Been a boiler operator for 20+ years in state that requires a license and everyone I know blows down low water cutoff and water column every shift per Ohio code. Evaporation test done at least yearly, so in states that have licensed operators in my experience they are done regularly. And an inspector can look in internals of safeties and tell if you are blowing them down regularly.
Hey guys. Just a guy here who stumbled across your excellent channel. This was a particularly great video you all made. Thanks for doing this, I've learned a ton about steam and boilers from your videos.
Thank you guys. I do usually blow down the water column on all 13 boilers, but after watching this, I have a better idea as to why it needs to be done everyday.
I'm a serviceman, the gauge glass will tell you all about the boiler not just water level. You can see steam production on how the water dances in the glass, ooops that's a secret, if water not dance probably making wet steam, lol😆 Thanks for the video, you guys rock.
We had three 750 HP boilers Clever Brooks. Typically only two ran at a time unless it was real cold then maybe all three, summer only one. So if two where running I would fire up the not being used let it get to temp, and do a sight glass blown down and do the bottom down, repeat on the second boiler EVERYDAY. We would also rotate which two or one would run at any given time. So all three will be running at some point during the week.
Crown sheet failures are no joke. Gettysburg RR in 1995 emphasized the importance of safety. Crown sheets MUST NEVER be exposed to the heat. Always covered w water at ALL TIMES
Great video. Can you answer this question? Why do they need to add chemicals to boilers? And where are the chemicals added because isn’t essentially water flowing through continuously? Isn’t it just drinking water?
High water Alarms / cutoffs are optional so the boiler from the factory could potentially not have it. These devices will be very similar to the low water cutoff but typically mounted higher. Hopefully that helps. Thanks for watching!
Blow down the water column, gauge glass and low water cut out once per shift. Its no joke. The pressure will make your company happy, but your water level will keep them safe. Never sacrifice level for higher pressure or for production
ok how do you add water to the boiler and not have the injected water being added forced out due to the pressure inside the boiler. Is the water entering the boiler at higher pressure then internal pressure?
Depends on your local code. Boiler controls can be different depending on the local codes. Most BMS will require a manual reset on the local control panel before the boiler's burner can recycle back on if the aux LWCO trips the unit since its usually wired into the BMS's non recycling circuit. The level control pump on pump off micro switches on the Mcdonnell Miller with turn the feedwater pump on/off to maintain normal water level and the primary LWCO on a firetube will generally restart the burner when the level returned back to normal if the Mcdonnell Miller does not have a manual reset on primary LWCO switch and if it is wired into the BMS's recycling circuit.
If the low water cutoff is meant to be instant, how do you deal with large losses of load which cause the water to shrink rapidly and the reduction in firing from the trip causing the water level to continue shrinking (due to the reduction of steam bubbles) further exposing the tops of the water tubes? I understand that during constant loads running out of water can easily melt the tubes and the heat removed before this can do damage, but how do you deal with and adequately protect the boiler during load changes as the water inventory must increase (as the water shrinks) during a load reduction?
Thanks for the comment. In general it might seem like most water levels are around 50% of the sight glass but really is depends on the equipment and how it's being operated. It really just a case by case basis on where it should be. Hopefully that helps.
Generally, during operation the steam drum level is maintained from 40 to 50%. Because the steam will fluctuate the level in the drum. And it is advisable to keep the level 40 to 50%
Using the McDonall & Miller 750 series with the probe mounted in the top of the boiler, I find it very common that the 750 will not lock out the burner while there is water still visible in the sight glass while the boiler is operating (low pressure). I thought about cutting the probe shorter. But, if I shut the boiler down and blow down the boiler, the 750 will lock the burner out when there is still 1- 1.5" of water in the sight glass. What are your thoughts?
