What is the minimum temperature for an ignition hazard to occur?
In the surface temperature must exceed the AIT by 200ºC, for there to be an ignition hazard. a hot surface, since it will be, by far, the most volatile substance to be found there. Nonetheless, gasoline
Can the silicon carbide tip of a hot surface igniter be handled?
Some service technicians may be surprised to learn that the silicon carbide element of a hot surface igniter (HSI) can be handled without damage. However, it is better and safer to handle the igniter by the ceramic holder. The myth that the silicon carbide tip cannot be handled because body oils cause contamination is untrue.
How does an igniter module work on a HSI system?
On a typical heating system with HSI, a call for heat (thermostat contacts closed) will send a 24-V signal to the igniter module. When energized, the module will power up the igniter. If the module is a prepurge model, it will delay 15 or 30 sec before the igniter is activated.
Why is gasoline the hardest to ignite by heat?
Higher volatility fuels are harder, not easier, to ignite from a hot surface. Since gasoline is the most volatile of the common automotive-use ignitable liquids, it turns out to be the one which is the hardest to ignite by a hot surface. Nonetheless, in some cases, temperatures can become high enough for gasoline to get ignited.
What is the temperature of hot surface ignition?
What temperature would a metal strip ignite?
How is ignition of flammable liquids known?
What is the potential for ignition?
What causes a fire on a machine?
What is the surface temperature of an aircraft fuel?
Which is harder to ignite: gasoline or ignitable liquid?
See 4 more
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How hot do hot surface igniters get?
2500 degrees FahrenheitHot Surface Ignition systems use an 'M' or fork-shaped silicon carbide or silicon nitride igniter piece instead of a traditional spark igniter to light your gas flames. Low-voltage, but high-current electricity is sent through the hot surface igniter piece, heating it up to a glowing 2500 degrees Fahrenheit.
How hot does a furnace ignitor get?
2500 degrees FahrenheitThe ignitor sits beside the gas burners, and when the thermostat communicates that it's time to distribute warm air, the hot surface ignitor can reach 2500 degrees Fahrenheit. The gas valve then opens, and gas is ignited by the burning ignitor. The ignitor will burn out over time.
How does an HSI work on a furnace?
When the thermostat calls for heat, the HSI receives an electrical current which heats its surface. The igniter glows red and then lights the burners in the gas furnace. Over time, the igniter is continually getting red hot and then cooling, creating stress on the element.
What should a hot surface ignitor read?
0:363:26How to test a Hot Surface Ignitor - YouTubeYouTubeStart of suggested clipEnd of suggested clipWe set our tester to ohms resistance. As seen here the ohms resistance should be anywhere from 30 toMoreWe set our tester to ohms resistance. As seen here the ohms resistance should be anywhere from 30 to 60 ohms depending on the manufacturer of the igniter. If when tested you see no reading on your
What would cause a gas furnace not to ignite?
Common types of natural gas issues include gas leaks, blocked gas lines, and malfunctioning gas valves. If the gas line is off, simply turn it back on. If the furnace won't ignite after doing this, call an HVAC professional to check for other potential problems.
Why a furnace will not ignite?
If your gas furnace initiates the start cycle but does not fire up, it's likely because of a faulty, damaged, or dirty ignitor/sensor. This is a very common furnace problem—you can try to clean the sensor and replace the ignitor.
Is a flame sensor and Ignitor the same thing?
It is a rod that sticks out where the flame comes out of the burner. The flame sensor is always on the opposite side of the ignitor. For example, if the ignitor is on the right side of the burners, then the flame sensor is on the left side.
How long does a hot surface ignitor last?
Don't worry—an ignitor that goes bad is common for most furnaces. Fortunately, you can replace the ignitor without replacing the whole Furnace. Most ignitors last about seven years.
How do you test a furnace ignitor?
1:062:01Furnace Not Igniting or Heating? Igniter Testing, Repair - YouTubeYouTubeStart of suggested clipEnd of suggested clipUsing a digital model again rotate the dial to the lowest setting for ohms of resistance orMoreUsing a digital model again rotate the dial to the lowest setting for ohms of resistance or resistance with tone if your meter has this option to test the igniter shut off the power to your furnace.
