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Expert's Corner

• Load Banking
• Sound Attenuation
• Engine Oil Analysis
• Coolant Analysis
• Fuel Cell

• Diesel Fuel Reconditioning / Polishing
• Exhaust Silencers
• Diesel Fuel Analysis
• Remote Monitoring & Control

Load Banking

Wet-Stacking is a common problem with diesel engines that are operated for extended periods with light or no loads applied. When a diesel engine operates without sufficient load it will not operate at its optimum temperature. This allows unburned fuel to accumulate in the exhaust system, which can foul the fuel injectors, engine valves and exhaust system, including turbochargers, and reduce operating performance.

While typically associated with diesel engines, especially those with turbochargers, Wet Stacking also occurs in generator engines that operate on Natural Gas and Liquid Propane. Operating gaseous engines for extended periods with light or no loads applied will cause cylinder glazing. The glazed cylinder wall causes rings to "skate" on the highly polished finish and discourages the minute amount of wear which is necessary to mate piston rings with the bore. This condition will let crankcase oil pass by the piston rings and cause carbonization in the combustion chamber. This condition can damage valves, pistons, and lower the efficiency and power of your engine.

Providing additional load from the building load may not be practical with critical computer, life safety or communication equipment. Any interruption of power to these loads may cause a loss of data, operations or jeopardize personal safety. In order for an engine to operate at peak efficiency it must be able to provide fuel and air in the proper ratio and at a high enough engine temperature for the engine to completely burn all of the fuel. The proper load can be achieved by adding additional building load or by providing supplemental load through the use of a resistive load bank. These can be small portable load banks designed to be rolled up to the generator under test or they may be larger trailer mounted load banks for generator sets in the 1-3 MW range.

Generator needs to run under full load for several hours to get the engine and exhaust system back in shape.

When the exhaust stack smoke is nearly invisible, the system is cleaned of the excess oil, fuel, and hydro carbons build up. Note how the smoke clears over time.

Diesel Fuel Reconditioning (Fuel Polishing)

Fuel studies have shown that diesel fuel starts to deteriorate and form solids within 60-90 days after refining. As this change occurs, naturally accumulating particulates increase in size & mass. Heavy deposits are soon to be found in filtration equipment and sludge forms in tanks & other fuel system components. This sludge or "algae" is the most common cause of clogged filters, loss in engine rpm, excessive exhaust smoke, and damaged fuel injectors.

Additionally, in highly humid environments, water condensates inside fuel tanks wherever there is open space. Correspondingly, it is highly advised that tanks be maintained at full levels. Fuel reconditioning (fuel polishing) systems utilizing multi-stage filtration enable sludge and water to be removed from fuel tank. Additionally, fuel additives work in conjunction with filters and separators to ensure that fuel is free of particulates, sediments and water. The net result of active fuel management is clean tanks, enhanced combustion, elimination of carbon deposits, reduction in harmful emissions, and lower fuel consumption.

Sound Attenuation

Noise pollution has become a serious issue and is a concern for residential, commercial and industrial environments. Government regulatory bodies are concerned about the amount of noise emitted for overall health reasons and for short and long term protection of hearing ability. OSHA is very specific about the noise level the human ear can tolerate over time.

Hours	dBA
8	90
6	92
4	95
1	100

In addition to federal control, local ordinances establish a tolerable or safe sound level in dBA at a specific distance from the source or at the perimeter of an individual property where the sound source originates. Measuring techniques are almost always in a straight line from the source at a specific distance, and the standard distance used for most equipment is 1, 3 and 7 meters.

Sound levels from typical sources are as follows:

dBA	Source		dBA	Source
140	Engine exhaust – no muffler @ 3 ft		70	Inside a luxury car @ 60 mph
130	50 HP siren @ 100 ft		60	Large store or office
120	Jet takoff @200 ft		50	Average residence
110	Riveting machine		40	Soft whisper
100	Large diesel engine @10 ft		30	Quiet office on a Saturday
90	Train @ 20 ft		20	Mouse walking on hardwood floor
80	Inside a sports car @ 60 mph		0 - 10	Threshold of normal hearing

