Racor's New Crankcase Ventilation System
With growing industry-wide interest - and in some cases requirements - for closed crankcases on diesel and gaseous-fueled engines, the Racor
Division of Parker Hannifin Corp., Modesto, Calif., has introduced a new generation of patented crankcase ventilation systems.
New is the CCV Systems closed crankcase
ventilation filter system, designed, Racor said, to provide oil coalescence and crankcase pressure control in a variety of operating conditions. The CCV4500 is designed for
crankcase flow rates up to 10 cfm, which covers engines up to about 600 hp. The CCV600 is designed for flow rates of up to 20 cfm while the CCV8000 is designed for for flow rates up to 40 cfm.
Environmental awareness of crankcase emissions has increased significantly in recent years. As engine emissions are reduced worldwide, crankcase blow-by
vented to the atmosphere has become a more significant portion of total emissions. Thus it is becoming necessary, in more and more applications, to close
the crankcase breather system and rout the gases into the air intake system.
Unfiltered crankcase blow-by, especially in closed engine environments, like
generator set enclosures or marine engine rooms, can also cause damage to surrounding equipment, such as electronic control panels. Oil mist can also coat
aftercoolers, reducing cooling capacity, or clog air filters in the intake system, potentially damaging turbocharger components, Racor said.
"Around the world everyone is anticipating that as part of future emissions regulations, we will have to close the crankcase," a Racor spokesman said.
According to Racor, the interest in closed crankcases is being driven both by regulatory as well as operating concerns. As of Jan. 1, 1998, the U.S
Environmental Protection Agency (EPA) required that all gaseous-fueled on-highway engines must have a closed crankcase.
On the diesel side, while there are as yet no specific regulations on closing the crankcase, the overall drive to lower overall emissions has made most engine and
equipment manufacturers, as well as the users of engine-powered equipment, more interested in finding ways to close their crankcases.
Crankcase ventilation systems first found wide acceptance in the marine diesel market, especially on pleasure boats. The Federal Water Pollution Control Act
prohibits the discharge of oil or oily waste into the water. Vented crankcase blow-by can find its way into the bilge and thus into the water, potentially putting a boat into non-compliance.
While marine was among the first markets to embrace this technology, power generation systems are currently the largest single market for crankcase
ventilation systems. However, the 1998 EPA gaseous engine regulations, which mostly impact transit buses at this point, is the first step of what many feel will be
a much larger market for these systems among mobile equipment - on-highway, as well as off-highway.
Racor noted that pressure to close the crankcase is also coming from equipment
users as well, especially truck operators, who are experiencing more leakage from crankcase draft tubes, caused, at least in part, by additional amounts of oil
carryover from the new generation fuel systems in the on-highway market.
The Racor CCV4500 is now standard on all Cummins and Detroit Diesel
gaseous-fueled highway engines and will be available on Cummins' new Signature 600 series on-highway diesel.
One of the key features of the new CCV Systems is size. Racor has developed a
compact package, a must in today ís increasingly cluttered engine envelopes, apparently without sacrificing capacity or performance. For example, the CCV4500
has a diameter of 5.63 in., a height of 8.42 in., and weighs 3.5 lb. It requires 4 in. (10.2 cm) of clearance for filter removal. Inlet and outlet size is 1-3/16 STOR.
The filter housing has a die cast head, with glass-filled nylon components and black powder epoxy coating, while the filter media is a depth-loading, micro-glass coalescing type.
In operation, crankcase emissions flowing out of the engine breather are directed into the inlet of the CCV System and through a patented crankcase pressure
regulator that is integral to the head assembly. The regulator has an integral bypass valve that minimizes variation in crankcase pressure. Racor said excessive
variations in crankcase pressure can damage seals and cause a loss of oil. The regulator is located upstream of the filter element so that the pressure remains constant as the filter becomes restricted.
The regulator valve in the head assembly has two springs which hold the valve in a static open position. Under dynamic conditions, the upper spring force also
determines the maximum crankcase pressure allowed before bypass occurs.
The lower spring force maintains constant crankcase pressure under changing
inlet restrictions and crankcase flows. As negative pressure from the intake restriction is applied to the outlet of the CCV, the diaphragm valve is pulled
down. This downward movement of the valve under intake restriction, allows the valve to limit the maximum amount of vacuum that can be applied to the
crankcase, Racor said. Conversely, as crankcase pressure increases, the valve moves away from the seat, allowing more crankcase gas to flow through the filter.
When the filter becomes severely restricted through time in service, the crankcase pressure will increased to a predetermined level, causing the diaphragm
valve to move upward into bypass position, which limits the maximum crankcase pressure that can be generated.
The CCV has a "pop-up" style indicator in the top cover that alerts the user when the unit is operating in a bypass mode and the filter element must be replaced.
The gases flow in the inside-out direction through the filter, out of the unit, and into the engine intake system, usually between the air filter and the turbocharger.
Oil mist removed from the emissions flows down to the sump area of the filter housing. A drain in the sump allows the collected oil to be returned to the engine
crankcase. A check valve at the connection to the crankcase prevents gas flow or oil from bypassing the filter through the drain line.
In operation, crankcase emissions flowing out of the engine breather are directed into the inlet of the CCV and through a patented crankcase pressure regulator
that is integral to the head assembly, and has an integral bypass valve that minimizes variation in crankcase pressure. Racor said excessive variations in
crankcase pressure can damage seals and cause a loss of oil. The regulator is located upstream of the filter element so that the pressure remains constant as the filter becomes restricted.