Model Engine Maker

Supporting => Boilers => Topic started by: Jack3m on April 13, 2019, 12:05:42 AM

Title: FTT-12 safety valve?
Post by: Jack3m on April 13, 2019, 12:05:42 AM
My plans call for two "FTT 12" safety valves.  Cannot find anything about them.  System is supposed to be 100 PSI operating pressure, no advice on what pressure signifies opening of safety valve.  Supposed to pressure test this boiler to 250 PSI.  For reference this is the Harris Steam Donkey,
Title: Re: FTT-12 safety valve?
Post by: Jo on April 13, 2019, 08:17:52 AM
Bill Harris' book on page 128 says that all the castings, accessories are available from Power Model Supply Company. My guess is that FTT 12 is the part number of one of the ones they sell.

Looking at page 173 which shows the safety manifold it shows two threaded holes 3/8" * 32, spaced at 5/8". Any standard safety valve design would do but watch the size of the base hex as they are close together.

Jo
Title: Re: FTT-12 safety valve?
Post by: derekwarner on April 13, 2019, 09:47:39 AM
Jack....irrespective of the steam relief valve manufacturers design, such valves when used in model applications are covered by your Boiler Codes

Some Countries have far more rigorous design regulations, it would help if you registered your Country & region in your on-line profile

Simply, if your system is rated or recommended to operate at 100 PSI, depending on the Code...the relief valve must be rated for this value
By convention, with a twin steam relief valve installation, one valve is set at marginally lower that the other

This may sound complicated but simply means that the relief valve/s operates and limits the plant or system to less that the specified pressure

You have suggested that the boiler be tested to 2.5 x times the working pressure [this is a once only design test pressure test]

It would not be uncommon to remove standard system pressure gauge when the 2.5 WP [cold water hydro-static] test is completed

Your local model steam group will have a Boiler Inspector who will be able to confirm actual requirements for your locality /region etc  & the best person to start with

Derek

 
Title: Re: FTT-12 safety valve?
Post by: Jack3m on April 13, 2019, 01:52:20 PM
Interresting.  I contacted my State authority and got no response.  I think from what I read it is too small to be required to be inspected or registered.

As far as PMC, the safety valves are not that number and are only good to 60 psi. 

Lastly, I am not a club person.  I avoid that stuff like the plague
Title: Re: FTT-12 safety valve?
Post by: derekwarner on April 13, 2019, 09:24:08 PM
Well thats good Jack.....if you consider Clubs, Boiler Inspectors and Codes to be like the plague, :Jester: then you have answered your own question .....    :rant:
Title: Re: FTT-12 safety valve?
Post by: cnr6400 on April 14, 2019, 12:29:30 AM
Some excellent designs for safety valves can be found if you Google Gordon Smith's designs for some published by Model Engineer magazine a number of years ago. I built a set to his design for my Bill Harris steam roller , they were easy to make, and they really work well. He specifies to use stainless steel springs from Lee Spring, one of the biggest commercial spring makers worldwide, so there is no guesswork about the springs themselves, and no corrosion. Lee Spring Co are alive and well as of Apr 2019. Head office is in Brooklyn NY. Pair of small springs for my valves from Lee was about $10 a few yr ago. Postage cost more than the springs!
Title: Re: FTT-12 safety valve?
Post by: Jack3m on April 14, 2019, 01:18:19 PM
Well thats good Jack.....if you consider Clubs, Boiler Inspectors and Codes to be like the plague, :Jester: then you have answered your own question .....    :rant:
No just clubs, why the attack?
Title: Re: FTT-12 safety valve?
Post by: Jack3m on April 14, 2019, 01:20:26 PM
Some excellent designs for safety valves can be found if you Google Gordon Smith's designs for some published by Model Engineer magazine a number of years ago. I built a set to his design for my Bill Harris steam roller , they were easy to make, and they really work well. He specifies to use stainless steel springs from Lee Spring, one of the biggest commercial spring makers worldwide, so there is no guesswork about the springs themselves, and no corrosion. Lee Spring Co are alive and well as of Apr 2019. Head office is in Brooklyn NY. Pair of small springs for my valves from Lee was about $10 a few yr ago. Postage cost more than the springs!
Do  you have a link to Gordon Smith design?   Will google.
Title: Re: FTT-12 safety valve?
Post by: Jo on April 14, 2019, 02:26:27 PM
The Sutton Coldfield ME club page has all the Gordon Smith safety valve drawings:
 https://www.scmes.co.uk/images/Technical%20Information/SafetyValves/Safety%20Valves%20Master.htm

Just click on the list on the left to get the drawings.

