ACS Gas Training - Gas Pipe Sizing
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- Опубликовано: 24 ноя 2020
- How to size gas pipe work BS6891
ACS Gas Training. Gas pipe sizing. My name's Allen Hart, and today, I'm a Viva Training Academy, and I'm with Russ, the expert trainer. Russ is going to go through pipe sizing. We've got a few charts. This is a question that I get asked quite a lot. When I do my sizing, and I say, "We're only allowed one mb drop over the installation," on GAS pipe sizing, and people question that and say, "Well, manufacturer instructions say we can go down to 15 mb. People are misreading the installation instructions.
In this video today, Russ is going to go through pipe sizing. Some charts on there. There are also some charts here with the different sizes for different pipes. Russ is going to go through all these. Also, when you've got elbows and you've got Ts, how they affect your pipe sizing. This is going to be a very, very detailed video. It's going to go through the pipe sizing from start to finish really. If you do have any questions about pipe sizing, then obviously, please ask them in the comments below.
Yeah, I think that's it. So let's go over to Russ. This video is for gas safe registered and trainee gas engineers under supervision. Please comply with the current regulations of the time.
Thanks, Allen, for that. Today we're going to look a pipe sizing. Domestic pipe sizing, we'll call it on your SES up to the maximum 35 mil. All I want to do today is give you the principles of pipe sizing and show you some simple, straightforward exercises and practises. There are many, many different ways of pipe sizing. Different publications will show you different methods. I am slightly of the old-school, as you may imagine. I've done it one way for a long time, but there's a new method out there, which I'm going to show you today that I'm quite impressed with, and I've adopted myself. Different publications of this way show you different ways. This one we're using from our training manuals at VIVA training. We use logic, but you'll get the same information out of other publications, example, British Standards BS6891, that type of thing. They'll have the same systems in them. Hopefully by the end of this, and I am trying to keep this simple and break it down as much as I can, you'll understand where we're coming from, and why we pipe size, and of course, a simple method of how to pipe size.
Pipe sizing, as I hope you know by now, is a very vital part of gas pipe work. We need to supply the volume of gas required for the appliance, but we also need to maintain a tolerance within the pressure range. I'm going to give you round figures so you'll understand where I'm coming from, so we don't mess too much on that one. If we have 21 millibars coming out of our metre, on a low pressure system, we should have no more than one millibar drop across the system, therefore no less than 20 millibars going into the appliance.
We're going to do a couple of simple examples of pipe sizing. Remember what we're saying, we're looking to maintain pressure, but we're also looking to maintain that pressure with a volume of gas over a distance. Now the two examples I'm going to show you first are very simplistic, but will show you the difference in how to use the chart initially and how a different pipe size can completely change the pressure loss across that system.
We've got two different systems here. Very simple, very straightforward. In fact, it's all straightforward. You haven't even got any bends. It's a straight piece of pipe just to show you, initially, the example of that. First of all is 10 metres, 10 metres of pipe, up to 15 kilowatts of load. In other words, that boiler is going to use 15 kilowatts of gas per hour. That's the idea behind that. You can convert that to metres cubed, but in this particular case, you actually don't need to. You just work off the . It's one of those situations.
Same with this one. Shorter distance, but now a bigger appliance just to show what different it makes. What you must do on something like this is use a little bit of professional knowledge, if you like, or experience, which I know you don't have a lot at the moment if you're in the process, but it will come in time. You get a feel for what size pipe you need to put in. Now, remember, ideally ... Not ideally, exactly. If you've got 21 millibar coming out of there, you must have no more than one millibar pressure drop across the system. So you should have no less than 20 millibar to the inlet to the appliance, and still supplying sufficient gas to provide 15 kilowatts. 
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Russ you're a very good teacher, pls do more videos please
Been 5 years since my last Gas Core, doing it a few weeks time, Picked this up straight away. Brilliant 👍
Thanks Russ, very clear and helpful presentation and also lots of laymans tip which always help to simplify things.
It could not be more detailed...well done and thanks Allen
Helped me out a lot with this. Spent hours learning this but your method made it simple 👍
Glad it helped!
Thank you very much, finally you made it clear to me step by step.
Very well explain, a pleasure to learn from his knowledge
Great Video Allen thanks for your effort.
Great lecture, clear and concise 👍
Glad it was helpful!
This really helped make sense of all the charts etc in the training manuals. Thanks! 😊
You're very welcome!
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Explained really well thanks
Thank you for everything sir
Excellent video. Thanks alot
Very helpful. Thank you. 👍
This was really helpful, thank you.
Glad it was helpful!
Brilliant as usual
Thank You
Really good videos gave me a lot of confidence for my ACS which is in 3 days 😀
Mines is tomorrow, let me know how you get on
Great explanation thanks ; )
Once again brilliant video Russ and Allen.
Few questions I would like to ask:
1. When there is 2 or more appliances connected to gas meter, does each appliance have a limit of 1mb or is it both appliances have a limit of 1mb pressure drop?
