This bought back memories...I did my Indentured Gas Apprenticeship in the 1960s when we still had "town gas". In those days the apprenticeship was from leaving school at just 15 to 21, almost 6 years. But, in those days we learned everything about gas, from how gas was made, how it was distributed throughout the district gas mains, how and why gas holders were built. etc, etc... It was a great apprenticeship, taught me well, and gave me a good living... oh, and it was quite common to get a clip round the ear off your fitter if you gave him some lip... Great times.
Another amazing video Derek, don't know why they've changed working pressure to operating pressure confusing our little brains. 😂😂, this was a brilliant video & well presented like always whether its in the classroom with you or watching you on videos you're always the top Tutor.. 👍👍😀😀
I think I’ve watched nearly all of your tutorials I now fully understand what you are saying keep up the good work and keep them coming Derek kind regards Tony gaunt🤗
Brilliant video derek. Revising for my Initial assessments. Thanks for giving us the understanding of not just carrying out standing & operating pressure but to understand why we have these figures in place i.e 21+-2. Trainee at tomkat gas training center. 🙂
...a great video Derek. Keep up the amazing videos you take the trouble and time to make. Just to give you some insight as to why they have changed 'working pressure' to now 'operating pressure. I know this video is I guess over two years since you made it, bvut I have just come across it now. That is'enough of the waffling, lets get right into it' as you say. 1. Working pressure: Well, working pressure is not a 'dare I say' a 'standard' . Unless ofcourse 'all' appliances were made to 'operate' at a specific given @ Rate of figure. Design, materials, size, etc will no doubt differ from for a start manufacturer to manufacturer as well as country to country. Operating pressure: So they rightly come up with the term 'operating pressure'.. This can now be used as a means of 'standard', covering all types of appliances as the manufacturers have stenciled the 'working/operating' pressure on the unit. 2. Standing pressure The 'standing pressure' is there as a form of supply and demand. Just to illustrate , lets bring in a water/shower pump. Say I connect up the water pump to the water Mains supply and Not an Overhead water Tank ! What will happen ? Depending on the regular 'usage', the pump will burn out , and that is within say 1 week. If you are lucky maybe 2 weeks. Why is that? It is because the 'standing' pressure is not meeting the 'operating' pressure of the pump. So the pump manufacturers as part of their design have used the 'standing' pressure as part of the formula to manufacture their different pumps. But the 'standing' pressure is Not the water Mains supply, but a water Tank. This will ensure there is enough water to meet the 'standing' pressure for that particular water pump. Hope my waffling helps. lol
Great video on tightness testing and pressures at the meter. Everything explained nicely and easy to understand. From now on I will try to refer to working pressure as operating pressure! Does anyone else take ages filling a u-gauge with water and trying to level it at zero and get soaked whilst doing it or is it just me 🤣. Thanks Derek 👍🏻 Asian Jon. Training.
Very good and appreciated Now if you can make some video on Regulations, ID,At Risk,responsibility of Landlord, Gas suppliers, and engineers, Thank you Derek Bless you 🙏
Thanks again Derek for sharing this helpful information with us it’s been very easy for me to understand that, also wondering where to getting a U_gauge like you’re using it in this video 🙏
Yes, you did say that if you have a drop you then test the carcass whcih is allowed a zero drop. This basically means the drop allowance is on an appliance that is fitted. (assuming no smell)
Great video as usual, could you please explain the following in your next video: Why is any MB drop allowed on appliances, it’s a gas leak! What is the correlation between type of meter and size of MB dropped allowed. Again great channel. 👍👍
Thanks again, great video. For operating pressure at meter, would you put all appliances on maximum at same time if you have more than one in property, say a boiler and cooker. Or just one appliance at a time? Thanks
I don't understand why they say add the two (water gauge) readings together and divide by 2. As long as you have zero'd the meter prior to any test the readings will be identical on either side - so you can just go off the positive side on the LHS. Just seems to be complicating matters. They should state you always zero the meter prior to any test ! I think its just making it confusing by adding the extra arithetic....
I’m just an interested viewer, ( ex industrial process operator) regarding the U tube manometer, when would their be an occasion when one side scale reading be a different reading than the other side ?
thanks. if you zero the u gauge then wouldn't the readings always be the same either side? what's the point in doing the calculation of bother sides ÷2 if both sides are the same?
