I use one of these, Honeywell HIH-5031-001. I got it from CPC, about £10. It is a capacitive sensor with a built in circuit to convert to a voltage output. Its a three wire deice and it does require a low voltage input to drive it but its straight forward to use. Read the output with a DMM. Link to tech doc. http://sensing.honeywell.com/index.php?ci_id=49692
I use it to monitor the humidity of the airspace above the biodiesel when drying to determine the point at which the moisture content decreases no further. At this point the bio is clear.
Dave, slightly OT but did you see the guy on infopop posting about removing water with epsom salts?
That makes sense Bill. How are you going to know your bio is dry before seeding it with water, drying at @ 120degs?When you say you have now got a honeywell sensor, do you mean you have recently got it.
If you need confirmation of any water levels, just send me the samples and I will test with the S/B or KF (when I get some new reagents for it)
// Example testing sketch for various DHT humidity/temperature sensors
// Written by ladyada, public domain
#include "DHT.h"
#define DHTPIN 2 // what pin we're connected to
// Uncomment whatever type you're using!
//#define DHTTYPE DHT11 // DHT 11
#define DHTTYPE DHT22 // DHT 22 (AM2302)
//#define DHTTYPE DHT21 // DHT 21 (AM2301)
// Connect pin 1 (on the left) of the sensor to +5V
// NOTE: If using a board with 3.3V logic like an Arduino Due connect pin 1
// to 3.3V instead of 5V!
// Connect pin 2 of the sensor to whatever your DHTPIN is
// Connect pin 4 (on the right) of the sensor to GROUND
// Connect a 10K resistor from pin 2 (data) to pin 1 (power) of the sensor
// Initialize DHT sensor for normal 16mhz Arduino
DHT dht(DHTPIN, DHTTYPE);
// NOTE: For working with a faster chip, like an Arduino Due or Teensy, you
// might need to increase the threshold for cycle counts considered a 1 or 0.
// You can do this by passing a 3rd parameter for this threshold. It's a bit
// of fiddling to find the right value, but in general the faster the CPU the
// higher the value. The default for a 16mhz AVR is a value of 6. For an
// Arduino Due that runs at 84mhz a value of 30 works.
// Example to initialize DHT sensor for Arduino Due:
//DHT dht(DHTPIN, DHTTYPE, 30);
void setup() {
Serial.begin(9600);
Serial.println("DHTxx test!");
dht.begin();
}
void loop() {
// Wait a few seconds between measurements.
delay(2000);
// Reading temperature or humidity takes about 250 milliseconds!
// Sensor readings may also be up to 2 seconds 'old' (its a very slow sensor)
float h = dht.readHumidity();
// Read temperature as Celsius
float t = dht.readTemperature();
// Read temperature as Fahrenheit
float f = dht.readTemperature(true);
// Check if any reads failed and exit early (to try again).
if (isnan(h) || isnan(t) || isnan(f)) {
Serial.println("Failed to read from DHT sensor!");
return;
}
// Compute heat index
// Must send in temp in Fahrenheit!
float hi = dht.computeHeatIndex(f, h);
Serial.print("Humidity: ");
Serial.print(h);
Serial.print(" %\t");
Serial.print("Temperature: ");
Serial.print(t);
Serial.println(" *C ");
//Serial.print(f);
//Serial.print(" *F\t");
//Serial.print("Heat index: ");
//Serial.print(hi);
//Serial.println(" *F");
}
Can there be that much difference between inside and out side?
Can there be that much difference between inside and out side?
Yes there can. It is also temperature dependant.
Having got this far, I'm going to throw caution to the wind and risk my £1 sensor in bio before the others arrive!
Having thought about the above a little, if these sensors are that sensitive to methanol, then that could be quite a serious source of inaccuracy.
Having thought about the above a little, if these sensors are that sensitive to methanol, then that could be quite a serious source of inaccuracy.