How many ohms should a HSI read?
A good silicon nitride hot surface ignitor will have a resistance of 30 to 75 ohms. Greater than 75 ohms indicates a failing or failed hot surface ignitor. If you get 0 or ∞ or no reading at all, it mean that the resistance is broken, so the igniter is broken and should be replaced.
What voltage is hot surface ignitor?
Universal 120-Volt Hot Surface Ignitor.
How many volts does a hot surface ignitor need?
When replacing a hot surface igniter, it is important to know the supply volts needed for the new igniter. Most hot surface ignitors work off of 120 volts. However, there are a few out there that work off of 240 volts. The Honeywell SmartValve Hot Surface Pilot Ignition uses 24 volts.
How do you know if furnace ignitor is bad?
Here are a few indications that you have a faulty ignitor.No Cold Air. ... The Furnace Won't Come On. ... The Furnace Suddenly Stops Blowing. ... Starts, Then Stops, Then Starts Again. ... Tripping the Breaker More Than Once. ... I Hear the Click, But Nothing Happens. ... Flame Sensor Problems. ... Short Circuit.More items...•
How do I test my furnace ignitor?
Here are a few steps to check your ignitor and determine if it needs to be replaced.Make Sure The Furnace As At Room Temperature. ... Turn Off The Furnace. ... Switch Off Circuit Breaker. ... Remove Furnace Service Panel. ... Look For Visible Damage. ... Remove Ignitor Wires From Socket. ... Test The Ignitor With A Multimeter.
What voltage is a furnace ignitor?
In the USA, your furnace's ignitor will be powered by 120 volts AC when it needs to turn on. You need a multimeter to test if your ignitor is getting power. First, open up your furnace so you can access the ignitor. The ignitor is located behind the burner assembly.
How many volts does a hot surface ignitor need?
When replacing a hot surface igniter, it is important to know the supply volts needed for the new igniter. Most hot surface ignitors work off of 120 volts. However, there are a few out there that work off of 240 volts. The Honeywell SmartValve Hot Surface Pilot Ignition uses 24 volts.
Problem: Hot Surfaceigniter Does Not Glow
If 24 V does not check at the transformer, also check other controls in the circuit from transformer to module or integrated control. Check for 120...
How to Perform A Resistance Test
If the RTR is not to specification for igniter Model 201, which is a 34-sec warm-up time igniter of 45 to 400 ohms, or Model 271, a 17-sec warm-up...
Igniter Glows but Main Burner Won’T Light
Check for a good earth ground from L1 to the furnace chassis, you should read 120 V; if not, check and/or repair ignition ground wire or ignition c...
Checking The Flame Signal
According to a “Norton Igniter Products Technical Bulletin,” “Sensing through flame rectification, be it direct (through the igniter) or remote (se...
Main Burner Shuts offbefore T-Stat Is Satisfied
Check for foreign matter on the igniter or sensor. Clean or replace. Check the main burner ground by checking continuity between ground and burner....
How much heat does it take for gasoline to ignite? - Quora
Answer (1 of 6): Heat does not have an impact on the ignition temperature. Heat would only cause a rise in the fluid temperature. The ignition temperature is about 500F. It has to be above the flash point which is -50F.
Comparison of hot surface and hot gas ignition temperatures ...
A model describing the ignition of hydrogen-oxygen-diluent mixtures in the vicinity of a hot surface has been developed. The model assumes that ignition occurs as a result of runaway chemical reactions occurring in the gas, owing to heat transfer from the hot surface to the cold gas.
Ignition of Gases, Vapors, and Liquids by Hot Surfaces
Gases, vapors, liquid sprays, aerosols and other forms of ignitable fluids dispersed into the atmosphere, under certain circumstances, may encounter a hot surface. When investigating a fire, it may be necessary to determine in such cases if the hot surface was a competent ignition source. The paper reviews the available experimental data and findings on this topic and gives appropriate advice ...
