Date completed: March 1, 1996
Location: Applied Chemical Analytical Lab, Omaha, Nebraska
© 2008 Applied Chemical Specialties, Inc.
No-Rosion five-year coolant corrosion tests in varied duty applications
ABSTRACT:
The purpose of this test is to quantitatively determine the amount of corrosion to the six metals commonly found in light, medium, and heavy-duty vehicle applications during an actual five year coolant service interval in which No-Rosion is properly applied with standard silicate-based antifreeze/water coolant mixtures. Varied driving conditions and mileage intervals will also be used as a means of further determining the factors which influence No-Rosion rates of depletion, and at exactly what point in time/mileage during service that additional product should be added. Corrosion coupons will be weighed prior to service, and at different time/mileage intervals, as a means of determination of the exact amount of metal loss due to corrosion. The actual metal loss will then be calculated during each year of service, and this metal loss with be compared against acceptable corrosion limits as established by the ASTM in the D-2570 test, which is the closest applicable benchmark for comparative purposes.
MATERIALS:
(1) Test vehicles:
Vehicle 1 - 1989 Pontiac Lemans (gas "light duty" vehicle)
Vehicle 2 - 1990 Ford Econoline Van (gas "light duty" vehicle)
Vehicle 3 - 1988 Jeep Cherokee (gas "light duty" vehicle)
Vehicle 4 - 1989 Chevrolet C-Series Truck (diesel "medium duty" vehicle)
Vehicle 5 - International Model 4000 Truck (diesel "medium duty" vehicle)
Vehicle 6 - International Model 9200 Truck (diesel "heavy duty" vehicle)
Vehicle 7 - Kenworth Model 910 Truck (diesel "heavy duty" vehicle)
(2) Bundled corrosion coupon test specimens as described in ASTM D2570 procedure, and as
supplied by Midland Scientific Company
(3) Prestone Brand antifreeze as supplied by Champion Auto
(4) No-Rosion Coolant Additive as supplied by Applied Chemical
(5) Tap water with approximately 5 gpg hardness
(6) Specimen bundle mounts (as constructed by lab personnel)
(7) Sodium Molybdate test kit as supplied by LaMotte
(8) Sodium Nitrite test kit as supplied by LaMotte
PROCEDURE:
(1) The cooling systems of each of the seven test vehicles were initially drained of their prior coolant solutions, and thoroughly flushed by running cool tap water from the end of a hose into the opening atop the radiator. Visual inspection was used to identify exactly when all old coolant was removed, and was running clear from the cooling systems.
(2) While the cooling systems of the test vehicles were empty of coolant and out of service, the radiators of each vehicle were removed, and the side tanks were removed so as to allow corrosion coupon samples to be mounted to the inner walls of the tanks using specimen bundle mounts which were specially prepared for this procedure. Tanks were then re-soldered to the radiators by an outside service provider, and the radiators replaced into each test vehicle. In a few instances, the side walls of the radiator tanks required slight modification in order to allow the additional necessary space for the specimen coupon samples to fit inside the radiators upon re-soldering.
(3) Each of the cooling systems was refilled with standard tap water and Prestone brand antifreeze so as to facilitate a 44% antifreeze/56% mixture.
(4) No-Rosion was then added to the cooling systems of each of the test vehicles so as to facilitate an initial concentration of exactly one pint of No-Rosion per every 22 quarts of coolant capacity. This concentration was sufficient to create molybdate residuals in the 50-60 ppm range, and nitrite residuals in the range of approximately 1,600-1,800 ppm.
(5) At the completion of replacement of the radiators and coolant solutions, the test kits were used to test the coolant solutions in order to record an initial concentration of nitrite and molybdate residuals.
(6) Each test vehicle was then reentered into regular driving and service routines. The mileage of each vehicle was recorded at this point, and the date of each reentry into regular service was recorded.
