Motorized valve Gas Burner

percy_nk

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Can any one suggest, I have Motorized valve Gas Burner (open and close) i want to control with PLC PID Control with RTD input and close and open relay, motor full open to close time is 30sec please suggest the logic to control
 
Burner Safety Stuff

Typically with these systems there is flame safety equipment that takes care of the position of the gas valve until the thing is lit and it sees the flame with a 'peeper'. Then and only then it gives a 'modulate' contact that lets you have control of the valve for temperature control. That's the way the Honeywell 7800 stuff that I'm familiar with works.

I'm trying to be polite and mean no disrespect - but your question indicates to me that you're new to the trade. You need your equipment design and sequence of operations reviewed by someone familiar with flame safety. If there's no flame safety equipment on the job walk away from it.
 
The Honeywell is the best they have been at a very long time contact you local distributer
Temp Setpoint and Actual Temp input to the PID control
the output from the PID to a 4-20ma output card
the 4-20ma output to the input of the Honeywell
Simple easy I have done it many time it works you will have to tune it but you will have to tune whatever you use
 
What is the controlled parameter? Is it

  • valve position (e.g. 0-100%);
  • valve velocity (e.g. ±X%/s);
  • valve direction (e.g. ±K%/s)
    • K = constant magnitude of valve velocity,
    • 3-state control i.e. opening closing, or stationary?
 
Usually 4-20ma for control of valve.
Flame safety is for ignition system (pilot), not control of modulating valve for burner gas, but modulating valve must be FM approved. (like Honeywell valve shown on previous posts)
There are other safeties required high and low gas pressure, main gas valve with failsafe close, and manual energize for gas once flame safety and other safeties are proven.
NFPA 86 is a good guide to requirements.
Is the valve controlling gas side or excess air side?
RTD for temperature sensor?? What is temp range of equipment?
 
Last edited:
This does not sound like a place for a roll-your-own solution. Many things can go wrong. If you don't have a flame sensor you run the risk of allowing a buildup of unburned gas, a potential explosion. If you don't also control the flow of combustion air you run the risk of a buildup of CO. Both of those scenarios can kill people. That's why people are recommending you purchase a burner controller from a reputable source.
 
PLC pid Motorized valve Gas Burner

drbitboy said:
What is the controlled parameter? Is it

  • valve position (e.g. 0-100%);
  • valve velocity (e.g. ±X%/s);
  • valve direction (e.g. ±K%/s)
    • K = constant magnitude of valve velocity,
    • 3-state control i.e. opening closing, or stationary?
Click to expand...

thanks,
valve position =0-100%
valve velocity=0-30sec. full close to open time
it is open and close
 
Steve Bailey said:
This does not sound like a place for a roll-your-own solution. Many things can go wrong. If you don't have a flame sensor you run the risk of allowing a buildup of unburned gas, a potential explosion. If you don't also control the flow of combustion air you run the risk of a buildup of CO. Both of those scenarios can kill people. That's why people are recommending you purchase a burner controller from a reputable source.
Click to expand...

And its a pain.... Fire Eye controller with the valve that Gary pointed out and a Honeywell UDC works great
 
percy_nk said:
thanks,
valve position =0-100%
valve velocity=0-30sec. full close to open time
it is open and close
Click to expand...


Sorry, I didn't ask the question clearly.


1. Is the controller going to control valve position e.g. is it sending a 4-20mA output signal from the controller to the valve, where 4mA will result in the valve being 0% (fully closed), and 20mA will result in the valve being 100% (fully open)? In this case, the controller will have an idea of the (intended) absolute position of the valve at all times.


OR


2. Is the controller going to control valve velocity e.g.

  • 12mA (half scale) will leave the valve at its current position i.e. valve velocity will be 0;
  • 4mA will tell the valve to move at maximum speed toward fully closed;
  • 8mA will tell the valve to move at half-speed toward fully closed;
  • 20mA will tell the valve to move at maximum speed toward fully open;
  • 16mA will tell the valve to move at half-speed toward fully open
In this case, the controller will not have an idea of the absolute position of the valve at any time.

​
OR


3. Is the controller going to control the valve direction e.g.

  • Sending a 0 to the OPEN discrete output, and a 0 to the CLOSE discrete output, will tell the valve to not move from where it is;
  • Sending a 1 to the OPEN discrete output, and a 0 to the CLOSE discrete output, will tell the valve to move at maximum speed toward fully open;
  • Sending a 1 to the CLOSE discrete output, and a 0 to the OPEN discrete output, will tell the valve to move at maximum speed toward fully closed.
In this case, the controller will not have an idea of the absolute position of the valve at any time.​
 
Last edited:

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