Ignition of gases and vapours by hot surfaces and particles - a review
@misc{etde_5172766, title = {Ignition of gases and vapours by hot surfaces and particles - a review} author = {Powell, F} abstractNote = {A review of experimental and theoretical work carried out (since 1816) on the ignition of gases and vapours by heating surfaces, including hot bodies, particles and rods is presented. It is shown that the case of ignition of gases and vapours by hot surfaces ...
Hot Surface Ignition of Flammable and Combustible Liquids
Due to the known hazard of ignition of flammable and combustible liquids by hot surfaces, recent studies have been conducted to better understand the influence of various effects such as orientation of the hot surface, its size, surface material, and the residence time of flammable vapors near the h
Hot Surface Ignition of Gasoline on Engine Materials
For vehicle fire investigations, the issue of gasoline hot surface ignition [HSI] on an engine component will arise. To address the concern usually two facts are required; the fluid's lowest hot surface ignition temperature for the vehicle conditions and the temperature of the component surface at t
How long does it take for a silicon carbide igniter to heat up?
Once the prepurge timing is up (if so equipped), the silicon carbide igniter heats up to a proper ignition temperature (above 1,800°F) in either 17 or 34 sec, 20 or 40 sec for some models (depending on the manufacturer of the module).
What causes a boiler igniter to be shortened?
4. Furnace or boiler short cycling, delayed ignition, or an overgassed condition also contribute to shortened igniter life.
How long does the igniter stay on?
The igniter will remain on for a specific amount of time (seconds) depending on the specific ignition module being used. This “on” time or trial for ignition time can vary, depending on the specific ignition module being used.
How to tell if a spark plug igniter is cracked?
Allow the igniter to cool and perform a resistance test. Addi-tional signs of a crack are an “open” igniter (show s no continuity when tested), or a buildup of white silica dust around the bright spot. Replace the igniter if you see these cracks.
What causes a drywall igniter to fail?
In some cases, condensate dripping on the igniter causes it to fail .
What to check if 24V is faulty?
If 24 V does not check at the transformer, also check other controls in the circuit from transformer to module or integrated control. Check for 120 V from L1 to neutral (L2); check for 120 V from “IGN” to “IGN” or, on some modules, from the HSI terminals. If you have 24 V or 120 V to the module or integrated control, and no 120 or 24 V out of the module or integrated control, the module or control is faulty. Check the amp draw of the igniter; amperage should not exceed 4.75 A.
How to check if an igniter is bad?
1. Do a visual check of the igniter for signs of damage or cracks. The sleeving over the wire should be examined for chafing, burned portions, or cuts in the wire. The connectors should be properly seated and free from oxidation and/or corrosion. Look for hot spots on the igniter. Observe the igniter during heat up. If a bright, white line across one of the igniter legs is detected, a crack may exist that could cause premature failure.
What is the temperature of hot surface ignition?
If the degree of enclosedness is not extreme, a standard recommendation is that the hot-surface ignition temperature is assumed to be 200ºC higher than the AIT.
What temperature would a metal strip ignite?
They found that a metal strip heated to 1000 – 1060ºC would ignite natural gas. A larger data collection
How is ignition of flammable liquids known?
Although ignition of flammable liquids by hot surfaces is well known in the automotive and aviation industries, little fundamental research has been conducted to understand this ignition mechanism and only limited data is available in the literature. In this paper, we present results from over 2,500 ignition tests using a simple, highly reproducible experimental set-up involving a horizontal flat plate, a single drop of liquid and a quiescent environment. Results from the 14 automotive and aviation fluids tested showed that ignition was probabilistic, that the probabilistic behavior occurs over a relatively broad temperature range and that the data can be treated statistically using logistic regression. This statistical approach offers the advantages of inference and diagnostic techniques which parallel those of linear regression, and provides a well-defined relationship between surface temperature and ignition probability.
What is the potential for ignition?
