PCT

Premier Control Technologies

Flow, pressure, level and temperature solutions

Mass flow controllers

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Our range of gas mass flow controllers is manufactured by Alicat Scientific and distributed throughout the UK by PCT. We have a complete range of mass flow controllers which allows us to cover a large range of flow rates. From the smallest mass flow controller, which is capable of controlling flow rates from as little as 0.00025 SCCM (Standard Cubic Centimeters per Minute), up to our largest mass flow controller, which is capable of controlling up to 5000 SLPM (Standard Litres Per Minute).

We have mass flow controllers suitable for many different types of industry and application, from vacuum mass flow controllers to bi-directional. Our Whisper series is a personal favourite as it offers class-leading low-pressure drop.

The Benefits of Alicat Mass Flow Controllers


In addition to the many benefits high-lighted within the Mass Flow Meter section Alicat Mass Flow Controllers also offer the following benefits:

Customer Tuneable PID Control

Alicats MFC's are factory tuned to give "average" flow responses to set-point change to enable them to function well across a whole range of diverse applications. In addition, factory pre-set tuning is available when a customers' specific conditions are known, however, more important still is the ability for the customer to tune in situ when conditions were unknown or when they change. This in-process tuning allows the speed of response to be further increased over and above the general responses mentioned below.

30 – 100 ms Fast Control Response

Not only is the measurement of flow extremely fast but so are the control electronics and control valve are also fast to give typical flow rate response times of between 30 and 100 milliseconds.

Bi-Directional Mass Flow Control

Bi-directional mass flow controllers have two valves; one to control the flow in a forward direction, the second to control the flow in the backwards flow direction. The first valve is connected to a pressure source to provide the motive force to generate flow; the second valve can be connected to a vacuum source to then "pull" the flow through in the opposite direction.

Stand-alone Control Functionality Especially with the Integrated Potentiometer Option

By having the factory pre-set, or by selecting the local set-point option via the front screen buttons, it is possible to operate the device in stand-alone mode whereby the set-point can be increased or decreased at the push of a button. Other than the power cord, no other cables or electrical signals are required. This can be made even easier by selecting the integrated potentiometer fitted to the top of the electronics housing whereby the set-point can be varied by simply turning the pot.

Ramp Function

The ramp rate can be set serially or via the front panel and can be applied to the control of mass flow, volumetric flow or the pressure. The rate of ramp rangers from instant through to one week to get to full scale (at 0.1% rate resolution) all the way to three months to full scale (with 1% rate resolution). The ramp can be selectively applied to UP, DOWN or both with selectable response on zero setpoint to either ramp or instant off.

Valve Hold Function

A valve "hold" function can be applied that sets a constant control signal to the valve thereby holding it in the same position regardless of process change. This is useful for such situations as when the pressure needs to be changed and there is the risk of PID conflict within the flow path. The user can 1. set hold on the mass flow controller, 2. Adjust the process pressure via the Alicat pressure controller, 3. Turn off the hold function and resume normal variable control of the flow rate.

There are numerous other benefits to an Alicat Mass Flow Controller as follows:

  • Multiple alarms, separate from control, voltage source or open drain.
  • No straight run of pipes are required.
  • Alicat devices can control to the lowest set-point on the market, 0.0025 sccm.
  • Alicat devices are tough and survive bumps, dings and even being dropped – check out the video below.

Operating Principle of Alicats Mass Flow Controllers

Mass flow controllers continuously compare the output signal as derived from the flow meter section with the setpoint signal as generated locally, within control electronics or from a laptop or PC. Both signals are monitored by the comparator and any deviations between the two being translated into an adjustment signal to the control valve. Should the measured flow rate be less than that required by the set-point then the signal is increased to open the valve further. Conversely, if the measured flow is too great then the valve is slightly closed to restrict the flow rate. When controlling from zero flow to full scale this adjustment takes place within just a few tens of milliseconds, however, once in steady state any process fluctuation is compensated for almost instantaneously.

Alicat offer a vast range of different valve solutions that are engineered to solve many diverse applications. Small valves, large valves, two valves in parallel, two valves in cascade mode are all solutions that have been developed to meet the needs of the customer.

Applications

Applications for Alicat mass flow controllers are present throughout Research, Academia, Industry, Analytical and the Environmental Industries to name just a few. Some examples would be:

  • Gas mixture generation
  • Glass preform control
  • Analyzer plasma gas control
  • Analyzer calibration gas control
  • Bio-reactor feed gas control
  • Burner gas control
  • Sputtering process control
  • Coating technology gas control
  • Brewing process gas (N2, O2, CO2)
  • Nitriding gas control
  • Metals industry Argon lance gas control
  • Flame spraying
  • CVD process gas control
  • Surface treatment gas control
  • Fibre drawing gas control
  • Analyzer carrier gas control
  • Welding gas control
  • Fuel cell flow control
  • Modified atmosphere packaging gas control
  • Ice-cream and fondant aeration
  • Microbiology process control
  • Solar panel coating control
  • Micro-Reactor gas control
  • ALD ultra-fast flow control
  • Vacuum deposition gas control

Common Questions and Answers

My application is for burner flame control with low pressure fuel gas. Can an Alicat Mass Flow Controller help?

Yes. Whisper Series mass flow controllers are specifically designed for high flow burner applications at low inlet pressures (for example when used with town gas). Furthermore, with tunable PID the modulation of each gas supply can be matched to eliminate the potential for an over-rich flame at one extreme and "flame blow out" at the other.

I have used an MC-5SLPM-D/5M,5IN,GAS:O2 for many years and now wish to add a second supply but at 20 barG. Should I order the same part number?

Unfortunately not. The MC Series is rated to 10 barG, however the good news is that the Alicat MCQ-5SLPM-d/5M,5IN,GAS:O2 is rated to 22 barG.

My process feeds the gas into a vacuum chamber and I would like both ultra-low flow rate control as well as positive shut off. What would be the solution?

The MCV Series is specifically designed for vacuum systems, conforming to the NESSI Standard, and with its soft seat is ideal for very precise ultra-low control. In addition, the integrated pneumatic shut-off valve ensures positive shut-off. As the instrument fits to the industry size envelope and the electrical connections can be made to match any configuration, the MCV Vacuum Series mass flow controller is an ideal "drop in" replacement for any other manufacturers device without any difficulty.

We can see that Alicat instruments are feature rich and offer a lot but we do not require all of this within the analyzers we produce. Do uou offer something more simple and cost effective?

Yes. The Alicat BASIS instrument range is designed to be exactly that. Flow ranges span from 1 sccm to 20 SLPM across the range with up to eight gases being pre-loaded (Air, CO2, Ar, O2, N2, N2O, He and H2 - please ask about other gases). The MFC is instantly on – no need for warm up – and very fast in its control response (100 ms).