Selecting the Right Mobile Diesel Generator for Transloading Applications

For companies involved in mobile transloading of hazardous products such as gasoline, Jet A, ethanol, and propane/butane, the selection of a reliable and compliant mobile diesel generator is critical. This equipment ensures the safe and efficient operation of pumps, controls, and lighting systems in the field. However, choosing the right generator requires careful consideration of power loads, safety regulations, and environmental compliance. Here’s a guide to help you navigate this process and make informed decisions.

Sizing the Generator: Meeting Power Demands

The first step in selecting a mobile diesel generator is to properly size it to meet the specific power requirements of the application. Pumps and motors used in transloading typically have horsepower ratings in the 20-30 hp range, which translates to significant electrical demand. Here’s how to calculate the generator size:

1. Calculate Motor Power in kW:
   • Convert horsepower (HP) to kilowatts (kW) using the formula:
     kW=HP×0.746Efficiency×Power FactorkW = \frac{HP \times 0.746}{Efficiency \times Power\ Factor}kW=Efficiency×Power FactorHP×0.746​
   • For example, a 25 hp motor with an efficiency of 90% and a power factor of 0.85 would need around 24 kW of power.
2. Add Other Loads:
   • In addition to the motors, other electrical loads such as control systems, lighting, and auxiliary devices must be considered. Each should be listed and their wattage summed.
3. Include a Safety Margin:
   • It’s recommended to size the generator 20-30% above the calculated load to account for startup surges (inrush currents) and future scalability. So, if your total load is 30 kW, aim for a generator in the 36-40 kW range.

Compliance and Regulations

Generators used in mobile transloading must comply with several key regulations and standards to ensure both safety and environmental sustainability.

1. Tier 4 Emission Standards:
   • The EPA Tier 4 regulations are mandatory for all new non-road diesel engines, including mobile generators. Tier 4 standards significantly reduce emissions of particulate matter (PM) and nitrogen oxides (NOx), which are critical in environments where emissions control is important.
   • Be sure to select a generator that is certified as Tier 4 Final to meet these stringent standards.
2. Electrical Area Classification:
   • Transloading of hazardous materials like gasoline and propane typically takes place in classified hazardous locations. For these areas, generators must meet the requirements of Class I, Division 2 under the National Electric Code (NEC).
   • Class I, Div. 2 locations are those where flammable gases or vapors may be present under abnormal conditions, so any electrical equipment in these areas must be specifically designed and certified for such environments.
3. Other Regulatory Considerations:
   • Ensure that the generator meets local and state safety codes, including those from OSHA and NFPA, which regulate safe operation in hazardous environments.
   • If operating internationally, consider local environmental and safety standards that might vary from U.S. regulations.

Generator Specifications Checklist

For engineers tasked with specifying a mobile diesel generator for transloading applications, the following checklist can serve as a guide:

1. Power Output:
   • Minimum output calculated to meet motor loads (in kW).
   • Extra capacity for startup surges and future load expansion (20-30% above total load).
2. Engine Compliance:
   • EPA Tier 4 Final certification for emission control.
   • Ability to operate efficiently in various weather conditions.
3. Electrical Classification:
   • Rated for Class I, Div. 2 hazardous locations.
4. Operational Requirements:
   • Voltage options for different transloading sites.
   • Integrated circuit breakers for safety.
   • Ability to handle single-phase or three-phase loads based on pump specifications.
5. Physical and Mobility Features:
   • Mounted on trailers or skids for easy transport.
   • Weatherproof and explosion-proof enclosures for harsh conditions.
   • Forklift pockets or lifting lugs for quick mobilization.
6. Fuel Capacity and Efficiency:
   • Diesel fuel tank large enough to support long transloading operations without frequent refueling.
   • Fuel efficiency aligned with operating costs and environmental considerations.
7. Control and Monitoring:
   • Advanced control systems for remote monitoring and automation.
   • Built-in protections for overload, short circuits, and voltage fluctuations.
8. Additional Considerations:
   • Noise levels (ensure compliance with local noise ordinances). See additional considerations below
   • Easy access for maintenance and servicing.

Noise Levels: A Key Consideration for Mobile Generators

Noise emissions are a critical factor when selecting a mobile diesel generator, especially for transloading operations in populated or sensitive areas. Many industrial sites have strict regulations on noise pollution, and ensuring compliance can be as important as meeting emissions or safety standards.

