Operating Pressure at meter

[yorkieplumber]

Did a Gas Safety Check yesterday, and found the operating pressure at the meter to be sixteen mbar, i did this by connecting gauge to meter and opening three hotplate burners, so i informed the gas transporter that i could not achieve 19 to 23mbar at the regulator, they sent a engineer out but i left the job as i had other work to do, they promised they would get back to me with the outcome (they did"nt) so i phoned the customer and the transporter transco said it was fine, has anybody else had any problems like this? i think legally they dont have to supply 19-23 mbar has this can not always be achieved (old gas mains etc) will get back to them though and hopefully meet them on site to discuss further.

 

[Reg Man]

I think they have a legal obligation to provided at least 12mbars under the gas management regs. But you are correct in your testing and diagnosis for pressure. Just keep at them. Alot of appliances won't work and would fail a safety check without the proper pressure.

 

[stuartmac]

HI

What was the result of your tightness test when you first arrived at the premisis?

What was the result of the standing pressure test at the applicance?

What was the max / min operating pressure of the applicance you were testing?

What was the burner / working pressure of the appliance downstream of the applicance regulator?

All of these before you tried the pressure at the meter with burners on,

 

[yorkieplumber]

whats has a tightness test to do with operating pressure at meter? If you cant achieve 19-23mbar at meter you need to inform the gas transporter, which i did, but like i said earlier they will not guarantee you 21mbar.

 

[stuartmac]

If you carry out the tightness test first at the meter you will find out a, if there is let buy from the regulator, secondly the 1 min stabalisation test at 20mbr and 2 min test at 20 mbr will confirm that there is not a leak from the regulator ir upstream from the meter equally will confirm there is no leak from the meter to the appliances as per the gas safe requirements. the standing pressure test from the appliance will confirm the standing pressure of the pressure in the pipes. The burner or working pressure will confirm the pressure the appliance is working at if less than the pressures above check the pressure on the plate on the appliance it will tell you what the working pressure parameters are of the appliance some are less than 18mbr some work within a range of pressures. But if you have not doe the tightness test you can not confirm if the leak is upstream or down stream or in the appliance. Whilst the pressure they need to attain is 21 plus or minus 2 mbr appliances have to work at as little as 18. Some applicances as you will know you can adjust the pressure into it some you cant but the regulator on the appliance may reduce the pressure from 20 or so to that appliances particular pressure. Unless you have done the other checks you will not know what the issue is, if it leaks upstream of the meter regulator its Transco if its dow stream its you, however pressure drop from the meter if U6/G4 meter to existing appliances can be up to 8mbr ? All can be found in your corgi manual.

hope that helps

 

[stuartmac]

sorry forgot to say let by test first at 10mbr as part of the tightness test.

 

[stuartmac]

surley if you do not do a tightness test first you cant acertain where the leak is? if you do not test standing pressure at appliance the same applies ? if you know the first 2 and you get you working pressure too low then it is a fault on the appliance? the flame pattern would have been crap? the flame would have been trying to disapear back too source? incomplete combustion ? at risk ? fix or cap? if not and all looked ok what was the pressure at other appliances? surley test to see other pressures?

 

[yorkieplumber]

Stuartmac think you are getting mixed up if you read my post i have never mentioned a leak, the problem is the operating pressure at the meter, i cant even achieve 20mbar, the max i could get is 16mbar, that is why i have informed the gas transporter, as most appliances would fail a safety check, due to lack of pressure, you are getting mixed up carrying out a tightness test tells me nothing about operating pressure at the meter.

 

[Chelt_Plumber]

Transco will only change the regulator if the "standing pressure" is incorrect, if your standing pressure is lets say 24mbar (which is ok), then you turn the hobs on full flame to record the working pressure and its drops to 16mbar for example, you have pipe undersizing, its nothing to do with the meter

 

[yorkieplumber]

Chelt_Plumber i know its nothing to do with the pipe size to hob, why because hob is only 2 metres away from gas meter, i put the pipewok in last year, and the first metre is in 22mm it all checked fine last year. i have done the same checks this year as described in my first post and could only achieve 16mbar, the tests i have carried out is the way to check operating pressure at the meter, i have never suggested it has anything to do with the gas meter, look at my first post. i think its either the meter regulator (which we are not to adjust) or Transco can not deliver gas to meter at the required pressure, so when i fit a combi at the premises next week i know before i start i have pressure problems, so as far as i am concerned as a installer the problem lays with Transco.

 

[Reg Man]

Transco will only change the regulator if the "standing pressure" is incorrect, if your standing pressure is lets say 24mbar (which is ok), then you turn the hobs on full flame to record the working pressure and its drops to 16mbar for example, you have pipe undersizing, its nothing to do with the meter

I am sorry but this statement is not entirely correct. Standing pressure has little relevance to working pressure operation of the regulator.

Standing pressure is controlled by a lockup device built into the regulator. Its purpose is to prevent downstream pipes being charged with upstrem pressure. If it was not fitted or did not work we would end up with may be 75mbar pressure at your appliances. So therefore with the manometer connected to our meter test point and the ECV turned on but and appliances off we should see 24>25mbar and certainly no more than 30mbar standing pressure.

Working pressure can the be measured from the same test point by turning on at least three hotplate burners to allow sufficient flow of gas through the meter regulator to allow it to start operating. This should give you a dynamic working pressure reading of 21mbar +/- 2mbar. If not called the ESP in to adjust or replace.

So if we have confirmed 21mbar at the meter, we can then progess to the appliances and test the working pressure under full load (All appliances on) at the inlet connection to the appliance. We should be getting 20mbars dynamic working pressure, resulting in a 1mbar differential across out pipe run in accorrdance with BS6891.

