It is not the differential of air flow between the rails and the hopper that we need to monitor but the differential ratio.
Example Cruising or slow driving at 3 inches at the rails and 1 inch at the hopper is fine . difference 2 inches
WOT and high rpms 45 inches at the rails and 15 inches at the hopper is correct ratio. difference 30 inches
If one wants to make it more simple for reading they could install a gauge at the rails that reads 0- 45 inches and one at the hopper that reads 0- 15 inches .
If these gauges rise and fall at the same rate all is well in the restriction area.
A person might get used to using it that way, but consider this:
12.5 & 5 would yield a ratio of 2.5 and a diff of 7.5, all acceptable
17 & 2 would yield a ratio of 8.5 and a diff of 15, not really good
25 & 10 would be a ratio of 2.5 and a diff of 15, but this is acceptable.
You see how the acceptable range would not be consistant with differential. I would recommend the differential on the hay filter for sure. But no one else would understand what you were seeing on the gasifier without at least one other gauge.
Hi Don
Just a thought, you could as you say do a pressure differintal between hopper and cooling rails, but at the manometer put two three way valves. So you can read the differential between the hopper and rails, or close the hopper and open that line to atmosphere to get an actual rail reeding, or the reverse close the cooling rails, and open to atmosphere, thus getting an actual hopper pressure.
My digital manometers came today and they are better than I expected. Nice big easy to see readouts that can be back lit at night. I never had to deal with inches of water readings before and was surprised how easy it was to suck 50 inches h2o. compared to hg.
I thought Iād try to summarize everyoneās 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 driverās 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, Iāve been working on an idea for the past few months (instead of making progress on my new gasifier, but itās 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.
Thanks Matt! Yes, each sensor (thermocouples, pressures, AFR) and calculated values (ratios) each have a low and high alarm value that can be set from the display. The buzzer will sound and the led associated with that sensor will turn red if the reading gets outside of the two alarm setpoints.
Billy,
Now thatās cool, I like gizmos.
What is the foot print of the display?
The only thing Iām not sure about is you only see one value at a time, right?
Wes,
The display is 4" wide and 3/4" tall. The display, leds and pushbuttons together are 2" tall.
Youāre right, only one value at a time is displayed. This is a definite drawback. The best ābandaidā Iāve come up with so far is using alarm setpoints on all of the readings. For example, if the hopper temperature rises while youāre watching some other value, the buzzer sounds and the red led associated with the hopper temperature lights up, alerting you itās time to refuel.
Iām not convinced this is the best workaround for monitoring multiple values with a single display, which is why Iām asking for feedback. I have some other displays that can show more than one value at a time, but the font is smaller and would be harder to watch while driving. It seems something has to be compromised if youāre trying to save dash spaceā¦
Thanks Carl! Right now, the display stays on whichever āchannelā you last selected, but scrolling values is a great idea. If each value was displayed for a few seconds, the cycle would repeat in less than a minute. What if the display jumped to whichever value was in an alarm state? What if more than one value is in alarm state?
Thanks Bill! If we can come up with something that the majority of folks here are happy with, Iāll definitely build more!
I think with values set for each and an alarm for some selected. This may work well with stationary units as well.A jack external for a light and another for a speaker for stationary units such as Patrickās?
Howdy Billy,
I like the āone stop shoppingā idea of it.
I would like multiple displaysā¦ Sometimes it can get real busy in the cab and pushing a button to see where things are are going, means taking a hand/eyes off somewhere they might oughta be.
A constant scrolling would be a good compromiseā¦ Would be nice if ya could choose what was scrolling. I think most people would have different preferences.
I also like the switch to the alarming valueā¦ If two or more are reporting at once, then it could begin scrolling them until a button is pressed.
Good stuff!
Iād really like to see this developed.
HWWT
TerryL