A diesel powered generator of 100 KW with a standard (i.e., not sound attenuated) enclosure will typically have dBA rating in the range of 78-82 at 7 meters. Varying levels of sound attenuation can be achieved through the addition of sound insulating materials, baffles and exhaust silencers at additional costs as follows:

Enclosure	dBA Range	Cost
Standard ( no attenuation)	78 - 82	$3,600 - $3,850
Level I Attenuation	74 - 76	$5,000 - $5,500
Level 2 Attenuation	64 - 66	$6,500 - $7,200

Exhaust Silencers

Sound attenuation grades (critical, hospital, etc.) for exhaust silencers are not regulated by any industry standard. As a result, one manufacturer's "hospital grade" performance may vary substantially from another manufacturer's "hospital grade". Also consider that most silencers are designed to target specific noise frequency bands so, while one silencer (reactive-type) may be better at reducing low frequency noises, another design (absorptive-type) may have better performance with high frequency noise issues. If your application requires specific noise reduction at specific frequency bands (i.e.: 35db minimum reduction at frequencies between 500hz and 2000hz), avoid relying on the silencer's performance, as shown on a data sheet that covers various silencer sizes. It may not reflect actual performance with your specific engine. Instead, focus on specific calculated silencer performance across noise frequency bands based on your engine's specific raw noise data.

Engine Oil Analysis

Comprehensive laboratory oil analysis provides maintenance professionals with an invaluable tool for decreasing overall maintenance costs, extending equipment life, and decreasing downtime. Standard test reports provide valuable information on the corrosion, contaminant and physical properties of lubricants. Analyses also provide specific recommendations on maintenance actions required based on the overall sample conditions. Recommendations are derived from a vast database of information garnered from over extensive analytical experience in lubricant analysis, as well as data provided by all major original equipment suppliers and major oil companies, including their latest specifications.

The standard Preventative Maintenance test package includes the following:

• Spectrochemical Analysis (20 elements for wear metals, additives and contaminants)
• Viscosity @100OC
• Fuel Dilution
• Fuel Soot
• Glycol

Diesel Fuel Analysis

Diesel fuel testing is designed to detect storage integrity and classify product by ASTM and industry specifications. The basic diesel fuel test package helps determine whether the analyzed fuel meets standard ASTM D/F #2 Specification. A long-term storage analysis helps predict remaining service life and product cleanliness of the diesel fuel as well as determining the fuel specifications.

	Warm Weather Analysis	Cold Weather Analysis	Long-Term Analysis
API Gravity	X		X
Cetane Index	X		X
Distillation	X		X
Sulfur	X		X
Bottom Sediment & Water	X		X
Cold Filter Plugging Point		X
Cloud Point		X	X
Pour Point		X
Particulate Contamination			X
Color			X
Microbial Growth			X
Flash Point (PMCC)			X
Accelerated Stability with Response Test *			X
* - Inhibitor Test is optional (sample of Fuel Additive is required if requested)

Testing services can be customized to troubleshoot specific applications and documentation needs. The basic fuel package requires a minimum of 16 ounces of fluid for testing. A one-quart sample is recommended for samples submitted for long-term storage testing.

Coolant Analysis

Over half of all engine failures are due to a problem in the cooling system.

Coolant Analysis takes the guess work out of properly maintaining a cooling system and can identify maintenance problems before catastrophic engine failure occurs. Regular coolant testing and routine maintenance can help achieve maximum system efficiency and save time and money in less downtime, fewer repairs and determination of proper drain intervals.

A cooling system is subject to pitting, corrosion, cavitation, erosion and electrolysis. Although coolants are formulated to help prevent these problems from occurring, coolant analysis is the only way to determine if coolant is actually providing adequate protection.

Simply changing coolant may not solve, and rarely identifies, the cause of a cooling system problem. If not properly identified and corrected, many cooling system problems can escalate, causing even more damage to other components. A quality coolant analysis program can identify electrical ground problems, combustion gas leaks, air leaks, localized overheating, etc., saving thousands of dollars in repairs, equipment downtime, and/or replacement. Coolant analysis is more than just testing the coolant. It monitors the system’s overall health and allows users to take action before further damage or engine failure occurs.

