I thought I’d try to summarize everyone’s thoughts on gasifier instrumentation, or at least my translation of this thread!
- Temperature and vacuum gauges are a simple and inexpensive solution to monitoring your gasifier but their placement is tricky to ensure they are easily visible from the driver’s seat, either directly or through the mirrors.
- The vacuum gauges can be mounted in the cab, but routing and protecting vacuum tubes from the gasifier to the cab can be cumbersome.
- Thermocouples are great, and relatively inexpensive, but the thermocouple extension wire to get the signal to the truck cab plus the temperature display costs as much if not more than the thermocouple. Weatherproof extension wire is preferred if not mandatory in wet climates, but is more expensive.
- Mounteing multiple gauges / displays in the cab chews up a lot of valuable dash space or requires building a custom center console to house them.
- An Air/Fuel Ratio (O2) gauge is another valuable tool to have, but chews up more dash or console space.
With all of this in mind, I’ve been working on an idea for the past few months (instead of making progress on my new gasifier, but it’s cold outside!) and would like to share my progress and get some feedback from all of you.
An 8-channel type-k thermocouple card, 3 pressure sensors (thanks GaryH for the great find!) and a microprocessor are housed in a weatherproof box mounted near the gasifier. Thermocouples are wired to a terminal strip in the box, resulting in short thermocouple wire runs. Vacuum sensor connections are 1/4" barbed fittings on the box.
An ethernet cable is ran from the box to an 8-digit display in the cab, allowing convenient access to all sensor readings. 4 other wires (+12V, ground, O2 sensor and parking light) are connected to the display. 8 pushbuttons on the display allow switching between sensor readings. 8 red/green dual-color leds keep tabs on what sensor is currently being displayed, as well as signifying alarm conditions.
Each sensor can be given an 8-digit custom name (HOPPER, GRATE, HAY FLTR, etc) that is displayed for a few seconds whenever a display button is pressed. Temperature units are selectable between C and F. Vacuum is currently only displayed in inches, but could be scaled to other units (mm Hg, kPa, or ?). Differential pressures can be displayed to monitor grate constipation, cooling rail plugging, or hay filter plugging. Vacuum ratios can also be displayed. Last but not least, Air:Fuel ratio can be displayed either as a voltage, a bar graph or a simple LEAN/RICH indication. There is a buzzer that sounds whenever a new alarm exists, and is silenced whenever any of the 8 pushbuttons are pressed.
Here’s a few pics of the box to be mounted near the gasifier and the display.