Get rid of antique LP regulators and install brand new modern ones.
There is probably a regulator inside your furnace, perhaps inside your
fridge and also under the cooktop of your range. These also can become
unreliable with age and long use. Try to replace them if you can find new
ones that will fit.
The main regulator is usually set at 11" (less than 1/2 psi) and appliance
regs at 10".
Al