INTRODUCTION There is a potential for ignition if gases, vapors, liquid sprays, aerosols and other forms of ignitable liquids become dispersed into the atmosphere and encounter a hot surface.
What causes a fire on a machine?
Industrial machinery fires are commonly caused by flammable operating fluids leaking onto hot machinery surfaces. This paper discusses doctoral research currently underway to identify the dominant fundamental mechanisms controlling the overall ignition process of combustible liquid stream-fed pools impinging on heated surfaces. Experiments are now underway to characterize these processes, via modeling and the use of dimensional analysis, to be able to predict the minimum surface ignition temperature for a given set of fluid and surface properties, more accurately define safe operating boundaries of equipment to mitigate fire events, and suggest optimal designs to widen the safe operating envelope. As a result of recent analyses, a surface modification technique has been proposed to use a pattern of micro-cavities, sized to prevent fluid seepage, on the exterior of the heated surface to reduce the heat transfer from surface to liquid (due to reduced direct contact), and inhibit the formation of superheated vapor films. This behavior could increase the temperatures necessary for ignition, permit-ting a wider range of safe operating conditions.
What is the surface temperature of an aircraft fuel?
Local air flow (0.8 to 50 meters per second) (2.4 to 152.4 ft/sec) effects were measured. aircraft fuels evaluated on titanium surfaces ignited (25 to 75 C) (77 to 167 F) lower (500 to 600 C) (932 to 1112 F) than values required to ignite the fuels on a heated stainless steel surface. Higher local surface air speeds necessitated higher surface temperatures for ignition of an applied fluid. The same trends were noted for hydraulic fluids sprayed on the heated surfaces.
Which is harder to ignite: gasoline or ignitable liquid?
Higher volatility fuels are harder, not easier, to ignite from a hot surface. Since gasoline is the most volatile of the common automotive-use. ignitable liquids, it turns out to be the one which is the hardest to ignite by a hot surface.
Why does my furnace have a silicone igniter?
Thankfully, furnace ignitors are typically very cheap, so it does not require much to replace it. There is a screw that contains the silicone igniter once you pull it out of your furnace .
Why does my gas igniter glow but no flame?
If your hot surface igniter glows but has no flame, this could be due to your gas valve failing to open, or the igniter being too weak. This means you need to test the wires to see if your igniter needs to be replaced. Sometimes, the issue is that it needs to be cleaned.
What to do if furnace isn't running?
If your furnace isn’t running, you can check out the igniter portion to see if it isn’t producing enough heat to light a flame. Your igniter may be glowing bright orange, but if it is on with the gas valve and not igniting, it is likely too weak.
Why does my furnace not have flames?
The last option that can cause a lack of flames comes down to how clean your furnace is. Anything can potentially snuff out a fire, and these can include things like dust and bold insects who wish to spend time here.
How to remove an old furnace igniter?
You will just need to remove the old igniter by loosening a bolt or screw on the front. You can plug it into an electrical component in the furnace, so be sure you are gentle while removing it. While you do this, be sure not to touch the igniter. The oil from your fingers can cause the igniter to burn out faster.
Do HVAC technicians have to go through tests?
However, HVAC installers and repair professionals have to go through a litany of tests to get where they are. Because of this, you should leave any more complicated issues for someone who has training on the matter.
Can you hear a gas valve?
If you listen to your HVAC system, you should be able to hear the hissing of your gas valve. In some cases, your HVAC system’s flame detector may not catch a flame in time. As a result, the gas valve will fail to open.
How long does it take for an ignition module to heat up?
In reading through the specifications for the operation of the ignition module again, the time specified for the igniter to heat up ranges between 17 and 21 seconds.
How many volts does an ignitor have?
The ignitor voltage is 120 volts on the money. I had my wife check the ignitor color and she said it was orange. I already reported the resistance of it to be 38.5 ohms.
What does it mean when a gas ignitor glows but no fire?
You have gas, and you have ignitor that glows - but no fire. It could be your ignitor is not getting hot enough. You describe it as yellow to orange. Should be more like brilliant pale yellow. But not to split hairs over descriptions - Ohms test the two wires going to the HSI, with it disconnected. Should be under 100. Often new ones I have found can be as low as 28 and up to about 50.
