Home » Sierra Blog » Morgan Zealear, Engineer
Official Blog of Sierra--Let's Talk Flow!

How to Measure Air Flow Rate–Not As Easy As it Appears


Oct 04, 2013
Morgan Zealear, Engineer
Written By:
Morgan Zealear, Engineer

If we look at what is considered low flow measurement of air mass flow rate,  those applications ranging from 0 to 10 sccm up to 0 to 1000 slpm ranges, there is a right way and a wrong way to measure. It’s an inherent problem many of our customers face before they find the right […]

Read the Story

Under Pressure, Part 6: Size Matters with Flowmeters and Pressure Regulators


Oct 04, 2012
Morgan Zealear, Engineer
Written By:
Morgan Zealear, Engineer

In this final post on pressure regulation and flow meters, I’d like to present a case study. A customer was convinced that our unit intermittently lost control for given flow rates. It turns out that as they increased flow rate, the outlet pressure of the regulator (inlet to the mass flow controller) was drooping below […]

Read the Story

Under Pressure, Part 5: Flowmeters on the Ragged Edge of Pressure Drop


Oct 02, 2012
Morgan Zealear, Engineer
Written By:
Morgan Zealear, Engineer

Think about it. It’s pretty much impossible to make a controlled pressure drop without burning up some energy as heat. Therefore, the outlet pressure and flow rate cannot be linearly proportional at 1:1, but rather, must have some positive loss of X:1, where X is greater than 1. So, for a given regulator setpoint, the outlet pressure […]

Read the Story

Under Pressure, Part 4: More on Pressure Regulator Droop and Flowmeters


Sep 27, 2012
Morgan Zealear, Engineer
Written By:
Morgan Zealear, Engineer

If my previous post on droop, the least apparent pressure regulation issue, wasn’t enough of the low down for you, let me share some more about this common issue that arises with flowmeters. Droop is the difference between the outlet pressure at low inlet pressures and at high inlet pressures along the ‘operating range’ of the […]

Read the Story

Under Pressure, Part 3: How to Avoid ‘Droop’ (Hysteresis) with Flowmeters


Sep 25, 2012
Morgan Zealear, Engineer
Written By:
Morgan Zealear, Engineer

If you’ve been reading my series on pressure regulation, you know my goal is to help you achieve the best possible gas mass flow control with your flowmeter. Previously, I’ve discussed undersizing and seat-drop lock. Now I want to move onto something that can really get you down – “droop.” Regulators may exhibit hysteresis, also known as droop. Droop is […]

Read the Story

Under Pressure, Part 2: Don’t Run a Flowmeter Regulator into the Mud!


Sep 20, 2012
Morgan Zealear, Engineer
Written By:
Morgan Zealear, Engineer

Proper line regulation, be it supply pressure regulation, or back pressure regulation, is fundamentally key to a properly tuned flow system process. All instruments operate most accurately under steady-state conditions, so awareness of regulator behavior and proper tuning will save you time and money on avoiding waste during transient conditions. In my continuing tutorial on mass flow […]

Read the Story

Pressure Regulation Can Be a Sticky Wicket with Flow Meters


Sep 17, 2012
Morgan Zealear, Engineer
Written By:
Morgan Zealear, Engineer

In the world of mass flow control, it sometimes surprises me how often issues with mass flowmeters can be attributed to improper sizing of pressure regulators. But given all the intangibles with mass flow, I do get it. So, if you are building a flow system that requires precision gas mass flow control, this is the […]

Read the Story

Beautiful fluid dynamics images on an earthly scale!


Jun 29, 2011
Morgan Zealear, Engineer
Written By:
Morgan Zealear, Engineer

I am always struck by the often beautiful world of flow measurement. Even though we design and manufacture precision flow meters and controllers for nearly any gas, liquid or steam flow application, the images linked below explain why there are so many different measurement technology solutions (Vortex, Thermal, Ultrasonic, Magnetic, Coriolis…etc.) to handle the variety of fluid flow applications […]

Read the Story

Very Low Pressure Drop, High Flows: This Beast Has Wings!


May 05, 2011
Morgan Zealear, Engineer
Written By:
Morgan Zealear, Engineer

Meet the MFC we proudly call “Hammer-Trak”… What if you require very low pressure drop across your mass flow controller and need to control higher flows? Case in point: I had a customer asked me to design an MFC to handle medium-to-high flows (100-500 slpm Air), with at MOST 1.0 PSIG delta across the unit.  To solve this difficult probelm […]

Read the Story

Report Bug
Submit a Bug Report

Name

Email

Reproducibility (Did you try to reproduce the bug?)

Classification

Summarize the problem but be specific enough that it can be recreated.

Note: Page, browser, and OS are automatically saved