Instrumentation such as High Pressure Liquid Chromatograph, Ion Chromatograph, Inductively Coupled Plasma Spectroscopy and wet chemistry methods are utilized for detection of coolant constituents and contaminants. Analyses are on both conventional and “extended life” organic acid inhibitor based coolants include:

	Warm Weather Analysis	Cold Weather Analysis	Long-Term Analysis
pH	X		X
Conductivity/TDS	X		X
Freezing Point	X		X
Sulfates	X		X
Silicates	X		X
Nitrites/Nitrates		X
Chlorides		X	X
Boron		X
Wear Metals			X
Color			X
Microbial Growth			X
Flash Point (PMCC)			X
Wear Metals (iron, lead, copper, aluminum)			X

Remote Monitoring & Control

While remote monitoring and control of assets has long been available through LAN, WAN and standard telecom modem connectivity, it is wireless and GPS technology that has driven the price-performance metrics to enable large scale adoption at a very reasonable cost. Today, most wireless remote monitoring systems can utilize most domestic and international cellular networks, including GSM/GPRS/EDGE and CDMA/1xRTT/EvDO. These technologies can provide unlimited monitoring and remote control for a fraction of the cost of prior generation monitoring solutions, and with no expensive, proprietary software to buy, install, or manage.

The more advanced systems feature as many as 20 digital inputs and 8 analog inputs, enabling the monitoring and reporting on numerous conditions and parameters such as fuel level, fuel consumption, battery voltage, temperature, pressure, security breach, tampering, power outage, physical location, etc. Fault conditions and other emergencies can be automatically delivered to any pagers, text capable cell phone (SMS), and email addresses.

From any Internet-connected PC or mobile device, users can access a secure, password-protected M2Web Portal to view and manage all generators, no matter how many, wherever they are in North America. Web access enables users to view system-wide alert status, update alert recipient lists, generate archived alert reports (such as generator run times) from any time period, and even remotely start and stop generators.

Fuel Cell

A fuel cell is an electrochemical energy conversion device, similar to a battery in that it provides continuous DC power, which converts the chemical energy from a fuel directly into electricity and heat. When operated directly on hydrogen, the fuel cell produces this energy with clean water as the only by-product. Unlike a battery, which is limited to the stored energy within, a fuel cell is capable of generating power as long as fuel is supplied.

In simplified terms a hydrogen fuel cell works like this: Hydrogen is sent into one side of a proton exchange membrane. The hydrogen proton travels through the membrane, while the electron enters an electrical circuit, creating a DC electrical current. On the other side of the membrane, the proton and electron are recombined and mixed with oxygen from room air, forming pure water.

Although hydrogen is the primary fuel source for fuel cells, the process of fuel reforming allows for the extraction of hydrogen from more widely available fuels such as natural gas and propane or any other hydrogen containing fuel.

In addition to the Proton Exchange Membrane Fuel Cell discussed above, there are several other types of fuel cell technologies being developed, and they are typically defined by the type of electrolyte used. Some technologies are good for base load generation (powering a large building or industrial processes) on a continuous basis. Others are better suited for smaller-scale applications where the ability to start up rapidly or respond to a changing load is required.

Fuel Cell Type	Operating Temp. (°C)	Projected Efficiency	Suitable Applications
Proton Exchange Membrane (PEMFC)	60-160	35-45%	Small Stationary, Automotive, Portable
Alkaline (AFC)	80-100	60%	Space, Automotive
Molten Carbonate (MCFC)	600-700	45-60%	Large Stationary
Phosphoric Acid (PAFC)	150-220	40-45%	Large Stationary
Solid Oxide (SOFC)	700-1000	50 -65%	Stationary, Automotive

Molten Carbonate fuel cells operate at very high temperatures (600-700°C) that allow them to use fuel directly with a simplified fuel processor. They require significant time to reach operating temperature and to respond to changes in electricity demand, and therefore are best suited for the provision of constant power in large utility applications.

Phosphoric Acid fuel cells have been field tested as early as the 1970s. These systems operate at temperatures between 150°C and 200°C. The principal use of these systems has been for mid-sized (200kW) stationary power generation applications.

Solid Oxide fuel cells operate at extremely high temperatures (700-1000°C). As a result, they can tolerate relatively impure fuels. Their relatively simple design combined with the significant time required to reach operating temperature and to respond to changes in electricity demand make them suitable for large to very large stationary power applications.