Here’s how to address noise levels when selecting a generator:

1. Understand Local Noise Regulations:
   • Different regions have varying limits on acceptable noise levels, often measured in decibels (dB). Generators typically produce noise in the range of 65-85 dB, which can be loud enough to cause disruptions or even hearing damage if not properly managed.
   • Many municipal or industrial codes require noise levels to stay below a certain threshold, especially in residential or environmentally sensitive areas.
2. Sound Attenuated Enclosures:
   • To reduce noise, many generators come equipped with sound-attenuating enclosures. These specialized housings can significantly reduce the operational noise of a generator, sometimes bringing it down to around 60-70 dB.
   • Consider a soundproof enclosure or super-silent generator model if you will be operating near noise-sensitive locations.
3. Exhaust Mufflers:
   • High-performance mufflers can further lower noise levels by dampening exhaust sounds. These are commonly available as an option or upgrade for most mobile diesel generators.
4. Distance and Site Positioning:
   • Noise can also be reduced by placing the generator at a greater distance from work areas or by using barriers (e.g., fences, natural landscape, or specially designed noise barriers). Keep in mind that noise decreases significantly as you move away from the source.
5. Typical Acceptable Noise Levels:
   • Industrial sites: Usually allow for higher noise levels, but local guidelines still require consideration.
   • Residential or public areas: These locations may enforce strict limits, requiring generators to operate under 65 dB at 23 feet (7 meters).

Checklist Additions for Noise Control:

• Sound attenuation enclosure: Consider for areas where noise restrictions apply.
• Exhaust muffler: Specify if noise reduction is a priority.
• Noise level rating: Choose a generator with a certified dB rating that meets site-specific noise regulations.
• Site layout for noise control: Factor in the location and positioning to minimize disruption.

By including noise management as part of your generator selection process, you can ensure compliance with local regulations and maintain a safer, more comfortable environment for operators and nearby communities.

Fuel Tank Size: Ensuring Continuous Operation

When selecting a mobile diesel generator for transloading operations, fuel tank size is a crucial consideration. An appropriately sized fuel tank ensures uninterrupted operation, reduces downtime for refueling, and improves overall efficiency, especially in remote or continuous-duty applications.

Here’s how to determine the right fuel tank size for your generator.

Factors to Consider for Fuel Tank Sizing:

1. Generator Power Output and Fuel Consumption:
   • The generator’s power output (in kW) directly influences its fuel consumption. Generally, larger generators consume more fuel, so understanding the consumption rate is critical.
   • Most diesel generators provide a fuel consumption rate in gallons per hour (GPH), which varies based on load. For example, a 40 kW generator might consume around 3-4 gallons per hour at full load but less at lower loads.
2. Desired Runtime:
   • Consider how long the generator needs to run between refueling. For transloading applications, operations often need to run for extended periods. You should aim for a tank size that provides at least 8-12 hours of continuous runtime under typical load conditions.
   • To calculate the minimum fuel tank size and other considerations see below:
3. Load Factor:
   • Generators rarely run at full capacity all the time. The load factor (the percentage of the generator’s capacity being used) affects how much fuel the generator consumes. Lower load factors will extend runtime and reduce fuel consumption. It’s good practice to size the fuel tank based on the average load, not just the maximum.
4. Fuel Tank Design:
   • Generators come with integrated fuel tanks, but for extended operations, external bulk fuel tanks can be connected. These allow for significantly increased fuel storage and longer runtime without refueling.
   • Ensure the fuel tank is double-walled to meet EPA and local environmental regulations for fuel containment and spill prevention.
5. Refueling Logistics:
   • Consider how often the generator will be accessible for refueling. If the site is remote or refueling is logistically challenging, a larger tank may be necessary. Additionally, backup fuel tanks may be required for redundancy in critical operations.

Typical Fuel Tank Sizes for Mobile Generators

Here’s a guide to fuel tank sizing based on typical generator power outputs:

• 20 kW Generator:
  • Fuel Consumption: ~2 gallons/hour at full load
  • Tank Size for 12-hour Runtime: ~24 gallons
• 40 kW Generator:
  • Fuel Consumption: ~3-4 gallons/hour at full load
  • Tank Size for 12-hour Runtime: ~48 gallons
• 60 kW Generator:
  • Fuel Consumption: ~5-6 gallons/hour at full load
  • Tank Size for 12-hour Runtime: ~72 gallons

Note: Always consider adding additional capacity to account for variations in load, unexpected delays, or future operational needs.

