In response to a question about the use and purpose of the Fog Pressure Units that were deployed by the Chicago Fire Department in the early 1960s, Bill Post has provided the following historical commentary;

The purpose of the Fog Pressure was to be able to get an effective stream of water on the fire quickly before a conventional engine company could get hooked up to a hydrant and led out with a canvas line. They were also handy on expressways and in tight access areas such as alleys, near railroad embankments, and in areas with poor hydrant coverage and water supply problems.

When the Fog Pressure Units were purchased and put in service between 1961 and 1966, the Chicago Fire Department had only about 11 or 12 engine companies which had booster tanks. The CFD had gone literally for ten years (1955 to 1966) without purchasing any new engines. Only the last batch of engines that had been purchased which were ten 1956 B (cab model) pumpers were equipped with 200-gallon booster tanks. One or two older model engines had been modified by the shops and had similar booster tanks added, but they were exceptions to the rule.

The Fog Pressure Units were equipped with 300-gallon water tanks and two booster reels of narrow diameter hose. They had special fog (gun style) nozzles that produced fine misty streams of water at high pressures. This is why it was called “Fog”. ¬†With the exception of the first unit which was built on a “Willys” Jeep chassis with a John Bean pump, all of the other Fog Pressure Units were built on International Harvester chassis with Darley pumps and bodies.

While a few of the Fog Pressure Units were located near some expressways, most of them were located in your busy high fire volume districts on the west and south sides. Fog Pressure 2 was located at O’Hare Field using the original Willy’s Jeep apparatus.

Fog Pressure Units were also assigned as the second pieces to all three of our Snorkel Squad companies as they allowed the Snorkel Squad men some tactical flexibility. These were also used to carry additional men and equipment. In 1964/65, the CFD had purchased three Fog Pressure Units that had longer bodies than the previous Fog Pressure rigs. These were specifically for the use of the Snorkel Squad companies.

When the fire department started getting new engines put into service in 1967, most of which were equipped with 500-gallon booster tanks, the CFD started relocating some of the Fog Pressure Units away from stations that were getting the new engines assigned to them. They also started taking them out of service so that by 1970 all of the Fog Pressure companies were gone with two exceptions. Fog Pressure 2 remained at O’Hare Field and of course they kept the Fog Pressure (SS1A) which was assigned to Snorkel Squad 1. Most of the Fog Pressure units were taken out of service in 1968 and 1969 which includes the ones that were assigned to Snorkel Squads 2 and 3 as both of those companies were decommissioned in 1969 as well.

As described in the previous post, Fog Pressure 31A was temporarily put in service at Truck 31’s new house (at the time) for a little over a year as a stop gap measure until Engine 64 was relocated into the house.

At their height in 1966 and 1967, we had twelve Fog Pressure companies in service (not including the three assigned to the Snorkel Squads) but within 2 years nearly all of them were out of service with the above mentioned exceptions.

Bill Post

Tags: , , , , ,