September 28, 2009

Khesha T. Reed Manager, Heavy

- Duty and Nonroad Engine Group Compliance and Innovative Strategies Division Office of Transportation and Air Quality
U.S. Environmental Protection Agency 1200 Pennsylvania Ave. N.W. Washington, D.C. 20460

Via email and overnight mail

Re: Support for EMA’s Request for Adminstrator Approval of New Maintenance Intervals for the Refill of

Reductant Fluid Tanks Utilized With H e avy

- D uty O n

- H ighway SCR

- Based Emission Control Systems

Dear Ms. Reed,

Cummins has submitted the first of what will be several certification applications for engine families utilizing an emissions control system referred to as a Selective Catalytic Reduct ion (“SCR”)

device. T hese devices require the addition of reductant

, being referred to as Diesel Exhaust Fluid (“DEF”), into the engine exhaust to accomplish the emission reduction. Typically, the amount of DEF required to be added is about 2 to 4 % of t he fuel consumed. For Heavy

- Heavy and Medium

- Heavy Duty Diesel Engines, EPA requires that aftertreatment systems, such as SCR devices, not be required to be maintained more frequently than 100,000 miles initially and then no more frequently than 150,000 m iles

thereafter (86.094

- 25)

. C learly it is unreasonable to have such a great amount of DEF on board as to have a range of 150,000 miles.

Under section 86.094

- 25(b)(7)(ii) EPA allows manufacturers to petition for reconsideration of the

minimum maintenance interval. The Engine Manufacturers Association, of which Cummins is a member, filed such a petition on June 11, 2009. EPA has not yet acted upon EMA’s request. Cummins needs quick turn

- around of its applications for certification, and is submitting thi s letter to provide further justification and support for the shorter maintenance interval requested by EMA

.

The need for a shorter maintenance interval can be seen by providing a couple of real

- world examples. At the upper end of real world examples is a line haul truck. In the case of a line haul truck, the average fuel economy is approximately 6 mpg. Over 150,000 miles, this line haul truck would consume 150,000 miles / 6 miles/gallon

, or 25,000 gallons of diesel fuel. At a 3% average DEF consumptio n rate, this would amount to 25,000 gallons x 0.03

, or 750 gallons of DEF. Assuming a density of 9 lb / gallon, this amount of DEF would weigh 6,750 lbs. A line haul truck is allowed a maximum gross vehicle weight of 80,000 lbs. The tare, or empty, weig ht of a typical line haul truck is 35,000 lbs, leaving 45,000 lbs for cargo. The requirement to have a DEF tank capable of carry ing 750 gallons or 6

, 750 lbs of DEF would reduce the cargo

- carrying ability to 38,250 lbs, or by 15%. A new linehaul truck ty pically runs approximately 120,000 miles a year in the first few years of operation. This means that the DEF refill interval would be 1.25 years.

At the other extreme of real

- world examples , Cummins provides engines for use in ‘ chassis cabs ’

. We certify these engines as medium heavy

- duty diesel engines. If we assume that the average fuel economy of engines used in chassis cabs is 12 mpg , t hen, over 150,000 miles, a chassis cab would consume 150,000 miles / 12 miles/gallon

, or 12,500 gallons of di esel fuel. At a 3 % average DEF consumption rate, this would amount to 12,500 gallons x 0.0 3

, or 375 gallons of DEF. Once again assuming a density of 9 lb / gallon, this amount of DEF would weigh 3

, 375 lbs. A typical class 3 chassis cab has a carrying ca pacity of 5000 lbs. The requirement to carry 3,375 lbs of DEF would reduce the cargo carrying capacity to 1,625 lbs, or by 68 %. A chassis cab typically operates 20,000 miles per year. This means that the DEF refill interval would be 7.5 years.

Informat ion about these two examples are summarized on the following table.

Application Minimum

Maintenance

Interval DEF Required (gallons) DEF Required (pounds) Time Between
DEF Refills

Line Haul Truck 150,000 miles 750 6,750 1.25 year

Chassis Cab 150,000 miles 375 3,375 7.5 years

Paragraph 86.094

- 2 5 (b)(7)(ii) requires a petitioner to show that the scheduled maintenance is new, and that this new scheduled maintenance is a direct result of the implementation of new technology not found in production prior to the 1980 model year. Certainly this is the case in this situation where the new technology being employed is SCR, and the fact that SCR requires the addition of a reductant in order to perform its emission reduction purpose.

