"Spark Sentry" Spark Arrestor

Canadian National Railways 1277, Prince Rupert, August 26, 1959. According to S.M. Huston, a Southern Pacific mechanical officer, the SP seems to have done more than any other road to research the problem of exhaust sparks.


Mr. Huston was quoted in the June, 1960 "Railroad" magazine “exhaust spark emission occurs at high load and believe to be due to the burning and dislodging of carbon deposits in the exhaust passages.”

I believe these to be "Spark Sentry" spark arrestors, jointly developed by Standard Oil Company and Southern Pacific. Open to discussion. What is undeniable is that exhaust gasses spin in a uniform cyclonic manner within the horizontal manifolds, where they rotate until they burn out or disintegrate. And they are ugly!

Furthermore, these devices are found only on Canadian National Railway locomotives. They were installed on  SW1200 (Shown here are SW1200RS) GMD1 and GP9  series locomotives.

You may be surprised to learn that “spark arrestors” are not optional in many jurisdictions. In British Columbia, with railroads routinely running through remote areas where a spark induced fire could be wildly out of control before being discovered, spark arrestors were not an option.

Indeed, here is the text of Washington Administrative Code, Title 332, Chapter 332-24, and Section 332-24-005, to whit:

(g) Locomotive spark arrestors for use on logging, private or common carrier railroads operating on or through forest land must meet the performance levels set forth in the Association of American Railroads (AAR) Recommended Practice, "Standard for Spark Arrestors for Non-Turbo Charged Diesel Engines Used in Railroad Locomotives."

As with all locomotives operating on the western extension from Red Pass Junction to Prince Rupert, Flexicoil trucks – for lightweight rail operation – were gradually replaced with Bloomberg’s as rail was upgraded.

Railroad Stuff: Canadian National Railways 1277, built by General Motors Division (GMD) at London Ontario, as an SW1200RS, road class GR-12k, 1,200 hp, in September 1957, serial number A-1173. Retired 1983 (?)