A flow meter is a manufactured device that measures (in volumetric or mass flow rates) the rate at which a liquid or gas moves through a pipe. There are different reasons why you’d want to be able to measure this, such as fine-tuning costs, emissions, and quality to name a few. Some liquids and gasses can be volatile or corrosive while others can be extremely expensive. Oil and gas are great examples of this. In cases of medicine and pharmaceuticals, all of the above apply, and more. For a direct example, flow meters measure the amount of paint applied to a pill. A central air system provides airflow to coaters. This measurement is strictly regulated to affect dyeing rate and thickness in coating. This should give you an idea of how commonly used flow meters are. This article will take a look at the two most commonly used flow meters in the pharmaceutical industry, as well as what the future of flow meters has in store.
Flow Meter Uses in Pharma
Speaking generally, there are many direct opportunities to use flow measurement devices in all steps of pharmaceutical manufacturing. These include and are not limited to:
- Raw material handling
- Production of an active pharmaceutical ingredient through chemical synthesis
- API extraction, fermentation, and purification
There are also indirect uses, like simplifying facility monitoring. Plants often sub-meter and independently separate departments to allocate costs. These meters compile data and can output to a central source for access, simplifying billing and controlling usage.
Pharmaceutical companies have many precise, important steps they must follow to create their products. This process works to their advantage by effectively creating more areas for control. There are a wide variety of options that help them to measure in the most efficient manner.
Turbine Flow Meters
Turbine flow meters are one of the most used flow meters in pharma-biotech. They use a bladed turbine rotor, usually held parallel to the pipe. You can think of them as drills. As fluid flows through them, it causes the rotor to spin, measuring the speed, which is directly related to the velocity of fluid. They must be made to rise above all the expectations and standards (think sanitation) and have many useful applications. They are also the most cost efficient solution, when selected for the right task.
Turbine flow meters can measure wide flow ranges with decent, responsive accuracy of about a quarter of a second. They are economic in pricing and easy to install and service. A big situational advantage is the opportunity to tailor the meters to specific features like temperature resistance, viscosity and density effects present in many pharmaceutical processes. Turbines have a wide range of process connections and extensions that are made for everyday, durable use and only result in a slight pressure drop.
These positives come with small sacrifices that could be deterring, circumstantially. Due to the nature of their construction, they are also limited:
- Accuracy can be affected by bubbles
- Can only be used with clean gasses and liquids, no corrosive fluids
- Requires a consistent velocity for accuracy, sensitive to changes in fluidity
- Require permanent back pressure to prevent buildup in crevices
- Commonly requires a strainer upstream to catch particulates
- Not practical for viscous liquids
Essentially, turbine flow meters are most effective when using consistent, clean, high-speed flows.
Coriolis Flow meters
Coriolis flow meters are a very popular pharmaceutical choice, as they fill the very demanding and specific regulations imposed on the pharmaceutical industry. Depending on your priorities, there are two types of tubes to opt for:
- Bent-Tube Flow meters are suggested for when precise, consistent and rangeable measurements are a priority.
- Straight-tube Flow meters are suggested where cross-material contamination is a concern, and sanitation is a focus. Cleaning works best in straight tubes, for obvious reasons.
Coriolis Flow meters are highly suggested for “Water for Injection” (WHO’s most effective medicine needed in a health system), RO, and DI water. This is because the purity cannot be compromised. Magnetic (or vortex) flow meters can expose the water to particulates and impurities. This is unacceptable.
Here are a few reasons why coriolis flow meters are so important to pharmaceutical manufacturers.
- 0.5%-100% Accuracy. Allows setpoint optimization. Few industries have such a demanding level of expectations and requirements. Precision measuring is the very core of the business. Inaccuracy equals faulty.
- Polished, straight pipe design to facilitate maintenance. No joints. This promotes a high level of cleanability. Cleanliness is an indicator of product quality. Almost all pipes and flow meters in Pharma are equipped with Clean-in-place (CIP) process. The value of such a system becomes apparent immediately. It cleans out and sterilizes the piping and vessels using a combination of DI water, and a caustic or solvent. It’s then processed through the piping for a set time and must be measured to meet the set safety standards.
- Metal only, all welded surface. The interior of the flow tubes (made of corrosion resistant metal alloys) is the only part of the flow meter that comes into contact with the process. No particulate breakdown from corrosion of exposed synthetic bits and pieces. No crevices within the device or materials for process chemicals to get stuck in.
The Future Of Flow meters
Prevalent in today’s manufacturing businesses and factories, it’s not difficult to see flow meters becoming more advanced. Technology and machines are on the forefront of science, enabling recent developments in security and control. Pre-calibrated, with supplied software, you can now plug in a USB and modify all of the operating parameters through your laptop, with an easy to use intuitive interface. These include HMI to match preferences to your plant, accessible through handhelds like tablets, or smartphones. This gives instant access to diagnostics, data, remedy based solutions to trends and process influences like corrosion, buildup, settling solids. Problems are beginning to take care of themselves at a faster rate. HMI’s can detect a quarter full pipe and create a log which can be accessed at any time. The increase in popularity of flow meters and technological advancement spawns a general improvement in the quality of life. Meeting regulations and requirements will become increasingly less challenging, and less time-consuming.