Paragraph 86.094

- 2 5 (b)(7) (ii) goes on to require a petitioner to declare whether the maintenance

is emission

- related or non

- emission

- related and if it is determined to be emission

- related whether the

maintenance critical or non

- critical. As is declared in EMA’s petition, this sch eduled maintenance is

considered to be critical emission

- related maintenance.

Finally paragraph 86.094

- 2 5 (b)(7)(ii) requires the petitioner to suggest a maintenance interval and provide evidence that this scheduled maintenance interval is the ‘ maximum fea sible maintenance

interval ’

.

Cummins would propose that two possible shorter maintenance intervals exist, each of which drive decidedly different DEF refill ing networks. The first possibility is to demand a DEF refill interval o n
t he order of magnitude of the lube oil change interval. In the case of the examples provided above, line haul trucks typically have a lube oil change interval of 30,000 miles. Chassis cabs typically go 7,500 miles between oil change intervals. If this were demanded by the Ag ency, a DEF refilling infrastructurewould need to be developed around the heavy

- duty vehicle lube oil change infrastructure. The following table provides information pertinent to this case. The same assumptions are made in calculating the se values as we re made in the above analysis of the 150,000 interval

.

Application Lube Oil Change

Interval DEF if required

to have sufficient

DEF on board to

go an oil change

interval (gallons) DEF if required

to have sufficient

DEF on board to

go an oil change

interval (pounds) Time Between
DEF Refills

Line Haul Truck 30,000 miles 150 1,350 3 months

Chassis Cab 7,500 miles 18.75 168.75 4.5 months

The second possibility is to demand a DEF refill interval on the order of magnitude of the diesel refueling interval. L ine haul trucks typically have a fuel tank range of 1620 miles. Chassis cabs typically

can go a maximum of 624 miles between fuel tank refills. If this were demanded by the Agency, a DEF refilling infrastructure would dev elop around the refueling infrastructure.

Application Max Refueling

Interval DEF if required

to have sufficient

DEF on board to

go a fuel change

interval (gallons) DEF if required

to have sufficient

DEF on board to

go a fuel change

interval (pounds) T ime Between
DEF Refills

Line Haul Truck 1620 miles 8.1 72.9 4.9 days

Chassis Cab 624 miles 1. 56 14.04 11.4 days

As pointed out above, heavy duty vehicles are purchased to do work, they move either people or goods or both . Every effort is made to reduce the tare weight to increase cargo

- carrying capacity. In addition, as the for m of the emission standards (g/bhp

- hr) shows, as heavy

- duty engines do more work, they produce more emissions. So, every effort should be made o n EPA’s part to keep heavy

- dutyvehicles as efficient as possible, and the DEF tank size practical. Even though having a DEF refill infrastructure built around the refueling interval requires more DEF refueling sites than would a DEF refilling infrastruct ure built around the lube oil change infrastructure, the increase in vehicle efficiency more than makes up for the cost of doing so.

Cummins believes that the ‘maximum feasible maintenance interval’ is that associated with the refueling interval and that the three cases enumerated in EMA’s petition (duplicated below) represent the

‘maximum feasible maintenance interval’.

... the DEF tank refill intervals for which EMA seeks the Administrator's approval (the

"Recommended DEF Re

- Fill Intervals") are, as follows:

(i) for HDOH vehicles programmed with a driver inducement strategy that derates the engine at a rate of 1% per minute up to 40%, the DEF tank refill interval must provide a range of vehicle operation that is no less than the range equal to the HD OH vehicle's fuel capacity ( i.e., as 1:1 ratio);

(ii) for all other HDOH vehicles that also have a constant DEF level indicator, the DEF tank re

- fill interval must provide a range of vehicle operation that is no less than twice the range of the
HDOH vehicle's fuel capacity ( i.e., a 2:1 ratio); and

(iii) for all other HDOH vehicles that do not have a constant DEF level indicator, the DEF tank re

fill interval must provide a range of vehicle operation that is no less than three times the range of

the H DOH vehicle's fuel c apacity ( i.e., a 3: 1 ratio).

I hope these examples help EPA see the necessity of granting EMA’s petition, and that EPA will do so expeditiously.

Sincerely,

Robert A. Jorgensen

Executive Director

– Product Environmental Ma nagement
Cummins Inc.