On Sat, 31 Dec 2005 12:38:18 GMT, david lang wrote:

wrote:
I have recently seen the sulphuric acid to clear blocked drains.
Having googled around, it seems I should not mix the 2.

Absolutely not!!!!!!!! A serious explosion could result, covering all &
sundry with nasty stuff.


Even I wouldn't do that.

You use caustic to braak up organics - especailly solidified fat - and
sulphuric to smash through limescale.

Mixed togrther they neutralise each other.

After a short period of pyrotechnics.

High school chemistry suggests that sodium sulphate and a LOT of heat will
be the result.

I am not sure if I know ANYTHING that sodium suplhate is good for..

If you had used brick acid (hydrochloric) you could at least have made some
salt....:-)



I am trying
the caustic soda today followed by boiling water and detergent.

If that fails, how long should I wait before i move on to the acid?

If the drain doesn't unblock, try the caustic again or use rods. There will
still be a highly alkaline presense in the drain, so the acid will react
with it.


When doing anything with caustic, once the blockage has cleared always
flush with gallons of fresh water. The public drains can handle mild alkali
in quantities better than a gob of conentrate going past, which can get
trapped and cause problems.

Despite dire warnings, I once again used castic and hot water to clear the
christmas grease out of the U bend, and can report that as usual I did not
end up in hospital.

Use of _boiling_ water from a kettle is a bit of a last resort, and you do
get superheated alkali vapour and a lot of splashing, so do that carefully
and test outside first with glasses and old clothes on so you know what to
expect.

Splashes on skin will burn and need washing with lots of cold water fairly
immediately. The skin will feel soapy, but no lasting damage ensures. Eyes
are a different matter. lots of hot water and off to A & E weher they can
at leats give you pain killers - corneas do redrow, but hurt like sin while
they do. Ive never had alkali in my eye, but I have had branches and
throrns scratch the cornea and cause an extremely painful condition, and
infection too.

Splashes on cloths bleach them totally and generally rot the fabric too.
..
The secret is to get hot caustic to the site and let it stay there and do
its work., If the drain is totally blocked, this may not work.

What I do in cases of dire ncessity is this.

I open up the sink plug, and fill it to the brim with solid castic soda
crystals.I keep adidng them until the whole drain is as full as it can get.

From a distance, I pour boiling water from a kettle on,. a little at a
time, at arms length, because it is a VIOLENT flash steam generator, and
100C caustic splashes HURT. This boiling caustic mixture seeps down, and
you can actually hear it boiling inside the pipes, and you get little
geyser type eruptions from the sink hole. Thse are usaully vile smelling,.
brown gunk and styill highly corrosive. Treat with *utmost* respect.

If the drain doesn't clearr, I repeat as often as is necesary until the
high concentration hot caustic has travelled to wherever the blockage is.

I'd say this brutal technique works 90% of the time.

However there are exceptions.

- I have had 'female waste' blocking low fall sewage systems outside to a
septic tank, with high ground water levels leadng to high tank levels. Here
I used reverse flushing from a manhole - pushed a hose up the pipe and
probed the turdiness until all the big bits had floated past.

- I have had an old toilet so scaled up that female waste and turds and bog
paper got stuck in its U bend.Here caustic made short work of the turds,
but some industrial acid from a friend - sulphuric IIRC - left in over
night dissolved what scale there was - we ended up pushing HUGE chunks of
turd and urine and scale composite down the drain in due course. Once that
was done the other problem did not reoccur. The loo also looked sparklingly
new again.

- I have seen tree roots push and fracture old clay pipes, and then get
inside. This is really bad news. It can happen with plastic too - the
joints may spring, and the roots then charge off towards this lovely
nutrient and water supply. Sometimes chemical attack helps keep it at bay,
but really, having dug one up in that condition, I'd say that is the only
real answer.





Dave