I would be very cautious before cutting the probe shorter unless it has been replaced and cut during installation. Perform some very detailed measurements before attempting to shorten the probe. It really sounds like there is some swelling going on when the boiler is firing. This is common on boilers with high furnace heat release rates or low sq/ft of heating surface to HP ratio. What happens is that while the boiler is firing you have a higher water level in the center of the boiler, where the highest heat transfer is taking place, than you do on the sides of the boiler. So even though the sight glass showed that the LWCO should have been dropping the boiler out the probe was still made due to the swelling. When the burner was turned off there was no swelling so the level had equalized. I have seen this and it is not uncommon. But I would do some additional test to make sure there is not a circuit issue. Is there some way that the 750 could be bypassed while the burner is energized? If you continue to drop the water level with the burner firing will it eventually drop the burner out? If not then you have a more serious issue that needs immediate attention. As always, make sure that you consult your boilers manual for detailed information on procedures or get with a local boiler service company to make sure the boiler is operating safely and efficiently. Thanks for watching and hopefully that helps!
@@wareboilers Yes. This does sound like swelling. The DOES eventually shut down the boiler. But when it does, the water level is out of the sight glass. It's still above the tubes so I think it's safe.
Cool video! I love the cutaway boiler. But Steven, water added to an overheated boiler can't "instantly turn into steam" for several reasons - mainly because a. the water is still under pressure, b. adding water takes time c. convective heat transfer from steel to water takes time d. steel doesn't hold much heat (only 0.12 BTU/lb/ºF) e. but water at 400ºF/250 psi still requires about 800 BTU/lb to turn into steam f. 400ºF water will hardly "wet" red-hot steel at all (Leidenfrost Effect), so with excessively high steel temperature (1200ºF) - amazingly - heat transfer from red-hot steel to water actually takes LONGER than usual at 400ºF. Weird, but true.🧐 g. In other words - adding hot water to red hot steel is exactly the same as adding red hot steel to hot water, it's not nearly as exciting as you think. In rough numbers - say, - ten 2" tubes ten feet long (~300 lbs of steel) - heated to 1200ºF - a dull red (800ºF over 400ºF boiling point) - only contains 21,600 BTU of "excess heat" - - theoretically, enough to turn ~27 lb of water (3.24 gallons) at 400ºF completely into 47 cu ft of steam at 250 psi. - say it took 2.5 minutes total to boil 27 lb completely, so only 13.5 lb *extra* steam/minute (810 lb/hour).🧐 Even if all the 27 lb of water boiled in 30 seconds, a 2" relief valve could handle more than double the extra steam the red hot metal could generate. And the hot tubes can't make steam any faster that you can add water, so if you trickle it in even slower, the total lb/min of excess steam cannot exceed the lb/min rate of water feed. But you need to add 2" water to the boiler to cover the tubes and quench them completely, which would require about 18 gal, or 150 lb - about 6X more water than the "excess heat" in the overheated tubes could boil (27 lb), so the *actual amount* of "excess steam" would be about 4.5 lb total. In other words, water added to an overheated boiler can't "instantly turn into steam" - for a lot of reasons. But it's still not a good idea to quench overheated tubes under pressure for stress reasons. They could shrink fast enough to pull loose, or tear right out of the sheet, which would be bad. So if we found the top row of tubes dry, and they are not leaking yet, I'd say shut off the fuel, stay calm, and don't do nothing except hold the water where it is until it cools down. If we found ALL the tubes were dry, I'd shut off the fuel and run like hell.😂 Please check my (crude) math, but I think it covers the basics.
I cannot agree with you conclusions. You mention the Leidenfrost Effect, and then say water can’t boil “instantly”. The Leidenfrost Effect is due to an insulating layer of...steam...that is generated so quickly that the water can’t fall through it to the surface. As soon as one bubble leaves the surface, water touches the hot surface and makes more...steam! And the fact that you cant instantly add 37 gallons of water exacerbates the situation. If you could instantly add a blanket of water to quench the hot spot, you could probably avoid an explosion. But what little water reaches the surface instantly turns to steam-and stays steam! If one gallon, or five gallons of water flashes to steam, what happens to the pressure? If the steel is red-hot, its because there’s fire behind it; you can’t just consider the latent heat in the steel. Good luck making the door! 😁
But how are u gonna test the secondary Low water cut off by opening the bottom blow down valve and watching the gauge glass to see if the burner shuts off before thr water in the glass dissapears IF the burner will or should shutoff before that point due to the primary low water cutoffs point of tripping the burner is before the secondary low watwr cut offs. U know what i mean? Do you temporarily jump out the primary low water cut off?
