Natural Gas - calculating pressure drop

[cardigan]

Watching.

That's nice to know

 

[chris watkins]

Watching.

Hello, it's the eye-in-the-sky, again !!! am I in the pooliverse? (Perishers)
(no gas seals being removed here, we are all taking care, info is freely out there, so not the sole preserve of GSR !)

 

[chris watkins]

Because I've found a formula to calculate drop in gas pressure and the formula requires the flow rate

Trick will be to find out how much gas each appliances will be using running flat out (kW input), then convert to amount of gas required to meet this. (clue = look at your gas bill for how much you get out of one one cubic Metre)

 

[vern]

21mbar working pressure at the meter then should have 20mbar on the inlet to the boiler. BS6891

On these figures 18.5 Mbar at gas valve inlet as you are allowed 1.5 Mbar, across the internal gas Pipe and isolation valve on WB boilers!

 

[TBServices]

To better ensure that two people taking a shower at the same time (in separate showers!) both get emough hot water

This will never happen with any standard combi, 38kw or otherwise.

And you shouldn't be concerning yourself with gas rates, pressures and formulas relating to such things

 

[Reg Man]

On these figures 18.5 Mbar at gas valve inlet as you are allowed 1.5 Mbar, across the internal gas Pipe and isolation valve on WB boilers!

Yes Vern thats what WB say. Thats why I said on the inlet and not at the boiler inlet test point. I put an inlet test point just before the boiler isolation valve when I feel necessary on marginal jobs, it certainly prooves the pressure drop through the boiler valves and pipework.

 

[vern]

Yes Vern thats what WB say. Thats why I said on the inlet and not at the boiler inlet test point. I put an inlet test point just before the boiler isolation valve when I feel necessary on marginal jobs, it certainly prooves the pressure drop through the boiler valves and pipework.

Yep good practice regards the test point just below appliance, had a 2 Mbar drop, from this point to gas valve inlet on an 837 combi, but some of this is the fan suction having an effect too, hence the tolerance.

 

[cardigan]

What you really need is a "man's formula" not these ready-reconer's you will be requiring Pole Formula.
Please see attachedView attachment 10554

Dr Poles formula can be found on page 10 of this doc and you will see that the root factor covers both the numerator and the denominator . [DLMURL]http://www.mech.hku.hk/bse/MEBS6000/mebs6000_1011_04_steam.pdf[/DLMURL].

And, transornation of the formula for H gives h = ( s * l * q^2 ) / ( 0.0071^2 * d^5) i.e. D to the power of 5 not D times 5

 

[cardigan]

shouldn't be concerning yourself with gas rates, pressures and formulas relating to such things

I shouldn't but you should. I expect a 'professional' to come to my house and show me a mathematical equation proving that I need to pay to put in wider pipe. I expect that someone who is charging £50-70 an hour can do that. Is that asking too much?

 

[mfgs]

I shouldn't but you should. I expect a 'professional' to come to my house and show me a mathematical equation proving that I need to pay to put in wider pipe. I expect that someone who is charging £50-70 an hour can do that. Is that asking too much?

What happened to trusting someone who clearly knows what they are talking about. If you have a problem with your car do you go down to the mechanic and make him prove his diagnostic skills in order to satisfy you that he isn't taking you for a ride? I know if I had someone ask me for a mathematical equation to prove that the gas supply needed upgrading I would tell them to stick the job up there arse. Anyone that even entertains having you as a customer is clearly a much more patient, understanding man than me. Either that or they are desperate for work.

 

[bewsh]

I'm pretty sure Worcester suggest upgrading the first 3m of gas pipe from the meter to 28mm

 

[Reg Man]

I shouldn't but you should. I expect a 'professional' to come to my house and show me a mathematical equation proving that I need to pay to put in wider pipe. I expect that someone who is charging £50-70 an hour can do that. Is that asking too much?

I know your sort. The guys on this forum have been more than helpful. Vern posted a mathematical formula for you. I really do not know what more you want. If you want a plumber to come round with the total calculation formula; I will come round and it will cost you £200 per hour. Or Some one else can come round with a screw driver leak detection fluid and manometer for £50 per hour. I guess the latter is more likely.

 

[dancinplumba]

I know your sort. The guys on this forum have been more than helpful. Vern posted a mathematical formula for you. I really do not know what more you want. If you want a plumber to come round with the total calculation formula; I will come round and it will cost you £200 per hour. Or Some one else can come round with a screw driver leak detection fluid and manometer for £50 per hour. I guess the latter is more likely.

too cheap at £200