Smell of leak gas in my house

[Ztah]

Just need a quick advice if anyone can help. This afternoon I felt as if I smelt a gas so called national grid if they could help with gas leaks as cadent company recently did some gas works on our road. They sent the engineer out from cadent, he checked with some instrument all through the house. Wht he explained to me is that there is a pressure drop of o.5mb near meter. He also told me that there is about 40ppm reading on his instrument near hob. What he has told me that this is permissible drop but I am just concerned if that is ok otherwise he suggested that i should contact a gas safe engineer to get that sorted out if I am worried as its not their side of leak its somewhere between meter and hob or meter or boiler.
Please help
Thanks

 

[johnduffell]

well, if there's a drop on the carcass and you can smell gas then it needs sorting as there's no reason for that to happen. Yes it's legal to have a small drop but if you can smell it then there must be a leak. You can get the hob checked out at the same time if you have concerns.

 

[Ztah]

What does it mean when it shows 40 ppm on the device near hob ?

 

[Ztah]

Is it significant enough ? I mean is it dangerous

 

[johnduffell]

that means the hob is not burning the gas properly and should be checked and cleaned, could be many things but a proper gas person will be able to get to the bottom of it.
I don't know if it's specifically dangerous but it's a lot higher than it should be and without knowing why it could easily deteriorate further.

 

[bacon_sandwich]

40ppm is very small you did well to smell it. 0.5mBar drop is more concerning, assume this is a house. When he says its acceptable , well it is if you are using a water gauge but most engineers use digital pressure test equipment, 0.5mBar drop is outside acceptable oddly and could be what you are smelling.
Best get a gas engineer in to check all your joints and double check the tightness test. Hopefully it should not be hard to find.... but they can be like looking for a needle in a haystack. Good news is 0.5mBar is a good enough drop to find.
Hope this helps

 

[Ztah]

The earliest i can get the eng tomorrow.
Is it the dangerous drop?

 

[Ztah]

What could be the problem ? Maybe tiniest leak anywhere between pipe and hob?

 

[johnduffell]

Was the hob reading the carbon monoxide when it was running or the gas leak? If it's carbon monoxide then open a window when using it in the mean time.
Anyway, the emergency guy would have disconnected your gas if they considered it immediately dangerous so try not to worry too much. But if you can leave a window on the crack it would give you peace of mind until then.

 

[Ztah]

Thanks
That helps

 

[bacon_sandwich]

Carbon monoxide does not smell, hopefully the gas guy was measuring actual gas (unburnt) 40ppm is very small and no risk of explosion. At first opportunity get a Gas Safe engineer out to double check the tightness test and check for leaks around the hob connections. As mentioned if its worrying you open a window, for info with these tiny leaks they can vary so sometimes you can smell it, sometimes you cannot. A big leak would be a drop of several mBar and it would stink alot.

 

[sammathias]

0.5mb drop is tiny! Most engineers wouldn't even look for a leak. But as you can smell gas it needs to be investigated