Automatic boiler water level control system with phototransistor.

[Mechanicboy]

Hi folks who want to make own automatic boiler water level control system with phototransistor.

The control unit is registering the level of water using phototransistor + red led mounted on the water level glass tube. The servo is used to open / close the bypass valve between the boiler and waterpump operated by steam engine or open / close the steam valve to feed pump driven by steam pressure such like as Stuart feeding pump or Southworth feeding pump or as you created own feeding pump. Pump time can be adjusted as required by the phototransistor have registered lowest water level and pump on to it is higher than the phototransistor. The purpose is that it should not be often to pump water into the boiler. Light sensitivity is regulated depending on the size glass diameter and thickness as the receiving signal when the water is inside the water level glass tube.

The yellow led = low water/zero water level

The green led = normal water level

Both yellow and green led = water is pumping into the steam boiler

The yellow led is off and the green led is on = pumping time is ended when the water level is in normal position.

I did no want to drill hole in the boiler for water sensor since i has water level glass tube mounted on boiler. Hence i created the automatic boiler water level control system with phototransistor on glass tube.

Here is the diagram of the automatic boiler water level system with phototransistor.

 

[Entropy455]

This is a great idea.

FWIW - not often do you see a person with both metal-working and electronics knowledge.

Very cool.

 

[DJoksch]

On the farm as a small boy, if you could not lift the hay, you drove the tractors and made or mended broken parts in the machine shop. I’ve watch some well made videos using new state of the art CNC equipment and modern lathes with constant velocity features. I want to see a video series called “Holding a tolerance using old equipment from the farm”.

 

[dazz]

This is a great idea.

FWIW - not often do you see a person with both metal-working and electronics knowledge.

I resemble that remark. I have a Masters Degree in Electronics Engineering, two lathes, a Deckel clone milling machine and a double garage too full of tools to fit a car. If you look in the world of 3D printers (for example) you will find many others like me.

I like the idea of auto boiler control. It is a nice demonstration. I get that this is a model and nothing is critical but light sensors have multiple failure modes. Sight glasses fail too often. The usual approach is with a magnetic float and a Hall effect device. A copper boiler is transparent to static magnetism so the float could be inside the boiler with no additional penetrations required.

Also FYI, industrial control systems have indications like High High and Low Low, which indicate an abnormal condition that may require some other action. eg. shut off fuel supply.

 

[Mechanicboy]

I like the idea of auto boiler control. It is a nice demonstration. I get that this is a model and nothing is critical but light sensors have multiple failure modes. Sight glasses fail too often.

I have already installed in model steam tugboat and automatic boiler water level control system with phototransistor has worked just as well since 2016. I have not experienced crushing of glass tubes. Crushing of the level glass tube can occur if you tighten the nut too hard or do not check that the glass tube rotates freely before tightening the nuts with gasket with great care. Clean the glass tube if the phototransistor do not react on LED light due dirty inside. Use pure water in the boiler.

 

[DJoksch]

I had not thought much about the actual sensor yet, however it is easy enough to add a gas shut off condition. The liquid transfer ended up being one line of VHDL code. I found a source for stainless steel boiler probes, but I want to limit the number of holes. The Hall effect device is interesting.

 

[Toymaker]

Hi folks who want to make own automatic boiler water level control system with phototransistor.

First, congratulations on a successful project,...interesting choice to use photo sensors.
But I am curious,... why did you chose to use an optical sensor instead of a capacitive liquid level sensor?

 

[master53yoda]

I'm some what of a Lurker but my background before I retired was boiler controls and combustion. From experience always have a redundant mechanical back up on boiler system primary controls. I have seen electronic systems fail from either a shorted connection or a open connection depending on the electronics and leaving the system operating. Once we stop looking at everything with our eyes continuously we are trusting to chance " it isn't if they fail, its when they fail" because they will in the end.

Art b

 

[Toymaker]

I have seen electronic systems fail from either a shorted connection or a open connection depending on the electronics and leaving the system operating.

Art b

Your point of electronic sensors failing "and leaving the system operating" points to a system that has been poorly designed. Sensor failures on something as important as a water tank running empty should always set off an alarm and, if possible, shut down the entire boiler system automatically,...better to lose a few hours troubleshooting a faulty connection, shorted wiring, or bad sensor then to melt the boiler and burn up the feed pump because the system really did run out of water.

Automated systems should always be designed in such a way that if a sensor stops reporting, for any reason, that alone is considered a fault or failure, and appropriate actions should be taken automatically.

 

[master53yoda]

toymaker totally agreed, what I have experienced was temp controls that when disconnected sent a 32 degree reading, Myself, i like to see the programs such that if the reading is out of range it shuts down and alarms. Most boilers have manual reset high limits etc. that are redundant to the electronic controls. I have seen control system people like honeyxxxl install systems without out of range programing.

Art b

 

[dazz]

Hi
Industrial control systems aim to identify failure modes (short, open circuit, failed sensor, stuck sensor, power failure, etc etc) to then identify a fail-safe response. The aim being to ensure that a failure brings the equipment to a safe mode of operation (which may include turning it off).