Ward Diesel NO SMOKE Filter
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The intent of these specifications is to define a device, system, method, etc. (hereafter referred to as "system") that will contain (extract) the toxic particulate (soot) being emitted from internal combustion engines and meet all applicable federal, state, and local standards. Apparatus-mounted does not require more than one system to fully protect your firefighters. For example, hanging hoses require firefighters to inhale the toxic particulate in hooking up the hose.


The system shall remove all visible smoke from the exhaust for an adjustable time period of 10 to 99 seconds after the vehicle starts. This is to provide ample time to start the vehicle and move away from the building. The time of filter operation shall be easily set by a mechanic or service person with common tools.

The system shall also remove all visible smoke from the exhaust whenever the vehicle is in reverse gear. After the vehicle's transmission is shifted out of reverse gear the system will continue in the filter mode for the pre-set time period. This will provide ample time to back the vehicle into the building and shut it off.

The system shall be completely automatic, not requiring action by any personnel at any time, with the exception of "normal maintenance." However, a manual override option is available to allow operation for service or special purposes.

Normal functioning of the system is in no way detrimental to the operation of the vehicle. Further, the system shall protect the engine by automatically preventing itself from activating when back pressure exceeds 1.8 PSI. At 1.5 PSI an indicator light on the cab dash shows that the filter requires changing. An operator or mechanic can quickly and easily remove the used filter and exchange it with a replacement filter.


The system shall consist of a filter, a diverter unit and an electronic control module, all of which are completely self-contained on the vehicle. Therefore the system may be operated at any time, regardless of the vehicle's location.

The filter shall be made of a porous ceramic material measuring 11.25 inches in diameter and 14 inches long, designed and manufactured specifically to filter soot from diesel exhaust for a minimum of 30 filter operating hours. The filter is encased in stainless steel with a high-temperature cushioning material between the ceramic and stainless steel. The filter is installed using four tie rods with hex nuts so that it can be removed with no special tools.

The ceramic filter shall be capable of being regenerated indefinitely by the equipment provider at a nominal cost, assuming that no physical damage to the filter is incurred. All filters are shipped in special containers provided by the system supplier.

The diverter unit shall be installed in the existing exhaust pipe and shall direct the engine exhaust either through the filter element or through the muffler. The diverter is operated by a double acting air cylinder controlled by an electrically activated, four-way, single solenoid valve.

The electronic control module, which drives the diverter unit, features a circuit board housed in a small (5" x 6" x 8") metal enclosure. This is conveniently mounted for access. The circuit board holds the timer control where the duration of the filter cycle is set. The board also features a series of LED lights that monitor each function of the system. An hour meter mounted in the electronic control module is designed to be used as a guide to determine when a filter is nearing replacement. (See Estimating Filter Life).

System installation shall be completed and tested at the customer's location, or the provider's location as determined in the original purchase order agreement. Additionally, the provider will explain the operation and maintenance of the system to the personnel who will be responsible for routine maintenance.

A written warranty will be provided to ensure that the system is free from defects in materials and workmanship for a period of one (1) year from the date of installation.


There are many variables to be considered when estimating how long a filter will last before requiring regeneration. These include:

  • Number of times the system is activated
  • Timer setting
  • Design, age and condition of engine
  • Operator starting and driving practices
  • Injector timing
  • Chemical content of the fuel

  • For example, a modern heavy duty 2-cycle engine in reasonably good condition would require the filter be changed after about 30 hours of filter use. For a 4-cycle engine, everything else being equal, 60 hours could be expected. For a small diesel Suburban type vehicle, you could expect 60 hours. Example of how to estimate the number of cycles before needing regeneration: If a 2-cycle engine has the filter timer set at 45 seconds, the filter life, based on 30 hours capacity, equals about 2,400 filter operations. (30 hrs. = 108,000 seconds. Dividing this by 45-second filter cycle equals 2,400). A 4-cycle engine under the same conditions should yield 4,800 cycles. Of course the number of cycles will depend on the variables of each vehicle.


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