Nett - Model D-Series - Diesel Oxidation Converters
D-Series diesel oxidation catalysts are designed to extend the performance of diesel catalytic converters into the low temperature range. Zeolites, also known as molecular sieves, are incorporated into D-Series catalyst washcoats. These zeolites trap and store diesel exhaust hydrocarbons during periods of low exhaust temperature, such as during extended engine idling. Then, when the exhaust temperature increases, the hydrocarbons are released from the washcoat and oxidized on the catalyst.
Direct-Fit Catalytic Mufflers
Nett Technologies has direct-fit catalytic mufflers available for thousands of models of construction equipment, forklift trucks and other diesel powered equipment. The pre-designed models are in-stock or can be built and shipped within a few days. Catalytic mufflers are available to replace the original muffler for any diesel application. The D-Series emission control catalyst is built into the muffler and is selected based on the size of the engine. Catalytic mufflers are guaranteed to be a exact-fit replacement for the original muffler. The emissions reduction performance of catalytic mufflers is also guaranteed, provided the engine is well maintained without excessive lube oil consuption.
Universal-Fit Catalytic Converters
Nett® Technologies offers two universal-fit configurations for the D-Series catalytic purifiers, as shown in images below. The welded (one-piece) design is more compact and recommended for space-limited applications. The clamped design allows for easy removal of the center-body (catalyst) for inspection and cleaning, if required.
The D-Series catalysts are available on ceramic substrates. Round cordierite substrates with square cell geometry are used in all D-Series catalysts. Selected properties of the substrates are listed in Table 1 below.
Catalyzed substrates are wrapped in special packaging mat and packed into a steel container using the tourniquet packaging technology. Tourniquet is known as the best catalytic converter packaging technology, producing the most rugged and durable converters.
Ceramic substrates produce somewhat higher pressure drop than metallic substrates of the same dimensions, due to their thicker walls. However, for most applications the D-Series catalysts are sized larger than M-Series DOCs, in order to provide sufficient volume of the HC trap. By using D-Series catalyst substrates of larger diameter and larger frontal area, it is possible to achieve comparable pressure losses for the M-Series and D-Series catalysts when installed on identical engines.
Most pressure drop comparisons between the ceramic and metal catalyst supports are based on bare (uncoated) substrates. While the uncoated ceramic supports do have thicker walls (Table 1), the difference in wall thickness decreases after the catalyst coating is applied. This is explained by the inherent porosity of ceramic substrates, which 'soak in' a portion of the catalyst coating into the wall pores. Since metallic substrates are not porous, the entire catalyst coating stays at their surface. Therefore, when the same loading of catalyst material is applied to a ceramic and a metallic substrate, it produces a thicker coating layer and more flow restriction in the metallic support.
Several advantages of Nett® catalytic converters make them the superior choice as a generic, retrofitting converter for all diesel engine applications:
- High mechanical durability. Ceramic substrates are packaged using the tourniquet technology, which produces the most rugged and durable catalytic converters.
- Easy Maintenance. The cell densities of the catalytic monoliths are carefully selected for each application. There is very little risk of clogging by diesel particulates. Most applications are virtually maintenance-free.
- Low Pressure Drop. Due to thin walls and large frontal area the catalyst substrates have low pressure drop and do not cause any fuel penalty.