- This topic has 8 replies, 5 voices, and was last updated 20 years, 10 months ago by bungie.
24 Sep 2000 at 2:39 am #273562Anonymous
I’ve purchased a new washer & on the first page is a warning “Under certain conditions, hydrogen gas may be produced in a hot water system that has not been used for 2 weeks or more. HYDROGEN GAS IS EXPLOSIVE. If the hot water system has not been used for such a period, before using the washing machine, turn on all hot water faucets and let the water flow from each for several minutes. This will release any accumulated hydrogen gas. As the gas is flammable, do not smoke or use an open flame at this time.”
Under what conditions will this H2 gas be produced? How common is this problem?
24 Sep 2000 at 5:40 am #288029GuestParticipant
Hydrogen is a component of water, thus H2O is well known. Less commonly known is the meaning of Ph. This is a balance of hydrogen ions (H+) and hydroxyl ions (OH-). At any time there is free oxygen in water kept in balance by the chemical combinations within the water. Low Ph (below 7 on a logarithmic scale) is an acid condition. High Ph (above 7) is a basic condition.
Other gases are present in water depending upon the water source. Well water often contains hydrogen sulfide that smells rotten. Chemical reactions separate hydrogen from the hydrogen sulfide. Chlorine may bond with oxygen from a hydroxyl, leaving hydrogen. Other chemical reactions can take place. Reaction time is doubled for every ten degree rise in temperature, so a water heater is an ideal location to collect hydrogen.
Actual problems from this collection occur rarely, but the nature of our litigous society creates a necessity to warn of any possible danger.
24 Sep 2000 at 6:24 am #288030SylvanLMPParticipant
Hi Kathy, from what I remember from my apprenticeship training A LONG TIME ago
There is no such thing as H+ in solution, since that would basically be just a proton. aqueous acids (water based, as most are) are actually H3O+, which isnt explosive at all. the term pH should really be pH3O+, but they use pH out of convention. also, chlorine bonding with oxygen will NOT make a hydroxy group, there is no chlorine in hydroxy (OH-)
Hydrogen is produced when a metal comes in contact with acids (except for nitric acid). You need pretty concentrated acid to form enough hydrogen to be of any real danger.
Actual problems from this collection occur rarely, but the nature of our litigous society creates a necessity to warn of any possible danger. EXACTLY
24 Sep 2000 at 6:48 am #288031RichardParticipant
You must remember what pH actually is. Its the negative logarithm of the hydronium concentration (H3O+)
As such, a change of 1 pH unit constitutes a 10-fold change in acidity/alkalinity.
pH of 7 is the same as a molarity
of 1.0 10-7M H3O+, which is still quite low
24 Sep 2000 at 10:05 am #288032bungieParticipant
Its just the anode doing its job.
As they said above
“Actual problems from this collection occur rarely, but the nature of our litigous society creates a necessity to warn of any possible danger.”
But it is possible for a faulty washing machine to arc on a contact and ignite the gas. Very rare, but possible
24 Sep 2000 at 4:11 pm #288033RichardParticipant
You must remember that a simple arc passing through water will not produce hydrogen gas. A strongly ionic media is necessary, and typically that is sulfuric acid. THEN, when a voltage is applied you get SOME seperation of water into its constituents, molecular hydrogen (H2) and oxygen (O2).
24 Sep 2000 at 7:21 pm #288034SylvanLMPParticipant
Hey you chemists, as an apprentice we were taught just the very basics as we (plumbers) do come in contact with several types of “gases” from sewer work and domestic water with all kinds of great stuff added.
If I really had to get a lot of detail about “Chemistry” Id RUN TO A HOME CENTER and ask the stock Clerk to give me the molecule break down and other comparability problems with drainage and water filtration systems.
Like one Jackass told me he went to a home center to ask the guy behind the counter what could possibly be making noise in his home miles away sight unseen he wanted this maven to explain it.
Go figure. Think EL Cheapo would even give the guy a tip?
Kathy if your really worried take a water sample to a lab to find out exactly what is added to your water supply. Good luck
24 Sep 2000 at 10:14 pm #288035RichardParticipant
TiegerLMP: one problem with your post, hydrogen gas is not soluble in water. in fact one way they produce hydrogen is by mixing zinc with hydrochloric acid, and collecting it under water into an inverted bottle. But I agree with you, those home depot guys are great. They work there not because they couldn’t hack it in their field, but they want to supply a service for “immigrant wages’
24 Sep 2000 at 10:40 pm #288036bungieParticipant
Water and gas enter the washing machine. The lid is down, the gas sits in the machine. The cycle goes from fill machine to the wash cycle, as the armature turns against the brushes in the motor and any switches start to work, “it is possible for a faulty washing machine to arc on a contact and ignite the gas”
The gas is produced by the anode dissolving as it protects the tank
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