Why would anyone roll a tube standing behind the machine unless he want to get hurt. Your suppose to stand to the side with arms extended. Did this 4 29years in nyc.
I have the same question as DaGenius86. Also, when conducting the test, as the water level drops in the sight glass, isn't this water level matched to the water level in the drum (i.e. the drum level is lowering to the same point as the sight glass.)?
Ninguna caldera debería explotar sí tiene tapones fundación chimenea.y lo fundamental cuidar el agua condensación, qué el enemigo uno la espuma,y los instrumentos se confunden.tecnico vapor turbinas Laval. Operaciones.
Been a boiler operator for 20+ years in state that requires a license and everyone I know blows down low water cutoff and water column every shift per Ohio code. Evaporation test done at least yearly, so in states that have licensed operators in my experience they are done regularly. And an inspector can look in internals of safeties and tell if you are blowing them down regularly.
Good to hear from guys that are long term in the industry. Thanks for watching!
Hey guys. Just a guy here who stumbled across your excellent channel. This was a particularly great video you all made. Thanks for doing this, I've learned a ton about steam and boilers from your videos.
We really appreciate your comment! Glad that you enjoyed the video.
Thank you guys. I do usually blow down the water column on all 13 boilers, but after watching this, I have a better idea as to why it needs to be done everyday.
Thanks for putting out videos everyday I really enjoyed them ❤❤😊😊
Thanks for the videos, they are awesome
Thanks for your videos. Really nice for those learning about boilers.
Glad we could help. Thanks for watching!
I'm a serviceman, the gauge glass will tell you all about the boiler not just water level. You can see steam production on how the water dances in the glass, ooops that's a secret, if water not dance probably making wet steam, lol😆 Thanks for the video, you guys rock.
ex Navy ?
Amazing and important stuff... Thanks for this content...
Our pleasure! Thanks for watching.
Excellently explained!!
We had three 750 HP boilers Clever Brooks. Typically only two ran at a time unless it was real cold then maybe all three, summer only one. So if two where running I would fire up the not being used let it get to temp, and do a sight glass blown down and do the bottom down, repeat on the second boiler EVERYDAY. We would also rotate which two or one would run at any given time. So all three will be running at some point during the week.
Thanks so much for this. Learned something new.
Glad we could help!
Thanks for the video, very helpful.
Thanks for watching!
Thanks for the videos, Steven Taylor is one of my favorite trainers and I learn alot from all of you.
Thanks for your videos. We are learning a lot from your content. Greetings from Brasil.
Thank you
You're welcome
Very impressive.....
so basically the side glass it shows the water level of the control valve i think is the name of the valve where it has the sensors of low water.
Where can I get the drawing behind you at the end of the video?
Excellent explanations by the way
Crown sheet failures are no joke. Gettysburg RR in 1995 emphasized the importance of safety. Crown sheets MUST NEVER be exposed to the heat. Always covered w water at ALL TIMES
thanks from far-away ISRAEL. managed to learn a lot through your highly professional videos...
Thank you so much for the kind words and thanks for watching!
Great video. Can you answer this question?
Why do they need to add chemicals to boilers? And where are the chemicals added because isn’t essentially water flowing through continuously? Isn’t it just drinking water?
How does the high water pressure not blow out the sight glass?
What happen to low wtr cut off? Shuts down the fire in the blr.
So what device that prevent too much water in the boiler? The video show some sort of switch above the boiler but didn't mention it. Thanks
High water Alarms / cutoffs are optional so the boiler from the factory could potentially not have it. These devices will be very similar to the low water cutoff but typically mounted higher. Hopefully that helps. Thanks for watching!
