Alicat Scientific Technical FAQ

Technical FAQ

What is the difference between mass flow and volumetric flow?
How do I convert mass flow to volumetric flow?
What standard temperature and pressure (STP) do Alicat Scientific devices reference?
Will reversing the flow direction damage my Alicat Scientific meter or controller?
What is the maximum operating line pressure of my Alicat Scientific meter or controller?
Are straight runs of pipe required to operate my Alicat Scientific meter or controller?

What is the difference between mass flow and volumetric flow?

At room temperature and low pressures the volumetric and mass flow rate will be nearly identical, however, these rates can vary drastically with changes in temperature and/or pressure because the temperature and pressure of the gas directly affects the volume. For example, assume a volumetric flow reading was used to fill balloons with 250 mL of helium, but the incoming line ran near a furnace that cycled on and off, intermittently heating the incoming helium. Because the volumetric meter simply measures the volume of gas flow, all of the balloons would initially be the same size. However, if all the balloons are placed in a room and allowed to come to an equilibrium temperature, they would generally all come out to be different sizes. If, on the other hand, a mass flow reading were used to fill the balloons with 250 standard mL of helium, the resulting balloons would initially be different sizes, but when allowed to come to an equilibrium temperature, they would all turn out to be the same size.

How do I convert mass flow to volumetric flow?

Please see our Theory of Operations page for information on converting mass flow to volumetric flow.

What standard temperature and pressure (STP) do Alicat Scientific devices reference?

All Alicat Scientific devices reference 25ºC and 14.696 PSIA (101.32kPa) unless ordered otherwise. Please refer to the calibration sheet included with your device to confirm the reference point.

Will reversing the flow direction damage my Alicat Scientific meter or controller?

No, the meter’s operation is uni-directional, reversing the flow direction will inflict no damage as long as the maximum specified limits are not exceeded. Please note that controllers will not seal effectively against pressure / flow reversals.

What is the maximum operating line pressure of my Alicat Scientific meter or controller?

Maximum operating line pressure is 145 PSIG (1000 kPa). Note: Exceeding the maximum specified line pressure may cause permanent damage to the solid-state differential pressure transducer within the device.

Are straight runs of pipe required to operate my Alicat Scientific meter or controller?

Because the flow meters and controllers set up a laminar flow condition within the flow body, no straight runs of pipe are required upstream or downstream of the meter.

WHAT'S NEW

We've moved!

Alicat Scientific moved to its new facility on June 11th 2009.
Our new address is:
7641 N. Business Park Drive
Tucson, AZ 85743
Please update your address books.

New communication protocols!
Alicat flow and pressure instruments can now be ordered with RS-485 or PROFIBUS.
Now quoting units with DeviceNet communications.