(7) Each vehicle was driven for one year of regular service. Mileage was monitored on an ongoing basis, and for those vehicles being driven at particularly high mileage, a sodium molybdate and sodium nitrite test was performed after each 10,000 miles of service in order to be certain that proper No-Rosion residuals were being maintained. If additional No-Rosion was necessary to be added, the date and mileage of such addition was recorded.
(8) After the first year of service, it was discovered that a "rule of thumb" to follow regarding typical vehicle molybdate and nitrite depletion rates with No-Rosion was depletion after approximately 30,000 miles. Accordingly, after the first year of testing, the procedure was modified to reflect this discovery, and rather than nitrite and molybdate tests being performed every 10,000 miles, one additional pint of No-Rosion per every 22 quarts of coolant capacity was added every 30,000 miles to those vehicles which traveled a longer distance between annual service intervals.
(9) At the completion of each 12 month service duration, the cooling systems of the test vehicles were again drained, and the old coolant mixture NOT DISCARDED, but rather saved for reapplication. The radiators were removed at the completion of each year, the side tanks removed, and the corrosion coupon specimens were removed, weighed, and reinserted into the bundle mounts. The tanks were resoldered, the radiators put back into the respective vehicles, and the same SAVED coolant solution added back to the cooling system of each vehicle.
(10) For each vehicle which DID NOT require additional No-Rosion to be added every 30,000 miles of service, due to the fact that they were lower mileage vehicles, another application of No-Rosion was added at a rate of one pint per 22 quarts of system capacity. This was judged sufficient as recharging of the systems, and supported by nitrite and molybdate tests which were run at the completion of the first 12 month service interval.
(11) The differences between the initial weight and final weight of each of the corrosion coupons from each of the test vehicles were recorded as "corrosion loss" for the purposes of this experiment. For record keeping purposes, for each 12 month duration, the final weight of the preceding 12 month interval shall count as the initial weight of the 12 month interval being recorded.
(12) At the completion of the fifth 12 month service interval, a final tear-down of each vehicle's cooling system took place, and the experiment was completed.
(13) The corrosion loss for each of the metals tested in this experiment were compared each year to limits defined as generally acceptable by the ASTM.
RESULTS:
Regular service reentry date: 2/26/90
Vehicle 1:
Initial 12 mo. 24 mo. 36 mo. 48 mo. 60 mo.
Mileage 8,365 19,834 32,482 41,843 56,903 69,398
Wt loss
Copper -- 1 1 1 2 2
Brass -- 0 1 0 1 2
Steel -- 0 0 0 1 0
Iron -- 0 0 0 1 1
Lead -- 1 0 1 0 0
Aluminum -- 0 0 1 1 0
Vehicle 2*:
Initial 12 mo. 24 mo. 36 mo. 48 mo. 60 mo.
Mileage 3,489 41,390 77,302 112,346 138,297 181,382
Wt loss
Copper -- 1 1 2 1 2
Brass -- 0 1 1 0 3
Steel -- 0 0 1 0 1
Iron -- 1 0 0 0 0
Lead -- 0 1 1 1 1
Aluminum -- 0 0 0 1 1
Vehicle 3:
Initial 12 mo. 24 mo. 36 mo. 48 mo. 60 mo.
Mileage 23,903 38,720 51,983 67,025 72,189 89,378
Wt loss
Copper -- 2 1 1 1 2
Brass -- 0 0 1 0 1
Steel -- 0 0 1 0 1
Iron -- 0 0 0 0 0
Lead -- 0 0 0 0 0
Aluminum -- 0 0 1 1 2
Vehicle 4*:
Initial 12 mo. 24 mo. 36 mo. 48 mo. 60 mo.
Mileage 40,333 83,301 109,112 151,438 187,291 229,383
Wt loss
Copper -- 4 3 3 4 5
Brass -- 2 1 2 1 3
Steel -- 1 1 2 4 6
Iron -- 0 0 1 2 3
Lead -- 0 1 2 1 4
Aluminum -- 0 0 1 1 2
Vehicle 5*:
Initial 12 mo. 24 mo. 36 mo. 48 mo. 60 mo.