2. If at a customers home and they want to upgrade, we should check if pipe sizing is sufficient enough for to allow no more than 1mb of pressure drop?
Very helpful
Glad you think so!
Great video. Im currently piping my home for propane but hope to one day have NG access. I understand that natural gas pressures are much lower than propane. If I size my pipe based on natural gas, would I be able to use propane appliances?
Great video, i am trying to use the viper gas book which shows it in a different way of working out sizing. Using the Viper book it came out all sections can be in 22mm. Would this work ? Thanks
Hi just a quick one, when calculating the Tee equivalent length from B-D in the last example for appliance 2 would you not use the largest connection size of 28mm (A to B) to give you an equivalent length of 2.3m not 1.8? or is that incorrect
what about the pressure drop for the pipe that piping from the ground to the 3rd floor did we talk the head as losses like liquids
I have a situation where I need some advice, my fire pit is 240k btu and 60 ft away from gas meter . My plumber installed 1/2” pipe all the way and fire pit is not getting sufficient gas due to smaller gas pipe size and recommend size is 1” for 60ft long . My patio is already built so it’s not possible to replace the pipe all the way and only option is to replace 50’ pipe with 1”and keep rest of the 10’ as 1/2” . Is it going to work provide enough gas for fire pit?
Hello great video - what was your source of chart at 10mins 59 seconds, where do i get that chart? thanks
Good video, you showed us the chart for pipe diameter, but would have been useful if you'd shown us the chart with the allowances for elbow and Tees also.
Great video Allen. As my house is currently undergoing a major refurbishment, a new gas boiler will be installed soon. I've been doing some calculations using the video from Russ here. The boiler will be located about 11 metres from the gas meter, so it seems to me that 6 metres x 28mm dia then 5 metres x 22mm dia are required.
But yesterday I've been digging outside to repair the drains and also replace the water mains (lead), and while I was at it, I saw a yellow gas pipe (which comes from the street to the gas meter in my cellar). I've measured the outside diameter of the yellow pipe using a vernier caliper and it is only 20mm (funny size I know).
So, I'm not sure if it would be a good idea to use 28mm from the meter if the mains from the street is only 20mm.
Can you please enlighten me? I hope to hear from you soon.
Thanks. Cheers
Ian
I’m no expert, but I imagine it’s at a higher pressure on the mains, and it is then reduced once it goes through the regulator on the meter. 🤔
Very good and clear. Why is the permissable pressure drop 1mB? Is it a standard, or does it change on different systems?
1 mbar is standard on all domestic natural gas systems. It's different for LPG, and on commercial gas systems of higher operating pressure. There will always be some pressure drop when gas flows through pipework. 1 mbar is achievable with reasonably-sized pipework.
Hi where do you find and download these charts thanks
Can you explain purge stacks and how there used
Purge stacks are used in commercial purging. They're not needed in domestic work.
Good
Great video thanks, however with legislation starting to go against new gas installations in terms of making it illegal to fit a gas boiler in a new build after 2025, do you think it's still worth training as a gas engineer at this point in time?
They are currently spending billions of pounds on the gas pipework. Anyone who believes gas is going is crazy in my opinion. Only time will tell though.
Where can I find the pipe size worksheet?
There is something i cant understand
i am not expert so i will appreciate your help
i would know how much the pressure going out from the meter should be and how much should be while it is into the appliances
I study that we install a stages of pressure regulator to regulate the value of it but no one ever said about that.
so sometimes the pressure drop can be neglected if the pressure value after it drops doesn't exceed the appliance pressure.
is that right?
Your question is somewhat difficult to understand, but I'll try: The working pressure coming out of the meter should be 21 mbar (plus or minus 2 mbar). This is governed by the regulator before the primary gas meter. The total working pressure loss along the pipes to each appliance should be 1 mbar (maximum). In the UK, natural gas appliances are designed to work optimally at 20 mbar (although they can usually work safely at lower pressures).
Can you do a video on why co levels might be really high.
I will chat with the Viva team and see what we can do. Thanks.
Hey Allen I’m 16 going into college to do plumbing first then I want to get into gas I know you have to do acs training any advice ?
Beware of training centres who want full up-front payment. Many are scams. Visit the place before you pay any money.
Can you explain purge volume on gas meters only, given that it not needed up to 70 kw on any pa perwork only on commercial paperwork
Cheers
Merry Christmas
For diaphragm meters, purge volume is 5 times the cyclic volume ("badge capacity") of the meter. As you say, this is only considered as a separate entity in commercial systems. In domestic systems, purge volume is either 0.010 m^3 / 0.355 ft^3 (for 28 mm pipes and U6/E6/G4 meter) or 1.5 times the installation volume of the system (35 mm pipes or U16/G10 meter).
Great video where can i dowload this exact chart from many thanks
It’s in the manuals. Thanks
@@AllenHart999 thanks allen
Can anyone help me out?
When working out the additional pressure loss by adding elbows, where did he get the 0.6m for the first diagram.