How long does it take for a gas valve to shut down?
A gas valve will indeed open with a bad HSI. And if there is no flame within about 4 seconds, the gas valve and HSI will shut down, and try agin until lockout.
How many VAC should a gas valve register?
The test I would suggest would be to measure the voltage being applied to the two contacts on the gas valve. That should register 24 VAC whenever the gas valve should be open. If you are failing to get voltage when the gas valve should be open, it's pointing to a defect in the ignition module unless some limit or pressure switch is opening.
What test will determine whether the relay that opens the gas valve to turn on the gas is burned out?
ecman's suggested test will determine whether the relay that opens the gas valve to turn on the gas is burned out. I doubt that's the case or the valve would never open.
Where is the flame sensor located on a gas stove?
The flame sensor is usually located on the opposite side of the burner compartment from the hot surface ignitor, and is commonly a thin round rod sticking up into the burner flames with a thin wire going back to the ignition module.
What is the temperature of hot surface ignition?
If the degree of enclosedness is not extreme, a standard recommendation is that the hot-surface ignition temperature is assumed to be 200ºC higher than the AIT.
What temperature would a metal strip ignite?
They found that a metal strip heated to 1000 – 1060ºC would ignite natural gas. A larger data collection
How is ignition of flammable liquids known?
Although ignition of flammable liquids by hot surfaces is well known in the automotive and aviation industries, little fundamental research has been conducted to understand this ignition mechanism and only limited data is available in the literature. In this paper, we present results from over 2,500 ignition tests using a simple, highly reproducible experimental set-up involving a horizontal flat plate, a single drop of liquid and a quiescent environment. Results from the 14 automotive and aviation fluids tested showed that ignition was probabilistic, that the probabilistic behavior occurs over a relatively broad temperature range and that the data can be treated statistically using logistic regression. This statistical approach offers the advantages of inference and diagnostic techniques which parallel those of linear regression, and provides a well-defined relationship between surface temperature and ignition probability.
What is the potential for ignition?
INTRODUCTION There is a potential for ignition if gases, vapors, liquid sprays, aerosols and other forms of ignitable liquids become dispersed into the atmosphere and encounter a hot surface.
What causes a fire on a machine?
Industrial machinery fires are commonly caused by flammable operating fluids leaking onto hot machinery surfaces. This paper discusses doctoral research currently underway to identify the dominant fundamental mechanisms controlling the overall ignition process of combustible liquid stream-fed pools impinging on heated surfaces. Experiments are now underway to characterize these processes, via modeling and the use of dimensional analysis, to be able to predict the minimum surface ignition temperature for a given set of fluid and surface properties, more accurately define safe operating boundaries of equipment to mitigate fire events, and suggest optimal designs to widen the safe operating envelope. As a result of recent analyses, a surface modification technique has been proposed to use a pattern of micro-cavities, sized to prevent fluid seepage, on the exterior of the heated surface to reduce the heat transfer from surface to liquid (due to reduced direct contact), and inhibit the formation of superheated vapor films. This behavior could increase the temperatures necessary for ignition, permit-ting a wider range of safe operating conditions.
What is the surface temperature of an aircraft fuel?
Local air flow (0.8 to 50 meters per second) (2.4 to 152.4 ft/sec) effects were measured. aircraft fuels evaluated on titanium surfaces ignited (25 to 75 C) (77 to 167 F) lower (500 to 600 C) (932 to 1112 F) than values required to ignite the fuels on a heated stainless steel surface. Higher local surface air speeds necessitated higher surface temperatures for ignition of an applied fluid. The same trends were noted for hydraulic fluids sprayed on the heated surfaces.
Which is harder to ignite: gasoline or ignitable liquid?
Higher volatility fuels are harder, not easier, to ignite from a hot surface. Since gasoline is the most volatile of the common automotive-use. ignitable liquids, it turns out to be the one which is the hardest to ignite by a hot surface.