Question, when you are performing the pressure test on the ECV, how do you know that it is the ECV that is at fault and not another part in the system?
Thanks. Why is it the case a drop is allowed with existing appliances connected? I may be completely stupid, but a drop is a drop no? Gas is escaping. Isn't that a problem? The wording the books and everyone uses seems to confuse things. Plenty of engineers seem to think if there is a drop on an existing system with old appliances and its within range then that's ok. Even the books don't explicitly make it clear that if you test with appliances on you have to ensure the the drop is on the appliance by isolating the appliance. The books split criteria for pipework into new and existing when really they should just say no drop is allowed and if you find one you have to ensure it's on the appliances.
@Derek, in Gas college they always told us the first thing you do before testing is using a volt stick on the meter on the anaconda I believe. no gas engineer ever does it though lol, do they have a point? is it uk reg? I think one in a million engineers got shocked or something one day
Yeah, it’s probably best practice but your video is to show us how do the tightness test and it is very informative, thanks for your videos, you’re doing great work.
So can i clarify pls. Working pressure/operating pressure is taken at the actual appliance and also the meter and allowed a drop of 1mb? Also what is the difference between a let by test and standing pressure? Surely in a letby your testing the section of pipe all the way from the ECV and throughout all the pipework up until the appliances in the house(so just the pipework in system with all appliances off).surely this area being tested is exactly the same in the letby and the standing pressure test?
let by test is testing the ECV to ensure it's working correctly when closed and isn't letting gas past it. Temperature stabilisation allows the gas pressure to stabilise before the tightness test. Tightness test is a test to ensure that there is no escape of gas from the installation downstream of the ECV and the installation is gas tight. Standing pressure test is to see what the standing pressure of the installation is and indicates whether or not the meter regulator is working. Working pressure, now renamed as Operating Pressure, is done both at the meter, and then at the appliance, to ensure that there is not more than 1mbar of pressure drop between the two when the appliance is running at full capacity (the exception being a cooker hob). working/ operating pressure is the same thing.
@@UndisputableFact surely standing pressure would/should be the same at the meter as at an appliance? If gas has nowhere to go because no leaks and no appliances are running then surely the pressure would be evenly distributed throughout pipework?
Im an apprentice but boss said that you can have good pressure at the boiler(call it 19mb) but still low gas rate when gas rating a boiler(seeing how much gas the boiler uses on max rate over a certain time). So gas pressure doesn't necessarily change if the gas rate does? I understand if you add up the amount of gas passed through the meter over a set time, whilst the boiler is on maximum, this will give you the gas rate? If thats correct does that mean if the gas rating came out lower than should be, that it could be inadequate gas reaching the appliance because of incorrect pipework sizing? Or it could be a boiler fault or fluing issue? But you could find this out by taking gas pressure at the boiler and if thats no lower than 18mb it would show that the boiler or fluing is at fault not the pipework?
@@Benji-gq9gx gas rates on boilers change with modulation and so does the inlet pressure and as long as you have less than a 1 mbr drop between working at the meter and inlet at the appliance and FGA is within tolerance and manufacturer instructions you could deem it safe
@@tomkatgastraining I'm still confused. 21 plus or minus 2 at the meter. So lowest allowed is 19 at meter. Then your allowed 1mb drop at the appliance. So this means the inlet pressure at boiler should never be lower than 18? However some boiler manufacturers say their boilers can be lower
@@Benji-gq9gx the lowest working pressure at the meter is 18.5 mbrs now if you suspect low incoming pressure. Even though the manufacturers say their boilers can work at lower pressures it will be at the gas valve p1 not at the inlet test point of the gas isolation valve
@@tomkatgastraining you mean the lower pressure will be at the gas valve inside the boiler not the isolation that often has a test point just underneath the boiler?
You have to have a minimum flow rate through the meter of 0.5m3 to a maximum of 3.5m3 for working at the meter but at the appliance it’s just that appliance running
@@lostinthoughtscalminsilenc8167 working pressure at the meter can be done with all appliances running as long as it doesn’t exceed the maximum flow rate or just one as long as it’s not less than the minimum
Why test the standing pressure and is there actually a requirement to do so? Please let me know if I’m wrong, but I was always under the impression the meter governor operated whilst gas was flowing through it-not whilst standing.
