It’s 2014, and the EPA Tier 4-Final engines and machines are in sight. We’ve worked through all the Tiers, discussed the merits of SCR, EGR and CEGR, subtracted sulfur and blended Bio, adjusted our idle times, added some new filters, and reconfigured the heavy iron to bring emissions to almost negligible levels.
Now, let’s give some attention to the fluids supporting these new engines.
The one constant during all the emission-compliance changes to diesel-powered heavy equipment is fluids. Be they sticky, watery, oily, synthetic, pressurized, misted, carbon-based, or derived from some essence not found in nature, a machine’s fluids and a fleet’s fluid-maintenance procedures keep operations running. How you handle and maintain your Tier 4 fluids will determine your fleet’s condition and warranties.
Tier 4 Fluids as Condition Monitors
Consider thinking of your vehicle’s oil circuit as a closed-loop inner engine monitoring system. Fresh oil is manufactured to industry regulatory agency specs, so the oil is like a blank canvas before it pumps through the engine. Unlike sensors positioned to alert engine performance issues, the clean oil has full access to the systems it supports. As the engine runs, the oil constantly interacts with the inner component surfaces and responds to conditions in each cycle—a sort of fluid sensor. A fluid analysis report designed to read wear debris levels, particle counts and types, and chemical contamination can bring attention to the cause of a future failure well before the machine shows the effect. And, the beautiful part of using your fluid’s condition data as a part of your condition-based maintenance program is that every time you change out the vehicle’s fluid you create a fresh ‘sensor.’
As the Tier engines evolved, engineers tightened component tolerances to harness the power diesel combustion creates. Minute particles that previously pushed through an engine didn’t meet much resistance and eventually exited in the exhaust. Cleaner burning fuel, sophisticated filters, and exhaust-scrubbing agents eliminate pollutants and debris once found, but that is an after-the-fact fix. By then, corrosion, wear and clogs have had an opportunity to infect the engine. The better solution is to keep the contaminants out of the fluids and out of the machine. Good handling and storage practices go a long way in the fluids vs. contaminants fight.
Perhaps nothing says ‘Tier 4’ better than DEF, or diesel exhaust fluid. Engines that use Selective Catalytic Reduction (SCR) technology to produce clean exhaust require DEF.
DEF is a mix of 67.5 percent de-ionized water and 32.5 percent highly pure synthetic urea (not the farm fertilizer type) that bonds to then converts the nitrogen oxide pollutants (NOx) that are created during engine combustion into simple nitrogen and water. But even small concentrations of trace elements that are harmless in other fluids can contaminate an entire tank of DEF and throw off the chemical reactions required to change NOx to water vapor. Purity is vital.
If the required chemical interactions do not occur or the catalyst’s baffles are compromised, the SCR system will malfunction and cause the engine to shut down. Depending on how the OEM has designed the machine, it can remain locked out until the dealer physically resets the system.
Preserving DEF purity during the construction-equipment distribution cycle is a challenge. Unlike the on-road diesel industry, machines that work in the off-road construction industry don’t have the advantage of an established, robust DEF distribution network. Trucks can pull up to a DEF dispensing pump, draw off some clean DEF, and be down the road. Off-road machines are more apt to fill their DEF tanks from repackaged supplies that have gone from larger storage drums to smaller containers, carried by a service truck to the job site, then poured into the on-board tank. Multiple repackaging and field fillings create more opportunities for contamination from dirt, regular tap water, oils and dusts.
To control DEF contamination, it is imperative that DEF tanks and dispensing equipment be segregated from any equipment that is not exclusively used for DEF. In fact, DEF should be handled in the same way a medical professional handles sterilized equipment, according to Luke Van Wyk, general manager with LDJ Manufacturing, which makes Thunder Creek service trailers.
Do not use containers that may have been used for other materials, even if they have been cleaned. Detergent residue, oils and contaminants in tap water will foul the DEF.
Air can cause DEF to form crystals. Keep small containers tightly closed.
If dispensing from a 55-gallon drum or a 275- or 330-gallon IBC tote (Intermediate Bulk Container), use a coupler designed to limit air exposure and maintain purity.
Storage temperatures affect DEF shelf life, as does the stability of the storage temperature. DEF begins to freeze at 12F and degrades at 86F.
Use corrosion-resistant containers, hoses and couplings. Check the cleanliness inside the hoses regularly.
Do not use tap water to top-off or stretch DEF. Tap water contains many contaminants and will also alter the deionization properties of the DEF water.
