Forum: F-16 Design & Construction

Joined: Feb 01, 2007 - 02:38 AM Posts: 0 Status: Offline

H70 is also used in the U-2 EPU.

H70 is the blend of hydrazine and water (70% hydrazine and 30% water) and conforms to the requirements of specification MIL-PRF-87930A

Links to Hydrazine information:

MIL-PRF-87930A - http://www.desc.dla.mil/DCM/Files/MIL-PRF-87930A.pdf

NASA Hydrazine (100%) Specifications - http://propellants.ksc.nasa.gov/n2h4spec.htm

Material Data Safety Sheet for Anhydrous Hydrazine (>64%) from Cornell University - http://msds.pdc.cornell.edu/msds/msdsdo ... m86166.htm

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Bix, you never cease to amaze me. Come to think of it, no one here does! I'll check the links and thanks again for the time and effort! Very Happy

I don't know everything about reading an MSDS, but from what I understand all I can say is #$%@ Shocked

!!! As my dad would say, that stuff is truly "Ethyl Methyl Bad S***"! Not just is it incredibly toxic, but they seem to indicate that you should be seriously concerned about ANY source of ignition - even sunlight!

Thanks for the info and I think I'll stay upwind of the Vipers at the next airshow I go to! Wink

Joined: Feb 01, 2007 - 02:38 AM Posts: 0 Status: Offline

You only have to worry about the Vipers if the fire trucks follow them back in and you hear a soft, pop, pop, pop, pop, noise comming from the jet. That would be the small amounts of H70 injected into the engine bleed air to maintain EPU RPM during operation near engine idle. Normally they will taxi the jet to a safe location based on current wind conditions, until the Hydrazine Response Team can safe the system.

On a static Viper you would look for a water type substance dripping from the RH strake area, with a distinct ammonia odor, by then you are over-exposed, but move away from the Viper to limit your exposure. Very Happy

There is a little orange leak detector in that area of the strake that will turn dark purple or black if there is a leak, but to see it you would be too close to be truely "Safe". Why did they bother!?

I believe the Pilots are to go to 100% oxygen during an EPU activation to maintain a safe breathing supply.

Ammonia & Hydrogen are the major by-products of burning Hydrazine.

Last edited by parrothead on May 19, 2004 - 11:30 PM; edited 1 time in total

Just kidding about the airshow Vipers bix, but thanks for the info on where to look! Now I know when to grab any people nearby and alert the security and fire crews. Cool

As for the little orange leak detector, this is the military we're talking about. No offense to the grunts and drivers, but since when was common sense legal in the upper echelons? Laughing

Seriously, I think it's just a good idea to have some easy way other than smell to tell if the stuff has spilled.

Joined: Feb 01, 2007 - 02:38 AM Posts: 0 Status: Offline

Another link to Hydrazine info from the CDC's Agency for Toxic Substances and Disease Registry - http://www.atsdr.cdc.gov/tfacts100.html#bookmark02

The ATSDR toxicological profile succintly characterizes the toxicologic and adverse health effects information for the hazardous substance described here - (4 Meg file!) - http://www.atsdr.cdc.gov/toxprofiles/tp100.pdf

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Thanks for the info and I think I'll stay upwind of the Vipers at the next airshow I go to!

Because crew chiefs are viciously defensive about their jets any leaks under the jet would be quickly identified and either cleaned or caught. So don't feel as though you need to give the F-16 space due to it's emergency system.

Great reading again, Bix! IDCrewDawg, as I said before, I was just kidding. Smile

No offense meant to the CCs - they're a great group of guys and they do a great job! No offense meant here, but I've been to many airshows where I haven't seen pilots or maintainers around some of the jets for a while. When I say that I now know what to look for, I'm just saying I'm glad to know what's up in a worst case scenario. I guess it's the boy scout in me who always wants to "Be Prepared"! Very Happy

Hi guys,

I know that hydrazine is also used in the space shuttle.
NASA uses it when they are in space to control the shuttle.
The boosters in the nose are used for that.
You can't use any other fuel type because due to the lack of oxygen.
so that is why NASA uses the same stuff.

