A Look at Diesel Engines for Fire Apparatus
Chief Gratz evaluates points often raised by critics, discusses costs, operating expense and performance
Editor’s note: This article is from a talk Chief Gratz gave before the combined Power Plant and Transportation meeting of the Society of Mechanical Engineers in Chicago. His assignment in a panel discussion was to identify some of the facts a fire chief must consider when buying apparatus and to comment on his own experience with diesel engines.
To the fire chiefs there are four major areas which must be considered when purchasing engines for new apparatus or as replacements for repowering.
The initial purchase price of fire apparatus has increased substantially during the last few years. At the same time, the fire chief has found it more difficult to obtain funds to operate his department. These are two important factors which directly influence the type of apparatus purchased.
Until recently, many departments have been unable to consider the purchase of diesel engines because of a higher cost of several hundred dollars. However, more and more departments are now specifying higher performance, large displacement, gasoline engines, and the difference in cost has been greatly narrowed. In fact, it is not at all unusual to find that a comparable diesel can be purchased at no additional charge.
Operating costs must also be evaluated. For many years there have been those who argued that relatively low mileage made operating costs unimportant to a fire department. They cited figures indicating that fire apparatus traveled only 200 to 300 miles a year, and therefore the economy offered in a diesel engine was not significant. In too many cases, the mileage figure quoted was only response mileage and failed to consider the increasing amount of mileage accumulated during inspections and training.
A specific example can be found in one of our aerial ladders, which was repowered a year ago. With a large gasoline engine, costs were 12½ cents per mile. With the new diesel engine, fuel costs have been lowered to 3½ cents, or a savings of 9 cents per mile. This apparatus travels approximately 2,500 miles a year, which results in an annua] savings of $235. Extend this over a 20-year life, and you can see that this unit will be able to operate for about $5,000 less than with the gasoline engine.
In another station, we have two pumpers of identical size and manufacture, one with a gasoline engine and the other with a diesel. The diesel unit is operating at 8 cents per mile cheaper, resulting in an annual fuel savings of approximately $250.
These figures are based on road miles. A more realistic basis would be on engine miles or engine hours, due to the large amount of idle and operational time. Regardless, substantial savings in fuel costs are possible with a diesel engine. Another cost factor to be considered is maintenance. To date our experience shows that less preventive maintenance, time and materials have been required, thereby reducing operating costs even more.
Road and operational performance are of utmost importance to the fire service. Fire apparatus must provide quick starting, high performance acceleration and reserve power for extended pumping operations. Indications are that the diesel engine will meet all these demands and in many instances will outperform the gasoline engine. This is particularly true of road performance. Our experience has shown that even the smaller displacement diesel engine provides better performance.
Some may argue that acceptance by operating personnel is a moot point, as firemen will have to use the apparatus provided. The fact remains, however, that in many volunteer departments the membership has a voice in purchasing apparatus. In addition, both paid men and volunteers will operate more efficiently with apparatus they like. Unfortunately there are a number of misconceptions regarding diesels which are held by many people.
Objections and rebuttals
Diesels are dirty and leave a bad odor in the station.
Our experience does not indicate any excessive odor or smoke. Most of these problems can be traced to a poor grade of fuel and improper adjustments in the fuel systems. Commercial deodorizers for diesel fuel are also available.
Diesels are hard to start.
We find that diesels start faster than large gasoline engines. Ether injectors were installed to assist in starting but as yet have never been used. Larger batteries are required, but this is not a major problem.
Diesels are complicated and difficult to maintain.
Mechanics have had no problems in adjusting to service requirements of the diesel engine. Many feel that it is easier. One mechanic stated that nothing could be more difficult than properly adjusting a dual ignition-dual carburetor gasoline engine.
Diesels tend to overheat after prolonged periods of idling.
While this may generally be true, fire apparatus is normally equipped with larger radiators and auxiliary cooling valves to eliminate any such problems.
Importance of the future
A fire official must be concerned with long-range research and development. Fire apparatus will be kept in service for many years and we can’t afford to purchase items which may become obsolete. I do not suggest that gasoline engines are obsolete, but in following trade journals, one receives the impression that a major share of the research and development is being spent on diesels.
In conclusion, there can be no question that the diesel is gaining widespread acceptance throughout the fire service. This does not necessarily mean that the diesel is the solution for every department. Undoubtedly there are some departments in rural areas which coidd be faced with fueling and service problems. In urbanized areas, however, this should not present any serious difficulty.
We must also consider that experience with diesels in fire apparatus is pretty limited. Perhaps time will point out problems which, as yet, are not evident. Until such time arrives, we are one department which will continue the transition to diesel engines.