DOC Engine Technology Provides Cost-Effective Tier 4 Compliance

The U.S. Environmental Protection Agency (EPA) has adopted a comprehensive national program to reduce emissions from diesel engines. Implemented in a series of progressively more stringent tiers, the new standards require reductions in carbon (soot), hydrocarbons from fuel and lubricating oil, metallic particles, and watery sulphuric acid. Until this year, diesel engines have had to comply with the Tier 4 Interim standard, which specified lower emissions but did not reach the full goal. Beginning Jan. 1, 2015, the new Tier 4 Final standard requires all new diesel engines used in off-road equipment to meet substantial reductions in emissions. To meet the full Tier 4 standards, diesel pump package manufacturers are required to use engines with advanced emission controls. Tier 4 requires all diesel engines to have reductions in particulate and nitrogen oxide emissions. While previous generations of diesel engines could achieve the lower Tier 3 and Tier 4 Interim standards by managing emissions within the combustion chamber, Tier 4 Final’s more stringent standards require an after-treatment device.

In addition to these EPA standards, California and other states have either implemented or are considering additional carbon emissions that regulate the total emissions allowed for a given project. The contractor operating the equipment or holding the permit is responsible for compliance. Contractual elements sometimes require the person renting the pump package to state that the equipment is in compliance with all ordinances. This is of particular concern for companies with large fleets of diesel pump packages that move equipment from state to state. Tier 4 Final compliant pump packages have been available on the market for the past year, but most are either expensive custom solutions or have older engines to which a diesel particulate filter (DPF) has been added. DPF-configured engines rely on filters to remove soot. Their primary disadvantage is that they require regular regeneration cycles in which high heat is created to burn the accumulated particulate from the filter. These regeneration cycles require engine downtime, and they also carry a substantial risk: If the regeneration cycle is missed or delayed, the clogged filter can damage the engine, often requiring factory repair. To avoid this risk, DPF engines require substantial monitoring to ensure regeneration cycles are occurring effectively and at the proper times. Because the regeneration cycle creates a disruption in pump operation, jobs with a high volume of infiltration may require a second pump on-site to run while the first pump undergoes the regeneration cycles. A better solution for pumping involves an engine with a diesel oxidation catalyst (DOC). DOC-configured engines use a catalytic converter to promote oxidation of exhaust gas components by oxygen, which is present in diesel exhaust. When passed over the catalyst, carbon monoxide, hydrocarbons and particulates are oxidized, forming harmless products. The advantage of DOC engines is that they do not require regeneration cycles, which minimizes maintenance, downtime and risk of expensive factory repair. One manufacturer of EPA-compliant pumps has developed a Tier 4 Final pumping solution that combines a 4-, 6- or 8-inch pump and an L4 DOC engine, which has been specifically designed for Tier 4 Final compliance, minimal complexity and low installed cost. The water-cooled, four-cylinder inline engine has a simple exhaust aftertreatment. It is electrically controlled and has cooled, external exhaust gas recirculation that eliminates the need for regeneration cycles. The engine’s DOC enables maintenance-free operation under all ambient conditions.