Gas Burner - Venturi Effect

In summary: Lower pressure and higher fluid velocity in the center of the flame encourages momentum away from the tube.
  • #1
34
0
Hi guys

I have a question regarding the working principle of gas burner. I was always have this question " How gas burner works using gas pressure lower -after been regulated- than atmospheric air ? "

Won't the the atmospheric air pressure prevent the gas from flowing?

Gas Burners

Both natural gas and propane burners work on the same principle called the "venturi effect". It says that as a gas or fluid passes through a pipe that narrows or widens, the velocity and pressure of the gas or fluid vary. As the pipe narrows, the gas flows more rapidly. What sounds like a surprise but holds true, is that when the fluid or gas flows faster through the narrow sections, the pressure actually decreases rather than increases. The venturi tube is a large diameter tube, gradually feeding into a smaller tube and then gradually becoming a larger tube

venturi.gif


burner.gif


On the photos below there are examples of different burners, all operating on a venturi principle. One of the main advantages of Venturi systems is operation without electricity

burner-10inch_sm.jpg


orifice.jpg


The most important part of the burner is the orifice plug with the hole in it. This is the point where the gas escapes from the hose or a pipe and enters the mixing bell of the burner. Orifice plugs are replaceable and screwed into the orifice spud. Nearly all atmospheric (venturi) burners have a gas orifice that is accurately fixed in the burner throat providing air intake. The hole in the orifice is very small to provide the correct gas flow and to provide sufficient velocity to ensure there is a suction (vacuum) available for the correct air inspiration.
The question again is " When the gas start to flow from the regulator with say 2 PSI, Why the existing atmospheric air pressure (14.6 PSI) just prevent the gas from flowing?

I hope that you get my question right
 
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  • #2
Surely it's gauge pressure, the 2psi is 2 psi above atmospheric.

EDIT: Very nice first post by the way.
 
  • #3
xxChrisxx said:
Surely it's gauge pressure, the 2psi is 2 psi above atmospheric.

EDIT: Very nice first post by the way.

Haha nice indeed, now I know how the air gets in! But it's nice because it's lifted directly from a website.
 
  • #4
Unrest said:
Haha nice indeed, now I know how the air gets in! But it's nice because it's lifted directly from a website.
I have not claimed that I have written this by myself, I have just wanted to ask question and I wanted to make things clear so as to understand me well and if this will add a new info for others -Knowing how their gas burner works- I will be pleased.
 
  • #5
xxChrisxx said:
Surely it's gauge pressure, the 2psi is 2 psi above atmospheric

I guess confusion came from that on some papers they use gauge pressure on sometime and absolute pressure on other times, they say:

The pressure after regulator is 2 PSI (gauge pressure), however when they want to talk about the atmospheric pressure they say it is 14.7 PSI
xxChrisxx said:
Very nice first post by the way

Thank you xxChrisxx but it is not my first post
 
  • #6
ameeno97 said:
I guess confusion came from that on some papers they use gauge pressure on sometime and absolute pressure on other times, they say:

The pressure after regulator is 2 PSI (gauge pressure), however when they want to talk about the atmospheric pressure they say it is 14.7 PSI

When talking about measurements it's common (and indeed common sense) to use gauge pressure, becuase that is what is easily measured.

I'd always assume that when a pressure is mentioned, it's gauge pressure. Unless it is obvious, or specifically highlighted, that it's absolute pressure.

ameeno97 said:
Thank you xxChrisxx but it is not my first post

I know, the post count under your name gives that away. It's just a pretty well presented OP, and has pretty pictures to boot.
 
  • #7
ameeno97 said:
I have not claimed that I have written this by myself, I have just wanted to ask question and I wanted to make things clear so as to understand me well and if this will add a new info for others -Knowing how their gas burner works- I will be pleased.

Yea I know. It's much easier to know what's going on!

But now my question is what stops the flame traveling back into the burner? I had assumed flames stay on the outside because there's no air inside. But it turns out there is.
 
  • #8
Lower pressure and higher fluid velocity in the center of the flame encourages momentum away from the tube. I think.
 

What is a gas burner?

A gas burner is a device used to combust a gaseous fuel, such as natural gas or propane, to produce heat for cooking, heating, or other purposes.

What is the Venturi effect?

The Venturi effect is a phenomenon where a fluid, such as gas or liquid, increases its speed as it passes through a constricted section of a pipe or tube. This decrease in pressure causes a suction effect, which can be used to draw in another fluid or gas.

How does the Venturi effect apply to gas burners?

In a gas burner, the Venturi effect is used to mix air and gas in the correct ratio before combustion. The gas is forced through a narrow opening, creating a low-pressure area and drawing in air through the larger opening. This mixture of gas and air then enters the combustion chamber, where it is ignited to produce heat.

What are the advantages of using the Venturi effect in a gas burner?

The use of the Venturi effect in gas burners allows for a more efficient and consistent combustion process. It also allows for better control of the air-to-fuel ratio, resulting in a cleaner and more complete burn with less waste. Additionally, the Venturi effect helps to reduce the risk of gas leaks and explosions.

Are there any safety concerns with gas burners that use the Venturi effect?

While the Venturi effect is generally considered safe and reliable, there are some potential safety concerns with gas burners. It is important to regularly check for any gas leaks and ensure that the burner is properly installed and maintained. It is also important to follow all safety precautions and instructions provided by the manufacturer.

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