Blow down the water column, gauge glass and low water cut out once per shift. Its no joke. The pressure will make your company happy, but your water level will keep them safe. Never sacrifice level for higher pressure or for production
ok how do you add water to the boiler and not have the injected water being added forced out due to the pressure inside the boiler. Is the water entering the boiler at higher pressure then internal pressure?
Yes because it has to overcome the steam pressure via feed pumps
Dude you rock✊🏿
Does the code require the second low water to lock out the burner controls ?
Depends on your local code. Boiler controls can be different depending on the local codes. Most BMS will require a manual reset on the local control panel before the boiler's burner can recycle back on if the aux LWCO trips the unit since its usually wired into the BMS's non recycling circuit. The level control pump on pump off micro switches on the Mcdonnell Miller with turn the feedwater pump on/off to maintain normal water level and the primary LWCO on a firetube will generally restart the burner when the level returned back to normal if the Mcdonnell Miller does not have a manual reset on primary LWCO switch and if it is wired into the BMS's recycling circuit.
This is why you make sure the low water fuel cutoff works
You are right! Doing a low water cut off test is an essential test to be done in the boiler room.. Thanks for watching!
Good
If the low water cutoff is meant to be instant, how do you deal with large losses of load which cause the water to shrink rapidly and the reduction in firing from the trip causing the water level to continue shrinking (due to the reduction of steam bubbles) further exposing the tops of the water tubes?
I understand that during constant loads running out of water can easily melt the tubes and the heat removed before this can do damage, but how do you deal with and adequately protect the boiler during load changes as the water inventory must increase (as the water shrinks) during a load reduction?
Are all sight glasses set up where water level should be around 50%
Thanks for the comment. In general it might seem like most water levels are around 50% of the sight glass but really is depends on the equipment and how it's being operated. It really just a case by case basis on where it should be. Hopefully that helps.
Generally, during operation the steam drum level is maintained from 40 to 50%. Because the steam will fluctuate the level in the drum. And it is advisable to keep the level 40 to 50%
I am looking boiler operator jobs in Italy please help me
Using the McDonall & Miller 750 series with the probe mounted in the top of the boiler, I find it very common that the 750 will not lock out the burner while there is water still visible in the sight glass while the boiler is operating (low pressure). I thought about cutting the probe shorter. But, if I shut the boiler down and blow down the boiler, the 750 will lock the burner out when there is still 1- 1.5" of water in the sight glass. What are your thoughts?
I would be very cautious before cutting the probe shorter unless it has been replaced and cut during installation. Perform some very detailed measurements before attempting to shorten the probe.
It really sounds like there is some swelling going on when the boiler is firing. This is common on boilers with high furnace heat release rates or low sq/ft of heating surface to HP ratio. What happens is that while the boiler is firing you have a higher water level in the center of the boiler, where the highest heat transfer is taking place, than you do on the sides of the boiler. So even though the sight glass showed that the LWCO should have been dropping the boiler out the probe was still made due to the swelling. When the burner was turned off there was no swelling so the level had equalized.
I have seen this and it is not uncommon. But I would do some additional test to make sure there is not a circuit issue. Is there some way that the 750 could be bypassed while the burner is energized? If you continue to drop the water level with the burner firing will it eventually drop the burner out? If not then you have a more serious issue that needs immediate attention. As always, make sure that you consult your boilers manual for detailed information on procedures or get with a local boiler service company to make sure the boiler is operating safely and efficiently. Thanks for watching and hopefully that helps!
@@wareboilers Yes. This does sound like swelling. The DOES eventually shut down the boiler. But when it does, the water level is out of the sight glass. It's still above the tubes so I think it's safe.