Mileage 48,390 83,903 154,373 223,888 297,009 377,498
Wt loss
Copper -- 3 3 2 4 6
Brass -- 1 1 1 2 3
Steel -- 0 0 1 1 1
Iron -- 0 0 1 0 2
Lead -- 0 0 2 0 2
Aluminum -- 0 0 1 0 1
Vehicle 6*:
Initial 12 mo. 24 mo. 36 mo. 48 mo. 60 mo.
Mileage 77,221 130,294 192,393 278,309 314,381 424,364
Wt loss
Copper -- 4 2 3 2 7
Brass -- 3 1 2 1 2
Steel -- 1 0 1 0 4
Iron -- 0 0 1 1 1
Lead -- 1 0 0 1 2
Aluminum -- 0 0 1 0 1
Vehicle 7*:
Initial 12 mo. 24 mo. 36 mo. 48 mo. 60 mo.
Mileage 18,294 72,389 138,120 204,300 267,117 352,006
Wt loss
Copper -- 3 2 3 4 3
Brass -- 2 2 1 2 1
Steel -- 0 1 1 0 3
Iron -- 0 0 0 1 1
Lead -- 0 0 1 0 0
Aluminum -- 0 0 1 0 1
* Asterisk indicates that this vehicle exceeded 30,000 miles per 12 month intervals, and accordingly an additional pint of No-Rosion per every 22 quarts cooling system capacity was added at 30,000 increments, prior to the completion of the regular 12 month routine. The absence of an asterisk indicates that No-Rosion was added once every 12 month routine.
CONCLUSION:
The final cumulative losses after 5 years of service due to corrosion for the six metals tested in the seven test vehicles were as follows:
Cumulative 5 year loss ASTM D2570 Maximum
Vehicle 1:
Copper 7 mg 20 mg
Brass 4 mg 20 mg
Steel 1 mg 20 mg
Iron 2 mg 20 mg
Lead 2 mg 60 mg
Aluminum 2 mg 60 mg
Vehicle 2:
Copper 7 mg 20 mg
Brass 5 mg 20 mg
Steel 2 mg 20 mg
Iron 1 mg 20 mg
Lead 4 mg 60 mg
Aluminum 2 mg 60 mg
Vehicle 3:
Copper 7 mg 20 mg
Brass 2 mg 20 mg
Steel 2 mg 20 mg
Iron 0 mg 20 mg
Lead 0 mg 60 mg
Aluminum 4 mg 60 mg
Vehicle 4:
Copper 19 mg 20 mg
Brass 9 mg 20 mg
Steel 14 mg 20 mg
Iron 6 mg 20 mg
Lead 8 mg 60 mg
Aluminum 4 mg 60 mg
Vehicle 5:
Copper 18 mg 20 mg
Brass 8 mg 20 mg
Steel 3 mg 20 mg
Iron 3 mg 20 mg
Lead 4 mg 60 mg
Aluminum 2 mg 60 mg
Vehicle 6:
Copper 18 mg 20 mg
Brass 9 mg 20 mg
Steel 6 mg 20 mg
Iron 3 mg 20 mg
Lead 4 mg 60 mg
Aluminum 2 mg 60 mg
Vehicle 7:
Copper 15 mg 20 mg
Brass 8 mg 20 mg
Steel 5 mg 20 mg
Iron 2 mg 20 mg
Lead 1 mg 60 mg
Aluminum 2 mg 60 mg
Because the 5 year cumulative corrosion losses for each of the 6 metals tested in this variable duty actual service routine experiment fall below ASTM D2570 acceptable maximum limits, the empirical data suggests that application of No-Rosion once every 12 months, or once every 30,000 miles (whichever comes first) should allow coolant life to be extended to 5 years. Therefore, a cooling system in which No-Rosion is being added in such a manner should safely be able to go 5 years between flushes of old coolant without exceeding ASTM D2570 maximum corrosion limits.