Generator Pricing: Budgeting for a Mobile Diesel Generator

The cost of a mobile diesel generator can vary significantly based on factors such as power output, compliance with regulations (like Tier 4 emissions standards), additional features, and the manufacturer. When planning for a generator purchase, it’s essential to factor in not just the upfront cost but also long-term operational expenses, including maintenance, fuel, and potential upgrades.

Factors Influencing Generator Pricing:

1. Power Output (kW Rating):
   • Lower power generators (20-40 kW) typically cost between $15,000 and $30,000, depending on features and brand.
   • Mid-range power generators (40-100 kW) are more expensive, ranging from $30,000 to $60,000, depending on load capacity and fuel efficiency.
   • Higher power units (100+ kW) or those used for more extensive industrial applications can exceed $60,000 and reach as high as $100,000 or more.
2. Tier 4 Emission Compliance:
   • Generators that meet EPA Tier 4 Final emissions standards are typically more expensive than those certified under previous standards. Tier 4 Final generators can add 10-20% to the overall price due to the advanced emissions controls.
   • However, purchasing Tier 4 compliant units is a requirement for environmental compliance in the U.S. and will save future costs associated with penalties or regulatory issues.
3. Electrical Classification (Class I, Div. 2):
   • Generators designed for Class I, Division 2 hazardous locations (areas where flammable vapors may be present) are specially constructed and carry additional certifications. Expect a premium of 15-25% for hazardous location-rated equipment.
   • These safety certifications can increase upfront costs but ensure compliance with OSHA and NEC regulations, preventing costly retrofits or replacements later on.
4. Additional Features:
   • Sound attenuation enclosures (for noise control), automatic transfer switches, remote monitoring, and advanced control systems can add to the base price. These features are especially important in complex or critical transloading operations.
   • Fuel tank size and configuration (integrated vs. auxiliary tanks) can also increase costs. For example, larger double-walled tanks designed for long runtime will add a premium to the base price.
5. Brand and Manufacturer:
   • Well-known brands such as Caterpillar (CAT), Cummins, Kohler, Generac, and command a higher price due to their reputation for reliability and extensive service networks. However, these brands often provide longer warranties and better after-sales support, making them worth the investment in the long term.
   • Smaller manufacturers or lesser-known brands may offer lower-cost solutions, but ensure they meet your specific regulatory and operational needs.
6. Operational Costs (Total Cost of Ownership):
   • When budgeting, it’s important to consider the total cost of ownership (TCO) beyond the purchase price. This includes:
     • Fuel costs: Generators running on diesel have varying fuel efficiency rates.
     • Maintenance and service: Regular maintenance and replacement of parts (filters, oils, etc.) will be required.
     • Replacement parts and availability: Reliable manufacturers offer easier access to parts and faster service.

Budget Checklist for Generator Purchase:

• Base cost of the generator based on required kW rating.
• Emission compliance: Ensure Tier 4 Final certification for environmental compliance.
• Hazardous location certification: Verify if Class I, Div. 2 certification is necessary for your operation.
• Fuel efficiency: Consider how long the generator will run and fuel costs associated with its operation.
• Long-term operational costs: Factor in maintenance, spare parts, and service availability.
• Warranty and after-sales support: Consider brands that offer comprehensive service plans or extended warranties.

Investing in a high-quality generator tailored to your operational needs is key to ensuring long-term success. While pricing can vary, making a well-informed decision upfront will help you avoid additional costs related to regulatory non-compliance, operational inefficiencies, or excessive downtime.

More on the Leading Manufacturers of Mobile Diesel Generators

Several reputable manufacturers offer reliable mobile diesel generators designed to meet the demands of the transloading industry:

• Caterpillar (CAT): Known for its robust mobile generator sets with advanced control features and compliance with Tier 4 Final regulations.
• Cummins: Offers mobile generators that combine fuel efficiency, low emissions, and compact designs suitable for transportation.
• Kohler: Specializes in heavy-duty mobile power systems with customizable options to meet hazardous location requirements.
• Generac Mobile Products: Offers mobile diesel generators with integrated lighting and safety features for operations in challenging environments.

By carefully evaluating your power needs, understanding regulatory requirements, and choosing the right equipment, you can ensure that your mobile transloading operations are safe, compliant, and efficient.

For further assistance in specifying mobile generators for transloading applications, feel free to reach out to S&S Technical, Inc. – we are here to help you design the perfect solution!