That is a very astute and interesting question-I don't know but I'll ask my friends wife who has a PHD in chemical engineering from Texas A&M. She seemed interested when they visited my lab (old shop)

Just thinking outloud-if water boils at 212 degrees F and steam is produced only if the vessel used is pressurized. Then if the vessel in question is the electrolyzer  which is not enclosed but is pressurized by Hydrogen gas as well as pump-but how much pressure? The  temp doesn't exceed the temp of 156 degrees F under pressuraztion-how can flash steam be produced. I just trying to recall HS phyciscs.

Flash Steam is formed when high pressure/temperature condensate is suddenly decreased in pressure.

Therefore if one keeps the electrolizer below that tem/pressure relationship-no flash steam!

Hell I will have to study this one more! As well as get a rapid reply from Becky-she's the one with PHD.

Will keep you posted there are too many variables in the pressure of the condensate - the saturated water at the boiling point at the actual pressure - is reduced, the heat energy in the water is reduced to a level appropriate to the final pressure. The connection between the pressure and the boiling temperature can be found in the steam tables.

The energy - or enthalpy - made available when the pressure is reduced, will evaporate a part of the water, producing the flash steam.

Only a part of the condensate water evaporates as flash steam. How much depends on the enthalpy in the condensate at the initial and the final pressures.

The amount of flash steam produced during the pressure reduction can be expressed as:

w = (h_il - h_fl) / h_fe (1)

where

w = ratio of flash steam generated (kg flash steam / kg condensate)

h_il = initial liquid enthalpy (kJ/kg)

h_fl = final liquid enthalpy (kJ/kg)

h_fe = enthalpy of evaporation (kJ/kg)

Example - Flash Steam Generation

temp/pressure formula for me to give an honest answer.

The steam tables state that flash gas is not produced until reaching a temperature of 100.2 C (the pressure of the condensate - the saturated water at the boiling point at the actual pressure - is reduced, the heat energy in the water is reduced to a level appropriate to the final pressure. The connection between the pressure and the boiling temperature can be found in the steam tables.

The energy - or enthalpy - made available when the pressure is reduced, will evaporate a part of the water, producing the flash steam.

Only a part of the condensate water evaporates as flash steam. How much depends on the enthalpy in the condensate at the initial and the final pressures.

The amount of flash steam produced during the pressure reduction can be expressed as:

w = (h_il - h_fl) / h_fe (1)

where

w = ratio of flash steam generated (kg flash steam / kg condensate)

h_il = initial liquid enthalpy (kJ/kg)

h_fl = final liquid enthalpy (kJ/kg)

h_fe = enthalpy of evaporation (kJ/kg)

Example - Flash Steam Generation

pressure (kPa, kN/m2)	Temperature (oC)	Specific Volume (m3/kg)	Density - ρ - (kg/m3)	Specific Enthalpy of			Specific Entropy of Steam - s - (kJ/kgK)
				Liquid - hl - (kJ/kg)	Evaporation - he - (kJ/kg)	Steam - hs - (kJ/kg)
0.8	3.8	160	0.00626	15.8	2493	2509	9.058
2.0	17.5	67.0	0.0149	73.5	2460	2534	8.725
5.0	32.9	28.2	0.0354	137.8	2424	2562	8.396
10.0	45.8	14.7	0.0682	191.8	2393	2585	8.151
20.0	60.1	7.65	0.131	251.5	2358	2610	7.909
28	67.5	5.58	0.179	282.7	2340	2623	7.793
35	72.7	4.53	0.221	304.3	2327	2632	7.717
45	78.7	3.58	0.279	329.6	2312	2642	7.631
55	83.7	2.96	0.338	350.6	2299	2650	7.562
65	88.0	2.53	0.395	368.6	2288	2657	7.506
75	91.8	2.22	0.450	384.5	2279	2663	7.457
85	95.2	1.97	0.507	398.6	2270	2668	7.415
95	98.2	1.78	0.563	411.5	2262	2673	7.377
100	99.6	1.69	0.590	417.5	2258	2675	7.360
101.33	100	1.67	0.598	419.1	2257	2676	7.355
110	102.3	1.55	0.646	428.8	2251	2680	7.328

There wasn't enough room so I had to put up another post. Reading that steam table chart it appears on the surface you wouldn't get flash steam until that highlighted temperature/pressure on the steam table chart is reached. I am just trying to get your answer for all of us.

frogman11: TX. USA
 Finally learned How to edit this part! 1980 GMC truck 1/2 ton 350 CID with 3 spd. auto (test truck) 1995 Dodge Interpid 3.3 liter with overdive(next test engine) 2006 Toyata Highlander -off limits wife's car.

Don't forget, as long as the vacuum is going, the electrlyzers are not truly under pressure.

If we could create enough H.H.O. to build that kind of pressure, imagine what it would do for diesels.

Walking Eagle, Last of the Visionaries

Bakersfield, CA

You think you & Jon had a headake-hell my mind is  going a thousand miles an hour trying to get to the bottom of this. Tomorrow is another day!

I haven't had to read an enthalpy chart in over 30 yrs- as well as review my physics.

frogman11: TX. USA
 Finally learned How to edit this part! 1980 GMC truck 1/2 ton 350 CID with 3 spd. auto (test truck) 1995 Dodge Interpid 3.3 liter with overdive(next test engine) 2006 Toyata Highlander -off limits wife's car.

I wanted  to WARN you about that experiment you conducted but we Americans are a curious lot-that is what makes us different-we are sincere in our endeavors toward improving MANKIND and most of us don't like to be told -you can not do it-that's why we make progess-the will to explore and seek out new challenges despite the risk. Suffice it to express I am glad you'll OK! 

Since hydrogen is lighter than air (Hindleburg, LakeHurst, N. J. explosion) and when entrapped in enclosed container such as a hose and jar- a gas will exhibit the following characteristics:

1. A gas will travel within a confined space when ignited back to its source of ignition unless under pressure. You removed the pump.

2. Hydrogen was not used by US Navy ever because they found it was too combustible-hence Lighter-Than-Air (blimps) aircraft used Helium which was only found in Texas USA.

 I could go on and on but the point is Hydrogen gas is very very combustible that's why it works so damn good in our ICE's.

It behooves ALL MEMBERS OF THIS FORUM TO EXERCISE EXTREME CAUTION WHEN CONDUCTING EXPERIMENTS WITH HYDROGEN GAS!!!

P.S. My dad was a blimp pilot and aircraft powerplants mechanic in WW11 and I was trained in Under Water Demolitions.

Warmest Regards,

 

frogman11: TX. USA
 Finally learned How to edit this part! 1980 GMC truck 1/2 ton 350 CID with 3 spd. auto (test truck) 1995 Dodge Interpid 3.3 liter with overdive(next test engine) 2006 Toyata Highlander -off limits wife's car.