 

[Chelt_Plumber]

Ah i see, it's weird how the didn't spot a problem when they checked it out, at least when you install the boiler you can get them out again and hear what excusses they have. To be honest ive never had a problem like this, my experiance with low working pressure has been caused by undersized pipe (which is ruled out) and once ive had debris in the pipe (a spring), god knows how that got there, but that caused a little drop, but not as much as yours.

Keep us posted with the outcome

 

[yorkieplumber]

Reg Man, could not put it better myself have had some strange replies to this post as you can see, thought i was losing it, do you agree with me that it is my understanding that the gas transporter will not gaurantee you 21mbar at the meter, ie old mains etc?

 

[villa_tom]

I had Transco out to a job the other day as I had 49mb standing pressure at the meter. He explained to me pretty much what RegMan has said, there or there abouts I wasn't listening properly as I was filling out paperwork. I think this post proves how difficult our job can be sometimes and how unclear some of the regs are and how different people interpret different things. Its been a good post to read though.

 

[yorkieplumber]

Glad post has been useful, we can all learn from each other i have been doing this work for 33 years, but still learn new things and ways of going about our work, when self employed its nice to have other peoples input as this is the way we can relate to problems/answers in our chosen field of work, or by the way villa_tom am going to James Milner sister wedding this year, my partner is a friend of his sister, does that nearly make me a celebrity? ha ha.

 

[villa_tom]

James Milner??? That bloke who went to win things at Man City and just sits warming the bench and is playing for a side who won't win the league in a million years and will struggle to get into the champions league at best! I'm not bitter or anything.

I guess it makes you a celeb. I'll look out for you in my missus magazines anytime soon. Just make sure your wearing a pair of snickers so I can pick you out.

 

[yorkieplumber]

Been told by of a lot of people he is a decent guy, am hoping i can have a chin wag with him, liked Aston Villa but why did they off load there best players they had the makings of a top team under Martin Oneal, but maybe there was more to it, maybe money.

 

[moogwai]

James Milner??? That bloke who went to win things at Man City and just sits warming the bench and is playing for a side who won't win the league in a million years and will struggle to get into the champions league at best! I'm not bitter or anything.

I guess it makes you a celeb. I'll look out for you in my missus magazines anytime soon. Just make sure your wearing a pair of snickers so I can pick you out.

James wwwwhhhhhoooooo!


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[stuartmac]

hi i know that but how do you know that the leak is with transco and not a broblem between the meter and appliances the tightness test would confirm this, or not

 

[yorkieplumber]

look at the post no one has mentioned a leak, tightness test was the first thing i did anyway, as i always do, please read my first post carefully.

 

[gas57]

contact transco they will replace meter regulator if faulty it may be gas pipe coming in to meter thats blocked they will check it out

 

[yorkieplumber]

gas57 done what you said, read my first post, what they are saying to me there is no problem, but i know there is, i am of the opinion they can not get 21mbar to the meter and trying to fob me off, if you look through my previous posts, i dont think transco can guarantee 21mbar at meter all the time, hi demand and old pipe mains i think they said sometime ago, legally i dont think they have to give you 21mbar, but am fitting a combi at the property next week so before i start fitting appliance i know i have got issuses, which in my opinion is down to Transco and not me as a installer.

 

[Reg Man]

If you carry out the tightness test first at the meter you will find out a, if there is let buy from the regulator, secondly the 1 min stabalisation test at 20mbr and 2 min test at 20 mbr will confirm that there is not a leak from the regulator ir upstream from the meter equally will confirm there is no leak from the meter to the appliances as per the gas safe requirements. the standing pressure test from the appliance will confirm the standing pressure of the pressure in the pipes. The burner or working pressure will confirm the pressure the appliance is working at if less than the pressures above check the pressure on the plate on the appliance it will tell you what the working pressure parameters are of the appliance some are less than 18mbr some work within a range of pressures. But if you have not doe the tightness test you can not confirm if the leak is upstream or down stream or in the appliance. Whilst the pressure they need to attain is 21 plus or minus 2 mbr appliances have to work at as little as 18. Some applicances as you will know you can adjust the pressure into it some you cant but the regulator on the appliance may reduce the pressure from 20 or so to that appliances particular pressure. Unless you have done the other checks you will not know what the issue is, if it leaks upstream of the meter regulator its Transco if its dow stream its you, however pressure drop from the meter if U6/G4 meter to existing appliances can be up to 8mbr ? All can be found in your corgi manual.

hope that helps

Sorry but I think some more revision in that CORGI book required. These comments have got little to do with gas working pressure. U6/G4 gas meter gas tightness test, maximum tolerance 4mbar. E6 gas meter 8mbar. Manufacturer instructions for appliance require 20mbar at inlet, thats why they are called G20 appliances.

 

[yorkieplumber]

Hi Reg Man, at last some one who knows what they are talking about, dont want to be funny, but some of these guys on this post need to check what they are saying, and how to go about checkig the the operating pressure of the meter regulator, if i cant get 21mbar ideally at this meter regulater then i am not going to get 20mbar at the appliance inlet, i know the pipework is correct size and has no blockages, so i said earlier the problem now lays with Transco, who i am hopefully going to meet on site next week. will let you know what my outcome is.

Steve.

 

[yorkieplumber]

Oh by the way stuartmac, the pipework and appliance are new, i fitted it all as per my earlier post, so no permissible drop allowed, as you rightly say all in the" corgi manual", which i think you need to revise a little.