3" Fowler A7 on Steam Test 

Build one

When it's your Engine you can do what you want with it. Those valves are better than Ramsbottom or Salter safety valves because these have a positive reseat and don't continuously weep or leak steam until you're 40 pounds below set point. These open, fart for a second, then shut completely which is what you want. Saves steam, thus saves water and fuel, and doesn't wear out the valve. Ramsbottom valves tend to wear prematurely because the seats become wire-drawn from steam constantly blowing past. The only other two high quality valves in this scale that would accomplish the same positive reseat function without farting are the valves from Jubilee Fittings in the UK, and in America, Eccentric Engineer makes locomotive style miniature Consolidated Valve Co. Safeties which also pop without farting. They're for 1" scale locomotives but would be equally at home on a 3" scale traction Engine.

@@steamandsmoke97 Wow chill out mate! Hells Teeth dude.

@@NathanielKempson All true though , anyhow Fowler Leeds, Burrell's follow.

The raspberry sound is simply down to the velocity of the steam escaping through the gap available having matched the oscillation frequency of the ball on its seat. Increasing the internal bore of the valve or, maybe using a fractionally larger ball for the same pressure ought to avoid the tallying of the vibration frequency with the escaping steam. It’s an easy mod, but this was this locomotives very first steam test to find out if anything needed altering. 🙂

@@TheSteamWorkshop Always wondered how to fix that issue. Not that I have a steam loco (yet) but handy to know. thanks.