The standing pressure is a test to prove the regulator is working and how much gas you have. It’s one of those tests gas engineers don’t do because they think it’s not necessary. All the tests are there for engineers to determine if the installation is safe so if an engineer thinks there are no problems with the incoming supply then no need to do standing pressure.
@@tomkatgastraining thanks for your response. I thought “operating” (working) pressure is the test that proves the regulator is working correctly? Not the standing pressure. I’m sure the regulator only “regulates” when gas is flowing through it not whilst “standing”?
@@mattl9702 because you can have up to 75 mbrs on low pressure and up to 2 bar on medium pressure the standing pressure shows you if the regulator is regulating it down when the appliances are not running. It also shows when you have low incoming pressure.
@@tomkatgastraining So the regulator reduces pressure from ~75mbar to what pressure? Not trying to be a clever clogs, I’m curious. The reason I ask-I once got into a big debate with Transco years ago over the same subject. I was arguing the “standing pressure” seemed too high on a domestic property. To cut a long story short they disagreed and told me the working pressure was fine therefore all was ok. I’ve never tested the standing pressure since-that was roughly 20 years ago!
@@mattl9702 the regulator has 2 tests to see if it’s working which as you know are standing and working pressure. You can get a regulator working at 23 mbrs but if you leave it when the appliances are off it could rise to over 30 mbrs if the regulator is passing. As you know most gas engineers don’t care about standing and working pressure at the meter but as a trainer I have to show my trainees the correct procedures for testing safety devices and with a regulator being also classed as a safety device I have to show the correct testing methods.
Hi mate, when doing inlet at boiler and combustion. If I’m using a fga can I use them at the same time? Would I just isolate the gas put my probe in and attach my hose to inlet then put boiler to max and turn gas back on?
Not really sure what you are asking but inlet pressure is done with heating and hot water not high and low. High and low rates are for fga unless the boiler manufacturers say so
@@tomkatgastraining so you’re saying when doing inlet it does not need to be on high? My boss does them both at the same time? So I was just asking how I could do that? Would I just isolate gas put hose on inlet and probe in flue and put to full rate? As I use fga as a pressure guage
@@tomkatgastraining okay np, but when you do inlet you isolate gas first right? Is it bad if I can’t find where inlet is I don’t isolate the inlet so I can’t find where gas is coming out of then I isolate and put hose on?
It’s shouldn’t go below 19mbrs but Cadent engineers are told it can go as low as 15mbrs if the safe operation of the appliances are not affected in peak demand
@@tomkatgastraining Yes because there is an allowable 4mb drop across the meter installation at peak demand (BS 6400-1 6.2 for pressure absorption) which means that conceivably you might have something as low as 14mb inlet working pressure at the appliance, crazee! :D
@@MSKChess it dose say 15 Mbrs as minimum is 19 mbrs minus 4 is 15 working at the meter but also says this would only happen if pipe work is undersized for the appliance but like you say crazy 👍🏻
@@tomkatgastraining yeah in the notes it assumes one millibar drop for pipework, so four for the meter and one for the pipework giving 14 millibar at the appliance inlet. Maybe a Vokera I think can safely run as low as 14mb, but those big Worcester boilers require at least 18mb according to MI's. XD
I think they should just get rid of allowable drops on domestic as once you disconnected everything and see the hobs leaking 3mb who really re connects it and what customers ever say ok Hob leaks gas but it’s fine!
if you have proven that the leak is not on the pipework and the appliance is correctly sited and the room is adequately ventilated and there is no smell of gas then it should never reach a point where you have an immediately dangerous situation as there will never be an explosive mixture, some companies do have a zero tolerance approach to any gas leak regardless if its on an appliance. What gas engineer is going to feel good about leaving a 3mb drop on an appliance, hardly any, but British standards allow for it.
17:40 A gas flow rate of 3.5 m3/h should give you (3.5/0.095=36.8) 36.8 kW. A minimum gas flow rate of 0.5 m3/h should give you (0.5/0.095=5.3 ) 5.3 kW.
