Boiler water PH

[daveaf]

Ive just tested the water in my central heating system for PH and it came back at about 7.5. (Almost Neutral).

Im sure i read somewhere that the water should be slightly alkaline (PH 9). I have access to all the appropriate chemicals required to alter boiler water PH, so my question is:

Is the PH ok at 7.5 or should I alter it?

We run our industrial boilers at PH10 but this is at 99Bar, so im not sure if mine is OK.
System has been extensively cleaned and flushed, heat exchanger has been descaled in Sulphuric acid and washed. Fernox inhibiter has been added and water is crystal clear. I just want to be sure Im not gonna get any more issues later down the line.

 

[hect]

Dont put ANYTHING in your system at all unless its agreeable with your boiler manufacturers instructions - some addatives can damage HEX and cause all kinds of problems!!

 

[Agile]

We run our industrial boilers at PH10 but this is at 99Bar, so im not sure if mine is OK.

System has been extensively cleaned and flushed, heat exchanger has been descaled in Sulphuric acid and washed.

What model of boiler operates at 99 Bar?

If the problem was lime scale then suphuric acid has little effect as calcium sulphate is insoluble.

We usually use sulphamic or hydrochloric acid for lime based compounds in domestic boilers.

Tony

 

[daveaf]

Its a super heated steam plant in an oil refinery. puts out 800 tonnes an hour of super heated 99 bar steam to run the refinery. its 130 feet tall
It runs on demineralised water with an additive to boost the PH to about 9.5/10.

The acid certainly dissolved what build up was inside, it was 98% sulphuric acid.

So is a neutral PH best for domestic heating systems.

 

[namsag]

Have a look here www.sentinel-solutions.net/en/heating/X100/questions

 

[daveaf]

Have a look here www.sentinel-solutions.net/en/heating/X100/questions[/QUOTE]

Thanks for the link, so PH neutral is best. I will leave it alone then and check it again in a year or so.

 

[Onetap]

It is usually alkaline, pH 8.0 or so. Galvanic corrosion becomes a problem if the water is acidic. However, it depends on what is in the corrosion inhibitors and the manufacturers won't disclose that.

There is also an oxygen scavenger componet in the inhibitors. If you adjust the pH with sodium hydroxide, you should also have a tewst kit to check the concentration of the oxygen scavenger. Sodium sulphite at 300 ppm seems to ring a bell.

Some modern inhibitors use sodium molybdate as the corrosion inhibitor which doesn't depend the pH being >7.0.

 

[Tipper]

Not wishing to be rude but if you're running steam boilers at those conditions you need to talk to an industrial chemist familiar with steam boiler water dosing.

Using this chat room for advice on this topic could be very dangerous and leaving it for a year before checking is unbelievable! Do yourself a favour and get some professional advice. Doesn't the company employ chemists?

 

[namsag]

HE is on about his boiler at home not the power station

 

[Agile]

The acid certainly dissolved what build up was inside, it was 98% sulphuric acid.

If you have a Wickes 50 then I think thats a cast iron heat exchanger in which case with conc sulphuric it would have been very likely to dissolve the heat exchanger itself!

Tony

 

[WDIK]

The acid certainly dissolved what build up was inside, it was 98% sulphuric acid.

If you have a Wickes 50 then I think thats a cast iron heat exchanger in which case with conc sulphuric it would have been very likely to dissolve the heat exchanger itself!

Tony

as i used to work with power and process steam, servicing and NDT work, the example is fancifull 99bar, 800 tons an hr, would be the size of the isle of white.

you may work at an oil refinery and have seen things but learn to get the overheard fact right.
I used to do fort dunlop, and there they had 12 55,000lb/hr babcock wilcock superheaters, one of the largest ever boiler houses.

wish to carry on?

 

[daveaf]

Yes lets carry on. Are you saying that my information is incorrect. Why would I want to make up something like that? The boilers are John Brown items, they run on a mixture of gas and fuel oil, they produce 400 tons each of 99 bar steam and are connected together to run A steam turbine generator producing 69 Megawatts. they generator exhausts steam at 9 bar which is used to run the refinery.

All i did was post a question about my home boiler PH and you decide to act like a clever **** and contest my information.

BTW the Wickes boiler I have is an old one which has a copper heatexchanger, not cast iron.

 

[WDIK]

It runs on demineralised water with an additive to boost the PH to about 9.5/10.

The acid certainly dissolved what build up was inside, it was 98% sulphuric acid.

thats alkline, ph below 7 is acid