Jo
Title: Re: FTT-12 safety valve?
Post by: Jack3m on April 14, 2019, 04:41:59 PM
The Sutton Coldfield ME club page has all the Gordon Smith safety valve drawings:
 https://www.scmes.co.uk/images/Technical%20Information/SafetyValves/Safety%20Valves%20Master.htm

Just click on the list on the left to get the drawings.

Jo
Thank You Jo. Yes thanks a bunch, never found that googling.  Dowloaded the whole pdf
Title: Re: FTT-12 safety valve?
Post by: Steamer5 on April 14, 2019, 06:03:44 PM
Hi Jack,
Polly Models sell the springs, stainless balls & drawings for Gordons designs. There is also a bunch more designs on there site than you've just downloaded. Unfortunately no pictures or outline drawings. They also sell complete safety valves... there description of these may take a bit of working out.

Cheers Kerrin
Title: Re: FTT-12 safety valve?
Post by: rspringer on April 14, 2019, 08:56:55 PM
The safety valves should open at 100 psig and a good one will close at about 90.  To get real work out of the donkey you will need to be between 85 and 100 psig.  Washington is one of those states that wants to have their hand in our hobby.  I am using their requirements in designing a boiler for the Lombard that is on my list.  Locoparts.biz has off the shelf valves.  They may be a little large for the donkey.  You don't need a very large one.  are you going to fire on coal or propane?  When I fire on propane I have to work to get the safety to lift.  Always test the safety at each firing.  After the initial hydro test, an annual test of 150 is customary.  Kozo also has the drawings for a nice sized safety.  if you build one yourself remember they act different on steam vs air.
Title: Re: FTT-12 safety valve?
Post by: Jo on April 14, 2019, 09:48:25 PM
And the link to the information on the springs for your safety valves:

https://www.scmes.co.uk/images/Technical%20Information/Non%20Pop%20Safety%20Valve%20Tables%20info/Ready%20Wound%20springs%20safety%20valves%20Tec%20page%20.pdf

The second page has all the pressures and sizes worked out for you  ;)

Jo
Title: Re: FTT-12 safety valve?
Post by: derekwarner on April 14, 2019, 11:33:45 PM
Jack....I have no knowledge or understanding of model steam rules for your land or location?.....however in Australia, if you intend to use or display live steam in public, you must be covered for liability

Steam authorities will not deal with an individual and refer you on to registered Boiler Inspectors who are generally associated with Steam Clubs

So in Australian it's catch 22....display in public = belong to a club + use the registered Boiler Inspector + have your boiler tested, certified & registered in accordance with the Rules of the respective Pressure Vessel Code ........nothing more, nothing less....

Derek
Title: Re: FTT-12 safety valve?
Post by: Jack3m on April 15, 2019, 01:53:18 PM
Derek, I have read the legislation for my state and region.  It appears that the size of my boiler is less than those required to be inspected and certified in my State.  I tried contacting my local authority and got no response in return.  There is a local club and some members there are members here, but we have multiple state jurisdictions to worry about....that club is in another State with another set of rules.  This gets pretty confusing and frustrating. 

My goal is to make something.  I have no intention of doing public displays and usually the weather is incompatible for my health issues anyhow.  I will sell it as an uninspected boiler/system when I have completed it and played with it a bit.  That finances the next project.  I will never consider being unscrupulous.

I am trying to do the correct thing, safely.  Frankly this boiler I am making is way overdesigned.  (I have a mechanical engineer for a son, so I get good knowledge, albeit not specialized in boiler technology.)

