Spark Arresters are a fairly new but important subject for consideration within our hobby. Mainly, this applies to railway locomotives and traction engines burning wood or coal, where the emission of sparks and cinders could cause injury or complaint to other persons.

It is no longer enough to display a sign saying that "Steam locomotives can emit hot cinders and oil". We must be proactive to protect both our members, and particularly passengers, from the consequences of an incident, and possibly a claim. A recent proposal document from an insurance company offering insurance to steam locomotive owners, under 'Public Liability' read;
"It is strongly recommended that Spark Arresters are fitted to chimneys".

Since the majority of designs used in our hobby date from a time when such a fitment was not considered necessary, some basic redesign in the smokebox may be required to fit a spark arrester.

However, if you are in the process of building a new locomotive, it is very sensible and strongly recommended that you design and fit an effective spark arrester before putting it all together.

It seems the worst locomotives for spark throwing, are short boilered locomotives (often worked hard), which have little resistance to gas flow in the short fire tubes. As the gas speed tends to be high, this readily lifts grit and ash from the fire, especially if it is on the thin side. A tall and narrow chimney can further accelerate the exhaust, which thrown well clear of the chimney - still glowing - may then land on passengers.

This page is designed to encourage discussion and experimentation, which will allow designs to be recommended, to help eliminate this problem.

The basis of most spark arrester designs is to use gauze to strain the exhaust gases, retaining burning cinders and large grit within the smokebox; in most designs leaving the steam way unaffected.

Building a spark arrester is not complicated, and does need not need precision engineering; but it is important to ensure it can be removed easily for cleaning, and to allow cleaning access to the smokebox and tubes.

What is critical when fitting a spark arrester to a locomotive, is to ensure that as far as possible, the performance of the locomotive is not compromised.

It is probably true is that the bigger the smokebox to which the spark arrester is being fitted, the easier it will be to get your hands in to fit it. Sadly, retrofitting a spark arrester to a completed locomotive, or fitting to a 3 1/2 in gauge, or other small locomotive could be quite a challenge due to the limited size of the smokebox.

The material that seems to be most common for spark arresters is stainless (or brass) mesh with around 16 holes per square inch, and the majority of the suggestions on the following pages are based on this.

Your feedback from actual practice is welcome, and this section will be updated to act as a useful guide to the benefit of other builders of steam engines.

Please select the next page of this article for consideration of spark arresters.