Also where did he get the 0.8m for the second diagram?
Is it just the length of the vertical pipe X by the two elbows?
I think he got that info from the chart for the different diameter of pipework 22mm and 28mm. He is using the paper for his calculations. It might be in BS 6891
@@mrproductivity3261 that’s the equivalent length of a 90 degree elbow for the 22mm and 28mm pipe respectively
How can I get this book sir?
Just to clarify at the end there B to C (0.15mb) + B to D (0.55mb) = 0.7mb total drop over both appliances.
Do you not need to add A to B (0.15mb) aswell which would give 0.85mb which is still under 1mb in this case?
Hi Lee, I would need to watch the video again to check but i am on my way out. I will look when i get chance. Thanks.
Gas flows along multiple, separate paths to each appliance. Pressure loss to each appliance is the total pressure loss along each path, not of all pipes on the system.
Good question, I'd like to know this too
@@Jehannum2000 So would that mean the each appliance has its own system which has a limit of 1mb of pressure drop for each appliance, you don't add the 2 different system's pressure loss to make sure its under 1mb??
@@mrproductivity3261 Yes. Let's say there are 2 appliances on a system (e.g. cooker, boiler). Say gas leaving the meter goes to a tee, losing 0.5 mbar in the process. The pipes from the tee to the boiler AND from the tee to the cooker can then lose 0.5 mbar each. Gas only follows one of these routes, so the total pressure loss to each appliance will be 1 mbar (not 1.5 mbar).
👍👍👍👍
👍👍
Extremely helpful video. I just wonder if the end calculation that totals 0.7mb by adding the pipe runs of b to c and b to d.
Should a to b have been added on also?
Seems unlikely he's made a mistake with this level of detail, but to myself a to b feels like a lot has been missed. For my own build this would be 8 meters lost so I'd really like to know.
Thank You
He’s already done that In the allowance from A To B that has to convey the full 40kw.
The A to B loss was 0.15mb, and that has been allowed for in both app 1&2. He’s done it separately so if you look,
A to B 0.15 mb
B to C 0.55 mb
Total 0.7 mb
What size is the tee it does not make sense. Sorry
Assuming that you have 20mb working pressure AT GAS METER and then you have an Ideal Logic which according to the MI's can do full output with inlet working pressure as low as 14mb, what happens if your inlet working pressure is 14mb due to pipe being undersized then? what about this 6mb pressure drop?
also,same situation with baxi 624,according to their MI's,it needs at least 17mb inlet working pressure, what if you have 17mb inlet working pressure at boiler,what about this 3mb pressure drop? what happens in these situations?
thanks
You are allowed 1mb drop over the pipework for pipe sizing. The boilers will work down lower in extreme conditions, That doesn’t mean in normal working conditions. Thanks.
@@AllenHart999 Hi Allen, thanks for your reply,not too sure about what you mean,i might not have worded it properly..i understand its max 1mb pressure absorption. but let's take ideal logic as an example, 14mb minimum according to MIs, so if you have 20mb working pressure at meter and due to pipe being undersized,you only have 16mb at boiler meaning 4mb drop across installation pipework, what about this situation? obviously 4mb is more than the 1mb allowance,but MI says boiler can work with inlet pressure as low as 14mb. lets say its a new installation, is it ok or does it make it AR or ID? thanks
@@11982463 Hi Im curious to find out if you figured this out, I would assume it is undersized pipework and ID because the pressure drop is way below 1mb. Please can you let me know what you found out.
Thank You
@@mrproductivity3261 with my limited experience , what i have seen in real world is that everybody just leaves it as it is, with the situation of more than 1mb pressure drop,but above minimum MI’s requirement may it be 14mb or 17mb… it doesnt seem to be an issue. Some with more than 1mb pressure drop n will still gas rate just fine. i have heard that the undersized gas pipework for boiler may affect other gas appliances, for example, it may affect the supply to a gas hob when boilers on maximum burner.. but im not sure
15kw devide it by 10.76 to convert it into cubic mtr per hour. .
Thank god my trainers weren't so boring and poor at communicating the principles during my apprenticeship
It’s just a shame they didn’t teach you how to be nice ❤️
If only sizing electrical cables considering 3 phase, power factor, length and size as well as installation condition were so easy …
… still at least I now know the difference between a ‘gas engineer’ and a ‘professional engineer’ ….
I wouldn't bother learning plumbing or gas work. It's a shite trade and less work now as too many engineers fighting for work and hassle of the jobs. Uk governmentals fighting russia and the economy is screwed for lower classes, so less money re-circulating. It's going to get a lot worst as the plumbers merchants are saying as they have seen a significant drop in sales. Just saying.
Can i speak with you on email because realy i need some Technical help
I'm WELLING TO REPEAT THIS EXERCISE BY MYSELF PLEASE FORWARD THE copy of the same tables used to enable me to pass the self-quiz I decided to carry out
Regards
A.A.ASHOUR
Thank You