Servo-motor control with BCS-460

Hello Guys,

I've built a HERMS system as shown on the picture below.

The system consists of:
- 3 kettles (Hot Liquor Tank, Mash Tun, Boil Kettle)
- High pressure burners
- BCS-460 controller

To control the burner I will attach a servo-motor on the gas valve. An exemple of the valve and the servo is shown on the pictures below.

This servo usually works with the following characteristics:
- Output period: 20 milliseconds
- Min pulse: 1 milliseconds (0 degree) - i.e. 5%
- Max pulse: 2 milliseconds (180 degrees) - i.e 10%

The problem is that the BCS unit works with a minimum granularity of the pulse of 0.1 seconds.

I am a Mechanical Engineer, so I don't understand much about electronic components. Anybody figured out how to control the servo using a BCS controller?
Any suggestions?

Thanks in advance.
Best regards,

My guess is you will need a separate PWM generator to control the servo. Then, use the BCS outputs to trigger it on/off.

Curiously though... Why not just use a valve on/off? Why do you need to regulate it? For boil control I assume? If so, you could just go two stage: full on and throttled (two valves and two outputs on the BCS).

-BD

BrunDog said:

My guess is you will need a separate PWM generator to control the servo. Then, use the BCS outputs to trigger it on/off.

Curiously though... Why not just use a valve on/off? Why do you need to regulate it? For boil control I assume? If so, you could just go two stage: full on and throttled (two valves and two outputs on the BCS).

-BD

Click to expand...

Thanks for the attention, bro!
I need regulate it to control the intensity of the flame, as the burner is high pressure and it's too powerful.

I have to agree with BrunDog here. You should be using the adjustment knob to set the flame level and then use a solenoid valve to simply turn it on and off. You will rarely use multiple flame levels on the burners. Both the HLT and BK will likely be set and forget once you decide on which level works best and the MLT would usually only need 2 levels. One for heating strike water (near max) and one that is throttled back for maintaining mash temp during recirculation. You're over complicating the solution here.

JonW said:

I have to agree with BrunDog here. You should be using the adjustment knob to set the flame level and then use a solenoid valve to simply turn it on and off. You will rarely use multiple flame levels on the burners. Both the HLT and BK will likely be set and forget once you decide on which level works best and the MLT would usually only need 2 levels. One for heating strike water (near max) and one that is throttled back for maintaining mash temp during recirculation. You're over complicating the solution here.

Click to expand...

The problem is that I made my brew stand using an industrial stove, as you can see on the picture. So, I can't modify it, like adding or replacing the valve.
In this way, my only solution is to attach a servo on the existing valve, or install an element and stop using the burner to control the temperature.

You're going to get a lot of heat wash hitting those servos mounted there. They'd probably die in a short period of time.

If it were me, I'd re-engineer the gas beam (pipe) feeding the valves. You could add an elbow to the valves that would point down, then add a solenoid valve to that, which is then connected to the gas beam.

Additionally, you'll never get the BCS to control the gas valves the way you are looking to do it. It's just not designed for that.

JonW said:

You're going to get a lot of heat wash hitting those servos mounted there. They'd probably die in a short period of time.

If it were me, I'd re-engineer the gas beam (pipe) feeding the valves. You could add an elbow to the valves that would point down, then add a solenoid valve to that, which is then connected to the gas beam.

Additionally, you'll never get the BCS to control the gas valves the way you are looking to do it. It's just not designed for that.

Click to expand...

JonW, thanks again for answering me!
I found out a way to change my stove, so it's gonna be possible to add a solenoid gas valve.
Can you suggest me a solenoid gas valve, remembering that my system is high pressure, i.e. it is directly connected to the LPG cylinder.
Thanks in advance.
Really appreciate your help.
Best regards.

diniz said:

JonW, thanks again for answering me!
I found out a way to change my stove, so it's gonna be possible to add a solenoid gas valve.
Can you suggest me a solenoid gas valve, remembering that my system is high pressure, i.e. it is directly connected to the LPG cylinder.
Thanks in advance.
Really appreciate your help.
Best regards.

Click to expand...

Good to hear you can change it. It will be MUCH easier for you to get automated.

I currently use solenoid valves from http://stores.ebay.com/valves4projects . I also just ordered more valves from them for my new build that is in process right now. Great valves, great price and great customer service.

FYI - even though your system is high pressure LPG, you have a regulator that attaches at the tank to regulate the pressure down.

JonW said:

Good to hear you can change it. It will be MUCH easier for you to get automated.

I currently use solenoid valves from http://stores.ebay.com/valves4projects . I also just ordered more valves from them for my new build that is in process right now. Great valves, great price and great customer service.

FYI - even though your system is high pressure LPG, you have a regulator that attaches at the tank to regulate the pressure down.

Click to expand...

It happens that my system is not regulated. It was designed for higher power burners, i.e. it is connected directly to the gas cylinder as the picture below:

In this way, I was thinking on using this valve, what do you think? http://www.ebay.com/itm/1-4-inch-11...Gas-Water-Air-ONE-YEAR-WARRANTY-/110904537199

Thanks once more for helping me.

Best regards.

EDIT: Thank you very much for sending the Ebay link. The valves are appropriate to high pressure system:
Pressure Range: 0 to 145 psi (normally a LPG cylinder handles 4 to 7 kgf/cm2)

I did something similar to what you're looking for with 2 valves in parallel that provide 3 levels of heating. I have a quick video showing it in the post below.

https://www.homebrewtalk.com/showthread.php?t=518609

I haven't had a chance to tie the full burner management into my PLC yet, but the proof of concept works. Spring came and the automation build is on hold until fall. Felt the need to cob together a solar powered fishfinder and led nav lights on my kayak.