meet some demands, the inability to adjust to viscosity changes compromises the traceability of such devices.

In contrast, Alicat M-Series mass flow meters, portable MB-Series mass flow meters and MC-Series mass flow controllers are designed with flexibility in mind. Customers using Alicat can effectively re-calibrate the instrument to a new gas via viscosity look-up tables. This is a unique feature which enables users to change gas types in the field without sacrificing the accuracy of their true mass flow measurements.

Alicat’s latest firmware allows for true mass measurement (click to enlarge)
Mass Flow Features

Picking the right mass flow meters for your needs

While not every business and engineer requires information on true mass, flexibility and versatility will often still be much sought after qualities when selecting a mass flow meter. This is where the Alicat Scientific products come into their own.

With just a few clicks of a button, users can easily and simply change between units and take advantage of the volumetric, standard volume, built in pressure control capabilities, and true mass units as required. The ability to field reprogram the flow instrument is a capacity that many companies will welcome, saving them money without having to compromise on quality, accuracy, or speed.

247able are a UK distributor, stockist and service provider of the Alicat Scientific range, which is industry proven and has received exceptional end user reviews. If you want to learn more about how Alicat products can be applied to your situation, we’re able to help.

Want to know more about Alicat Scientific Mass Flow Meters and Controllers? Contact us now at [email protected] or via phone on +44 (0)118 916 9420.

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