Hi @Tony Press They do look like they may belong on a blowlamp. combined filler cap, air-release valve, and SRV.... Best Regards, Kerophile.
Hi, these are two similar looking Svea filler cap/SRV assemblies (New Old Stock) for blowlamps. The petrol/gasoline types do not have air-release valves for obvious reasons. Best Regards, George.
Looks like they have reverse threads. Makes sense, as you wouldn't want to try and release air slowly via the pressure release, which is on the same axis, and accidentally unscrew the entire filler cap instead.
So that is a vent screw on top? reverse threads, how observant and clever. (logical explanation too, logic: method to arrive at wrong conclusion with confidence hehehe) the one on the right differs from the other 3 and maybe? one on right is reverse thread? call me goofy but the 3 on the left do not look reverse to me?
Looking more closely, it does seem that only the one on the right is reverse thread. Curious to hear back from Tony on that one.