How to choose meters and controllers for pressure or flow

How to choose meters and controllers for pressure or flow

Alicat devices are available in thousands of possible configurations to ensure that the instrument you receive is the right fit for your application. In this first of a new series of blog posts centered on our available instrument options, we will be taking you through the main product categories in greater detail.

Alicat mass flow meter as part of the peregrine product line

Mass flow meter M-series from Alicat

Gas flow measurement and control

If you are looking for precision gas flow instrumentation, then we’ve got you covered. Our mass flow devices output the mass flow (standardized volumetric flow), volumetric flow (also referred to as “actual flow”), temperature and pressure. This means that you can sometimes replace multiple sensor components with a single Alicat instrument. Alicat uses a differential pressure-based flow measurement technology to calculate the volumetric flow rates, which are also converted to a mass flow rates using the temperature and pressure readings from inside the gas stream. These instruments can be configured as either a meter or a controller, which can control based on the mass flow, the volumetric flow or the pressure. All Alicat differential pressure-based mass flow instruments have a part number beginning with “M”.

Gas flow: Low pressure drop

Photo of MCW-Series low pressure drop mass flow controller

MCW-Series low pressure drop mass flow controller

Would pressure drop or a potential flow restriction due to a mass flow meter be a problem for your system? If so, you may be able to overcome this issue by using our Whisper series mass flow devices. Whisper series devices are configured with an over-sized flow body and laminar flow stack for a significantly lower pressure drop, and make use of a much more sensitive pressure sensor to maintain accuracy. The greater sensitivity to differential pressures results in a lower maximum pressure threshold for the Whisper series. Whisper series devices will have a “W” in the first block of characters in the Alicat part number (such as MW, MWB, MCW, MCRW, etc.)

Liquid flow measurement and control

Picture of Alicat LC-Series liquid flow controller

Alicat LC-series liquid flow controller

If you are working with liquids and need to measure or control the flow rates, our liquid devices may be right for you. Our liquid series instruments use the same principle of operation as our gas flow meters and controllers, and work best with pure filtered DI water. That said, we are sometimes able to customize them for metering or controlling different liquids (such as some alcohols) depending on the viscosity and materials compatibility (contact our application engineers at Alicat to learn more). All liquid devices have a part number beginning with “L”, and include bleed ports to remove trapped gas from the flow body (which can negatively impact the readings if left in the unit).

Pressure instrumentation

An Alicat pressure controller, 50 SCCM full scale, with a digital screen and standard valve, model PC-5PSIG-D, photographed by Alicat

Alicat PCD-Series gauge pressure controller

Though our mass flow series devices can both output and control on pressure, you may not be interested in the other variables (mass flow, volumetric flow, and temperature) or you may have pressure requirements that lie outside their range, accuracy or pressure reference (gauge, differential or absolute). If this is the case, our pressure devices may be the option you are looking for. We offer pressure controllers and gauges with full scales ranging from 2 inches of water column up to 1500 PSI. We can do a variety of configurations, and can build devices that output gauge pressure, absolute pressure, or differential pressure. All Alicat pressure devices have a part number beginning with “P”. Additionally, in the section of the part number containing the range of the sensor used, there will be an indication of whether the device is using a gauge, differential, or absolute pressure sensor (denoted by a “G”, “D”, or “A”, respectively).

Anti-corrosive options for flow or pressure Instruments

Alicat anticorrosive mass flow controller

Alicat MCS-Series mass flow controller for aggressive gases

Are you using a corrosive gas, or have potentially condensing liquids in your gas stream? If so, you should configure your Alicat device as an anti-corrosive “S” series unit. The anti-corrosive series Alicat devices are built with a 316L Stainless steel sensor and FFKM (Kalrez/Markez) that are more resistant to the aggressive gases and water condensation (though you should still dry a mass flow device out to prevent water droplets from impacting your flow measurement). Anti-corrosive Alicat devices have an “S” in the first block of characters in the part number (such as MS, MCS, MBS, MCRS, MCHS, PS, PCS, PCHS, PCRS, etc.).

Portable (rechargeable) meters for flow or pressure

A picture of an MB device

Portable MB-Series mass flow meter

Do you need to use your device where there is no access to power sources? All of our meters can be ordered as rechargeable battery powered portable devices with built-in lithium-ion batteries. In this configuration, they will include a micro USB cable and a wall plug for charging the battery. With a battery life of up to 18 hours on units with the monochrome LCD display (5-6 hours for the backlit color TFT display), you can measure the flow or pressure in the field away from local power supplies. Any portable device will have a “B” in the first block of characters in the part number (MB, MWB, MBS, PB, PBS, LB, etc.)

Alicat PCU portable calibration unit

Alicat PCU portable calibration unit

If you are looking for a very wide flow range in a single convenient case, then our Portable Calibration Unit (PCU) series may be a good fit. The PCU case contains three panel-mounted, battery-powered Alicat mass flow meters (standard or Whisper series) side by side with push-to-connect fittings. Each of the three meters can have a different range and comes with high-accuracy calibration and totalizer functionality. PCU part numbers begin with either “PCU” or “PCUW” (with Whisper meters) and include each of the three meter ranges (e.g. PCU-50SCCM-5SLPM-500SLPM-D).

That covers our main product categories. Stay tuned for the next installment, which will go over some of our controller-specific options in more depth. Would you like to know more? Explore our product pages and application notes to view more of what Alicat has to offer and how our devices can be implemented in common applications.

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