Sounds like a serious source of checking your bio is meth free to me :)
But if the sensor can't distinguish between methanol and water, it's not a lot of use testing for either.
| Time | Duration in sample | %RH | Temp°C | Check Temp°C | Notes | |||
| Wet | 00:00:00 | ? | 35.6 | 21.4 | 22.0 | |||
| Dry | 00:00:00 | ? | 26.4 | 22.3 | 22.6 | |||
| Wet | 14:49:00 | ? | 40.1 | 18.0 | 18.6 | |||
| Dry | 14:58:00 | 00:09:00 | 29.5 | 19.2 | 19.5 | |||
| Wet | 15:17:00 | 00:19:00 | 41.9 | 17.2 | 17.7 | |||
| Dry | 15:36:00 | 00:19:00 | 32.1 | 17.7 | 18.2 | |||
| Wet | 16:13:00 | 00:37:00 | 43.5 | 16.4 | 17.0 | |||
| Dry | Lost the figures … Muppet! | |||||||
| Wet | 17:26:00 | ? | 47.8 | 15.4 | 16.0 | |||
| Dry | 18:16:00 | 00:50:00 | 36.9 | 14.8 | 15.4 | |||
| Wet | 21:19:00 | 03:03:00 | 49.7 | 15.6 | 16.1 | |||
| Dry | 12:02:00 | 14:43:00 | 54.6 | 15.9 | 16.5 | Next day | ||
| Wet | 17:07:00 | 05:05:00 | 58.1 | 15.9 | 16.6 | |||
| Dry | 12:23:00 | 19:30:00 | 63.5 | 15.7 | 16.3 | Next day | ||
| Wet | 12:50:00 | 00:27:00 | 63.5 | 16.2 | 16.9 | |||
| Ambient air | 19:48:00 | 06:58:00 | 45.9 | 18.7 | 0.0 |
Your max and min values are for wet 35 to 63 and dry from 26 to 63. That's overlap.
There is also an increase in readings as time progresses suggesting that there might be some sensor conditioning still going on as you were taking the measurements. I came across this with mine.
Try leaving the sensor in the dried sample for a couple of hours before taking any measurements and leave it in the dried bio between measurements but not necessarily powered up.
At the moment we are measuring samples at about dried+250ppm water and getting results which overlap. So are these sensors going to be sufficiently accurate to measure at the levels we need to find, which are ????.
Anyone any ideas about what should be in ????.
... The turbo dryer ...
When I finally get the meter I will test various samples pf versus sandy brae and graph them.
... I think the Arduino can be programmed to work as a capacitance meter, ...
Couple of points ...... The turbo dryer ...
Seen you mention this a couple of times. Is it a new fangled design not previously seen by humans before?
When I finally get the meter I will test various samples pf versus sandy brae and graph them.
I think that's probably the best starting point. If very dry bio has a propensity for atmospheric moisture, then samples should really be double checked so we know the actual content at the time of the test. Also we may be able to relate the readings you're getting from the sensor to ppm.
I think the Arduino can be programmed to work as a capacitance meter, I'll see what I can find out. If that's possible then I'd think the readings could be manipulated in the firmware to give a ppm reading.
Sorry Dave if I was rude to your work in doing the tests it wasn't intended. I was just commenting on the hardware build.
Cheers Julian and Dave. I am reading this thread with interest and while appreciating your work in the testing I was impressed by Julian's Sensor build which turns out to be a better design and build than the fully electronic ones previously tested. I think it's time I caught up on Arduino tech.
Oh God, Jim's going to program 747's to dive bomb selected members!
Just wondering how much water normal diesel contains. Has anyone tested diesel?
So the idea is to remove the moisture from the air to make the drying more effective
Have you not considered gold plating the chinese brass, an old colleague of mine would use his wedding ring to supply the plating surface.
It's amazing how little gold you need to plate a large area.
Alternatively can we pull Womble's gold tooth before we launch him ... shame to waste it.
Alternatively can we pull Womble's gold tooth before we launch him ... shame to waste it.
Oh ye', can I do it, can I pull all his teef out, please can I?
Alternatively can we pull Womble's gold tooth before we launch him ... shame to waste it.
Oh ye', can I do it, can I pull all his teef out, please can I?
Pull or punch ... whichever you prefer.
Could you assemble the plates with threaded brass or steel rod with washers to give
the correct spacing then silver solder remove the rod and then gold plate.
After gold plating reassemble with the nylon rod and spacers this way all
the metal surface will be plated and non will be shielded with the nylon.