The clubs thing.  I have had a lifetime of clubs, serving clubs, being officer, etc.  My health no longer can tolerate all that, much less the usual evening meetings, tho the local club is on a Saturday, but quite far for me to go, and I do like to see my wife on weekends as I am quite fond of her.  We get up at 0400, thusly we go to bed early 2000 at the latest.  This also is not conducive to club participation.  I do participate in online forums like this to interact with others which has become my version of 'clubs'.  It is not that I do not care about safety, I was a paramedic and saw everything, including industrial boiler failure.
Jack
Title: Re: FTT-12 safety valve?
Post by: Jack3m on April 15, 2019, 02:09:50 PM
  are you going to fire on coal or propane?  When I fire on propane I have to work to get the safety to lift. 
Probably propane as I have a Century burner or  3 laying around not in use.  Never mind the fact  if I want coal here I have to buy the stuff to barbecue.
Title: Re: FTT-12 safety valve?
Post by: Jack3m on April 16, 2019, 06:51:02 PM
Shucks, folks got me worried now.  Even though I have almost all the parts made for the boiler to be welded together, I am now considering just selling the mechanical, the skids (which I still have to make), and the parts for the boiler to be made and move on to my next project. 

I am much more interested in the making than the playing or the selling or showing it off.  I just like to make stuff and have folks appreciate it. :noidea:
Title: Re: FTT-12 safety valve?
Post by: Jo on April 16, 2019, 07:23:27 PM
I am much more interested in the making than the playing or the selling or showing it off.  I just like to make stuff and have folks appreciate it. :noidea:

Totally agree  :ThumbsUp:

Jo
Title: Re: FTT-12 safety valve?
Post by: rspringer on April 16, 2019, 08:05:30 PM
https://s3.amazonaws.com/ClubExpressClubFiles/96970/documents/Miniature_Hobby_Boiler_Guidelines_April_5_2011_Revision_3rd_Edition_4th_Rev_-_Copy_1252729329.pdf?AWSAccessKeyId=AKIAIB6I23VLJX7E4J7Q&Expires=1555438414&response-content-disposition=inline%3B%20filename%3DMiniature_Hobby_Boiler_Guidelines_April_5_2011_Revision_3rd_Edition_4th_Rev_-_Copy.pdf&Signature=K%2Fr8EDxKm5vnNWauQ5t0fnhgi%2Fc%3D
This is what I found about Washington state boilers.  I has some good formulas for stress calculations.   
Title: Re: FTT-12 safety valve?
Post by: Dan Rowe on April 16, 2019, 09:08:12 PM
Jack, I just checked my old Power Models catalog and FTT-12 is for a 3/4 scale locomotive with a 3/8"-32 thread. There is no other info about the valve.

Unfortunately, Power Models is long gone so another source will have to be located.

Dan
Title: Re: FTT-12 safety valve?
Post by: Jack3m on April 17, 2019, 01:00:57 PM
Thanks Dan, I am more worried about certification.  I think I can make one easily enough(valve).  I am going to go ahead and build the boiler and worry about it after the fact, at least I will get the play of welding it all up and I do like to weld.  M State regulations confuse me to all get out.  Waiting on member of local club to contact me.....Thanks folks.
Title: Re: FTT-12 safety valve?
Post by: Dan Rowe on April 17, 2019, 04:04:40 PM
Jack, The boiler laws for Washington State are here:
http://www.lni.wa.gov/TradesLicensing/Rules/files/boilers/BoilerLawBook.pdf

The section of interest is "70.79.080 Exemptions from chapter."

Your boiler meets the definition of a miniature hobby boiler, but this wording says that it has to be certified by an inspector to be exempt from the chapter.


"(14)(a)(i) Miniature hobby boilers that have been certified by an inspector as of June 7, 2018; or
(ii) Miniature hobby boilers that have not been certified
by an inspector as of June 7, 2018, but that receive certification from the chief inspector prior to being placed in service"

I am not a legal expert I am an engineer, but that is how I read it.

Dan
Title: Re: FTT-12 safety valve?
Post by: Jack3m on April 18, 2019, 01:01:09 PM
that is what I read too