How the production of steam is controlled on Pressurised Steam Generator ?

[sdancer75]

Hi,

How the production of steam is controlled on Pressurised Steam Generator that is not using a pressure switch but rather a control PCB board with MCU?

For example, in the case of Philips GC8220, as you can see at https://www.ifixit.com/Teardown/Philips+Pressurised+Steam+Generator+GC8220+Teardown/26948 there is no pressure switch to check the pressure inside the steam tank.

So, how the MCU in the control board knows the steam pressure level inside the steam tank?

[dmills]

You just heat the thing to a target temperature and make sure there is at least some liquid water in the generator, steam comes out at a pressure dependent on the generator temperature.

As you draw steam, more water boils, reducing the temperature and causing the heaters to add more heat, steam pressure is (for saturated steam) related to generator temperature by a simple curve (100 celcius = atmospheric pressure, 150 celcius = 4 bar, 200 celcius = roughly 14 bar), set the temperature and (as long as there is liquid water in the boiler) you know the pressure.

Regards, Dan.

[soldar]

So, how the MCU in the control board knows the steam pressure level inside the steam tank?

It doesn't. When you press the trigger it injects some water which instantly turns to steam and exits. There is no permanent pressurized steam boiler or anything like that. Just inject a few drops of water, turns to steam and it's gone. That's it.

[sdancer75]

So, how the MCU in the control board knows the steam pressure level inside the steam tank?

It doesn't. When you press the trigger it injects some water which instantly turns to steam and exits. There is no permanent pressurized steam boiler or anything like that. Just inject a few drops of water, turns to steam and it's gone. That's it.

I doubt about the trigger thing , since in this case it would trigger also the water pump which is not true and obviously there is no other way to inject water right ?

[sdancer75]

You just heat the thing to a target temperature and make sure there is at least some liquid water in the generator, steam comes out at a pressure dependent on the generator temperature.

As you draw steam, more water boils, reducing the temperature and causing the heaters to add more heat, steam pressure is (for saturated steam) related to generator temperature by a simple curve (100 celcius = atmospheric pressure, 150 celcius = 4 bar, 200 celcius = roughly 14 bar), set the temperature and (as long as there is liquid water in the boiler) you know the pressure.

Regards, Dan.

Thanks Dan, but what happens when there is no water in the boiler tank to heat (ie brand new device or after calc cleaning) but with full water tank.How is knowing that there is no water to heat and a water pump is needed to get some action ?

Another issue is the calc sensor. How this thing knows when a calc cleaning is needed ?

[soldar]

Maybe this will be useful https://www.semboutique.com/images/flexistore/sr24855x5515.pdf

[sdancer75]

Maybe this will be useful https://www.semboutique.com/images/flexistore/sr24855x5515.pdf

Thanks, i already have this.