I have heard that it's used for the EPU only because it hase such a rapid combustion and take the generator really fast to it's desired RPM's.

I have known people too that have been fired upon and had a shower from hydrazine when they where stupid but all they have to do is see the doc and give blood to see if it's out of thier system and how much they got in to the system.

Other than that I don't like hydrazine.
because it's clear and when you get to your jet in the morning and there was some dew that night you never know it's hydrazine hanging on the exhaust or not and you don't want to smell it neither.
some say it's a amonia some say it's like a rotten eggs kindda smell.
I never had to smell it Smile

greetz henk

Joined: Feb 01, 2007 - 02:38 AM Posts: 0 Status: Offline

The Space Shuttle Reaction Control System uses Hydrazine, but it's not H70.

It's almost pure Hydrazine, and dires over a catalyst that allows it to ignite without oxygen or a spark.

If you notice when the shuttle lans one of the first things they do is remove the remaining fuel with the support trucks that race down the runway to catch it.

Safety first!

Newbie Joined: Jan 23, 2004 - 03:07 PM Posts: 16

Quote:

The Space Shuttle Reaction Control System uses Hydrazine, but it's not H70.

Hydrazine is H-70 there is no difference. The same stuff that is in the shuttle is in the F-16, U2, B2 and what other aircraft is out there that has it.

[quote="mark"]It's a chemical reaction to the Iridium in the decomposition chamber. It rapidly breaks down into hot gases (1600 degrees) that are ported over a turbine (much like a water wheel).The nitrogen is used to pressurize the H-70 fuel tank, it never mixes with the H-70 (there is a piston separating the two). The speed is roughly regulated to 75,000 rpms. Hydrazine has been used as a rocket fuel for over 40 years now. I would more leary of some of the other chemicals used in fuel system sealing than H-70. Its an old wives tale that "if you smell it your dead".[/quote]

Mark is right about the wives tale. When I was fact checking for One Desert Jet Turner, I came across a paper by William D. Christensen and Joseph A. Martone, "The F-16 Aircraft and Hydrazine -- An Industrial Hygiene Perspective." SAE Technical Paper Series 851971 (October 1985): 1-5. You can probably find it on fiche at a good local reference library.

Before I read this paper, I thought hydrazine was going to turn out to be a long term hazard for the folks that had to operate around it a lot, but their research shows we all should sleep healthily into old age. I hope so.

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Hydrazine is H-70 there is no difference. The same stuff that is in the shuttle is in the F-16, U2, B2 and what other aircraft is out there that has it.

No offense, but I'm not so sure. According to this, there appears to be a couple of types.

http://www.desc.dla.mil/DCM/Files/MIL-PRF-87930A.pdf
Thanks for supplying this resource bix!

Another question-

Quote:

It's almost pure Hydrazine, and dires over a catalyst that allows it to ignite without oxygen or a spark.

I understand ignition to mean the beginning of combustion, and combustion to be rapid oxidation. How is ignition possible without oxygen? Does this actually refer to a rapid, highly exothermic reaction which requires no oxygen?

One last question in this post - the combustion temperature of hydrazine has been mentioned several times as being very high. How does the F-16's EPU deal with these temperatures? Do the materials it's made out of allow for these extreme conditions or is there some other provision?

Active Member Joined: Apr 08, 2004 - 10:40 PM Posts: 201

Quote:

One last question in this post - the combustion temperature of hydrazine has been mentioned several times as being very high. How does the F-16's EPU deal with these temperatures? Do the materials it's made out of allow for these extreme conditions or is there some other provision?

Its a combo of both, There are heat shields completly rapped around the EPU, I have seen numerous time when we purge an aircraft after a IFE that fired its EPU, the upper heat shield covering the gas generator is completly scourched.

How dangerous is Hydrazine after a F-16 crashs? Does it burn up or do the Haz people need to secure the site similiar to what EOD does. The reason why I'm asking is yesterday I saw a pic from Indiana that showed some fire fighters standing real close to the wreckage and to make things even more intersesting two flares were going off as they stood there.

Forum: F-16 Design & Construction

The EPU - how does it work and why hydrazine?