Sunday, September 21, 2008


For personal reasons, I won't be bending metal or testing much over the next couple of months.   I will however have time to deskwork like posting to the blog.  I was wondering if anyone had any requests.  Design? Drawings?  Analyses?  Data? 

The video from this previous post was taken during testing of a bi-propellant engine I've been working on.   I've been testing various chamber lengths trying to get good combustion.  Here's a picture from a later test.  You can see the Swissflow flow meter bottom left.

Monday, September 8, 2008

Flow Meters

I've been using the SF800 from Swissflow lately to measure propane flow rate. It works well once you realize that the red wire is ground not positive supply. It uses BSP threads which are slightly inconvenient as well. The version I'm using has a fiber reinforced plastic housing and is rated for working pressures up to 230 psi. They have a metal bodied version rated up to 3600 psi that I plan to use with N2O.

Instead of using a steel rotor and a hall effect sensor, this meter has a plastic rotor with an IR emitter/collector pair. It outputs a nice square wave pulse with frequency proportional to flow rate. My DAQ board (from Measurement Computing) has a counter input which can be configured to measure frequency so interfacing to the existing DAQ software is quite simple.