Gas flow control: how to balance cost against specification

The many diverse applications for mass flow control often delimit a great many differing levels of specification, product features and service support capability. Original Equipment Manufacturers often describe their component requirements as being "fit for purpos", although many suppliers have often interpreted this as meaning "as cheap as possibl". Conversely, Research and Development scientists often look towards long term, with their flow control systems requiring the very highest specification with every possible feature and benefit, just in case they might be needed sometime in the future.

The traditional answer to serving these two extremes is to take the same basic measuring/control technique and add, or take away, layers of capability depending upon the cost requirement of the application. Similarly, the level of specification is varied into what essentially becomes a process of making the same instrument either a little bit better or a little bit worse.

Alicat Europe offers an alternative approach to this dilemma by manufacturing different instruments with different measurement and control techniques depending upon the specific needs of any given application.

OEM Mass Flow Controllers

OEM mass flow controllers are designed to be "more than fit for purpos" for stress-free integration into OEM products within an economical small footprint package. Based upon a high-accuracy MEMS sensor and still feature rich, they deliver 100ms speed-of-control response for eight pre-loaded gases with user accessible PID valve tuning, if required, to optimise in-situ speed of response and stability. Of special interest to equipment manufacturers is the detail that no warm-up is required as they are ready to measure almost instantaneously.

OEM Pressure Controller

A differing option for OEM flow control is the use of a fixed orifice together with an OEM Pressure Controller. This technique, the most cost-effective form of flow control, is also the most variable in terms of hardware as it can be specifically customized for optimised form, fit and function. PD valve tuning remains accessible for best speed and stability and dual valve configuration options are suitable for highly efficient dead-ended control (i.e. for non through-flow or enclosed volume applications).

Laminar Flow Element Mass Flow Controllers

These MFCs offer the highest specification available together with the most features and benefits within the one instrument. Four measurement instruments in one - mass flow, volumetric flow, pressure and temperature - are complemented by the user-selectable control mode function whereby with the push of a button the instrument can be set to control on either flow or pressure. The high specification continues with up to 130 gases pre-loaded, plus COMPOSERTM gas composition firmware for mixtures, all with no conversion factors; the accuracy statement remains true for each gas species or gas mix. The instruments offer bi-directional flow measurement and control on industry beating flow rates as low as 0.0025mln/min all backed up by the Alicat Lifetime Warranty. A suitable product would be the Alicat MC Series Mass Flow Controller.

Hand-Held battery Powered Flow Meters

These can be used to verify the proper operation of equipment; including other manufacturers flow meters and controllers, for installed equipment perform initial tuning and adjustments in the field or maintain proper equipment settings as part of a Quality System and/or Health and Safety Regime and, last but not least, search for leaks in a system utilising either the pressure or the flow reading. Also feature rich, these instruments offer user-selectable engineering units and standard temperature conditions, 5ms speed of response, stand-alone unit operation for use with or without a computer or PLC, all data visible on one screen (flow, pressure, temp) together with the ability to download data for logging or accountability purposes. A more than capable device would be the Alicat MB Series Portable Mass Flow Meter.

Conclusion

In conclusion, the capability to include differing measuring and control techniques across a wide suite of gas flow control instruments ensures that the optimum solution can be provided without compromise to specification, quality or service support capability. Go to www.pctflow.com to learn more.