Although DEF is nontoxic and not hazardous, it is corrosive. Corrosion usually leads to particles, so the ISO standard does not recommend these materials be used with DEF:
- Copper, copper alloys
- Zinc
- Lead
- Chromium
- Nickel
- Aluminum, aluminum alloys
- Metal-coated plastics
- Solder containing lead, silver, zinc or copper
- Sodium
- Potassium
- Biuret
- Calcium
- Magnesium
Fuel fungus
According to Fa-st Oil Filtration, an oil analysis lab and fluid testing supply distributor, there are more than 20 species of fuel bugs that can contaminate a fuel storage tank, the most common a fungus named Cladisporium Resinae. These bugs and their bacteria, yeast and mold cohorts grow when water collects as water vapor and condenses on cool metal tank walls; they feed on the fuel at the fuel/water interface. How clean the fuel blend isn’t much of a factor in the life of these contaminants, though bio-fuels seem to offer nicer neighborhoods. One single spore can produce a quarter million descendents in six hours. Their life span is a short 48 hours, but as the old microbes die off, their remains accumulate and form a slime that floats on top of the diesel fuel.
If the bug slime is pumped into the machine’s fuel system, filters clog, fuel lines narrow, and because the slime reacts with the metal tank walls to produce corrosive hydrogen sulphide, metal particles join the flow.
Contamination is too easy. After ULSD fuel leaves the manufacturing plant, all bets are off and regulations don’t count. Each transfer point is an opportunity for contamination from dust particles and water. Ideally, fuel distributors and transporters maintain clean operations, but they are under no obligation to do so. How you handle your fuel is your most effective form of contamination control.
Always have bulk fuel deliveries sampled and tested before it is pumped into your storage tanks.
Add filtration equipment or upgrade current filters. If you notice the fuel dispenser is slow, replace the dispenser filter. You will never regret just one more filtering.
Check for water before and after the fuel delivery: in the tank, around the access points, snowmelt, condensation in transfer lines, and standing water that might drain underground toward a leak in the tank. Water feeds contaminants.
The storage tank needs some time to settle after filling to allow any suspended water to separate out. In general, the warmer the fuel the more water it can hold. Test again several hours after delivery.
Work with your fuel supplier to develop a regularly scheduled program to catch and treat microbe waste with an EPA-approved biocide.
Fuel that sits for more than 90 days begins to degrade, spurring chemical changes and reactions. If your fleet does not rapidly consume stored fuel, plan for additional testings to control contaminate introduction.
Performing your own onsite fuel testing can be done with handheld test equipment and even litmus paper-type strips. Your readings may not be as precise as independent lab reports, but they can alert you to new life forms in your tank.
Some fleets have installed filtering systems that clean and double clean all the ULSD fuel delivered to their tanks. Although that option isn’t workable for every company, the philosophy is right on target.
Hydraulic fluids
Hydraulic oil manufacturers aren’t subject to spec standards like those required for oil and fuel producers. Hydraulic fluids are developed to meet performance specifications according to the equipment’s load demand, operating conditions, and pump type. (Most OEMs will provide recommendations for their equipment.) To measure quality, most manufactures point to their product’s cleanliness, using the ISO cleanliness chart for comparison. The reasons to maintain contaminant-free hydraulic fluid in Tier 4 equipment again have to do with the precise tolerances that are part of the zero-emissions engine design. Dramatically increased hydraulic pressure is a key part of power design in Tier 4 machines. Those pressures not only provide power, but they also magnify the contaminating effects of water, dirt and air in the system. Some tips:
Hydraulic fluid stored in bulk tanks should be filtered before it is stored and again as it is dispensed.
Be sure that while assembling or disassembling hydraulic system components, all the parts are kept clean and dry. This is especially important for cylinder and valve seals where friction can introduce dirt and water particles.
Air contamination causes hydraulic fluid to degrade and reduce its viscosity, leading to surface wear. Hydraulic oil can contain up to 12 percent dissolved air by volume, so check loose intake line fittings, keep the oil reservoir at factory recommended levels, and keep operating temperatures in check to prevent seal failure.
Oil contamination
CJ-4 low-ash oil is blended to meet the EPA emission specs. It is an efficient transport service for contaminants, and an excellent collection medium for particles and debris. Dirt sucked into an air intake, metal bits from friction points, and water from condensation are common incoming contaminants. High temperatures, exposure to gasses, and chemical reactions produce particles that age the oil. Left to cycle through the system, these homegrown contaminates can change the oil’s performance properties such as viscosity, or become the catalyst for gum and scale growth.
Oil contamination can be managed these ways:
Regular and frequent oil analysis reports. Short of tearing down the vehicle, the only way of determining where contaminants are starting or ending is to look at the evidence of damage carried in the used oil.
Stick with one brand if possible. That will ensure the additives and chemical compositions are near-identical from fill to fill, and give you a good benchmark when reading the oil analysis reports.
Analyze oil filters. They can provide data that point to contaminant variables such as operator work habits and technician servicing procedures.