Cool video! I love the cutaway boiler. But Steven, water added to an overheated boiler can't "instantly turn into steam" for several reasons - mainly because
a. the water is still under pressure,
b. adding water takes time
c. convective heat transfer from steel to water takes time
d. steel doesn't hold much heat (only 0.12 BTU/lb/ºF)
e. but water at 400ºF/250 psi still requires about 800 BTU/lb to turn into steam
f. 400ºF water will hardly "wet" red-hot steel at all (Leidenfrost Effect), so with excessively high steel temperature (1200ºF) - amazingly - heat transfer from red-hot steel to water actually takes LONGER than usual at 400ºF. Weird, but true.🧐
g. In other words - adding hot water to red hot steel is exactly the same as adding red hot steel to hot water, it's not nearly as exciting as you think.
In rough numbers - say,
- ten 2" tubes ten feet long (~300 lbs of steel)
- heated to 1200ºF - a dull red (800ºF over 400ºF boiling point)
- only contains 21,600 BTU of "excess heat" -
- theoretically, enough to turn ~27 lb of water (3.24 gallons) at 400ºF completely into 47 cu ft of steam at 250 psi.
- say it took 2.5 minutes total to boil 27 lb completely, so only 13.5 lb *extra* steam/minute (810 lb/hour).🧐
Even if all the 27 lb of water boiled in 30 seconds, a 2" relief valve could handle more than double the extra steam the red hot metal could generate. And the hot tubes can't make steam any faster that you can add water, so if you trickle it in even slower, the total lb/min of excess steam cannot exceed the lb/min rate of water feed.
But you need to add 2" water to the boiler to cover the tubes and quench them completely, which would require about 18 gal, or 150 lb - about 6X more water than the "excess heat" in the overheated tubes could boil (27 lb), so the *actual amount* of "excess steam" would be about 4.5 lb total.
In other words, water added to an overheated boiler can't "instantly turn into steam" - for a lot of reasons. But it's still not a good idea to quench overheated tubes under pressure for stress reasons. They could shrink fast enough to pull loose, or tear right out of the sheet, which would be bad.
So if we found the top row of tubes dry, and they are not leaking yet, I'd say shut off the fuel, stay calm, and don't do nothing except hold the water where it is until it cools down.
If we found ALL the tubes were dry, I'd shut off the fuel and run like hell.😂
Please check my (crude) math, but I think it covers the basics.
I cannot agree with you conclusions. You mention the Leidenfrost Effect, and then say water can’t boil “instantly”. The Leidenfrost Effect is due to an insulating layer of...steam...that is generated so quickly that the water can’t fall through it to the surface. As soon as one bubble leaves the surface, water touches the hot surface and makes more...steam!
And the fact that you cant instantly add 37 gallons of water exacerbates the situation. If you could instantly add a blanket of water to quench the hot spot, you could probably avoid an explosion. But what little water reaches the surface instantly turns to steam-and stays steam! If one gallon, or five gallons of water flashes to steam, what happens to the pressure? If the steel is red-hot, its because there’s fire behind it; you can’t just consider the latent heat in the steel.
Good luck making the door! 😁
But how are u gonna test the secondary Low water cut off by opening the bottom blow down valve and watching the gauge glass to see if the burner shuts off before thr water in the glass dissapears IF the burner will or should shutoff before that point due to the primary low water cutoffs point of tripping the burner is before the secondary low watwr cut offs. U know what i mean? Do you temporarily jump out the primary low water cut off?
Why would anyone roll a tube standing behind the machine unless he want to get hurt. Your suppose to stand to the side with arms extended. Did this 4 29years in nyc.
I have the same question as DaGenius86. Also, when conducting the test, as the water level drops in the sight glass, isn't this water level matched to the water level in the drum (i.e. the drum level is lowering to the same point as the sight glass.)?
these are great videos.......but your animation on your steam gage logo is telling me its about to blow lol
Thanks for your comment!
Ninguna caldera debería explotar sí tiene tapones fundación chimenea.y lo fundamental cuidar el agua condensación, qué el enemigo uno la espuma,y los instrumentos se confunden.tecnico vapor turbinas Laval.
Operaciones.
It looked like the middle of the site glass was way below where the water level he said was supposed to be in the boiler?? Anybody else catch that?