Using IN-LINE Flow Filters to Protect Flow Instrumentation

• IN-LINE flow filters are design for Bronkhorst flow instrumentation and help protect the accuracy and performance of flow meters and controllers in addition to potentially extending its working life
• Filters for gas flow instrumentation can protect your investment from debris from contaminated gas lines, particles that exist in industrial gases, small amounts of oil from compressors, etc.
• While all flow instrumentation is susceptible to issues from contaminants in gas or liquid flows, sensors that rely on the bypass principle are especially prone to issues

It is often said, “buy cheap, buy twice.” This phrase is never more apparent than when purchasing new flow meters and controllers or evaluating ways to protect existing ones. But there are various accessories that you can add on to flow meters to improve their performance. IN-LINE flow filters help protect your investment against damage and can increase its working lifespan.

With mass flow instruments, the accessory of choice often is a communication cable, which allows communication between an instrument and a control system. This connection enables users to monitor or access critical feedback data that otherwise would be unavailable. However, there’s another accessory that is often overlooked. But it can be far more essential to improving the long term performance and lifetime cost of operating an instrument, in-line flow filters. This is especially true in industrial applications.

Using IN-LINE Flow Filters to Protect Mass Flow Meters

Simply installing this flow accessory to a new flow meter can protect against a multitude of issues like:

• Debris from contaminated gas lines
• Particles that exist in industrial gases
• Small amounts of oil from compressors

In-line filters are especially useful in applications where you have to deal with ‘dirty’ gases, or gases with particles. This is the case in both an industrial environment and in research applications.
While you may think that research applications will always use clean gases, tiny particles can also occur here. Not only the particles in gases can be a problem because there are contaminants in the pipes and tubes that can be harmful as well.

When using in-line filters, you can filter the gas before entering the flow meter. And this ensure that the gas at the inlet of the instrument is clean – without any particles. This way you avoid contamination which can lead to a number of avoidable costs. Such costs include downtime, service and repair, calibration costs, and engineering time to remove and reinstall the damaged instrument.

Inherent to its construction, a thermal mass flow meter or controller for gases is fairly sensitive to contamination. The thermal flow meters for gas can be divided into two sensor principles:

• Gas flow meters using the bypass principle
• Gas flow meters using the CTA principle (Constant Temperature Anemometry)

Bypass Principle for Gas Thermal Mass Flow Meters

If we look at flow meters using the ‘bypass’ principle, these instruments are more sensitive to contamination. Because in these instruments, only part of the gas stream flows through the sensor (bypass). And the rest of the gas will flow through the laminar flow element. This flow element, or flow splitter, contains small discs with high-precision flow channels. So, you can imagine that these channels may be clogged by contamination.

CTA Principle for Thermal Mass Flow Meters Gases

But instead of the bypass principle, instruments can be designed to use the CTA principle. Also called Constant Temperature Anemometry, inline principle, or direct-through principle, the CTA principle has no bypass sensor. Instead, it offers a ‘straight’ flow channel, so this construction is less sensitive to humidity and contamination.

IN-LINE Flow Filters Prevent Instrument Contamination

Preventing contamination of gas instrumentation is important for increasing the MTBF (Mean Time Between Failure). So it’s imperative to make sure that the gas or liquid entering the instrument is dry and clean. This is particularly crucial when using flow instruments with a bypass sensor. Depending on the fluid, you can select different types of flow filters.

Bronkhorst flow instrumentation is ideal for (ultra) low flows and therefore they have delicate and finely machined parts. This helps quantify low flow rates of gases with a high level of accuracy and repeatability.

Consider the potential damage from the different sources of contamination and the delicate nature of the internal working of a mass flow instrument. It should be a very straightforward decision to include a filter in your next purchase of a flow instrument!