I went through a 1920’s catalog of their products and I don’t see any type of check valve at all. Only lots of safety valves and a few water relief valves.
In the past when steam trains let off excess steam at a station the noise could be extremely loud. The city of Boston looked into this problem as the complaints mounted up. Ashton Valve came up with a solution that proved very popular with the Train companies. A muffler! Same idea as on automobiles. And the blow back valves actually saved steam that used to be wasted.
Ashton patent steam gage.
Ashton Valve bought out the Boston Steam Gauge company in 1892 and entered the gauge market.
They immediately offered their own Ashton patent steam gage. The 1896 catalog page says the item was patented in 1891, a year before they even purchased the Boston Steam Gauge company, who they purchased for a particular patent BSG owned. I wonder if it’s the same patent?
The ideal alarm gauge was another practical item that could come in handy if the boiler room mechanic happened to fall asleep! When the pressure went too high, a loud alarm would go off.
Although it wasn’t among the most important product they produced(they rarely advertised whistles), Ashton Valve offered a number of them. Here are some catalog pages and some drawings.
What better way to make a gauge easier to read in a dark boiler room than to illuminate it? I found one from around 1900 where the bulb was fixed behind the gauge, not always practical. Here’s what Ashton Valve came up with.