NGVConnection Newsletter - February 2017

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Diagnosing Low Power in Heavy-Duty Natural Gas Engines

By Gordon Larsen and Bill Marchetti, NGVi Technical Instructors

In NGVi’s work training heavy-duty natural gas vehicle technicians, the number one problem they report is diagnosing low power conditions. When a Cummins-powered heavy-duty natural gas vehicle is brought into the maintenance facility with a complaint of low power, the technician wants to diagnose and repair the problem as quickly as possible. But even an experienced diesel technician can have difficulty with natural gas engines because they are different—significantly different—than their diesel counterparts.

As a general rule, both the Cummins ISL G and ISX12 G engines use significantly different technology than today’s comparable diesel engines. That’s not a bad thing—but it does mean that technicians need to have a full understanding of the systems and the fault code based diagnostic constraints for these engines, as well as how both the fuel and the fuel system can affect performance.


Join Us for a Live One-Hour
Tech Talk Training Session

When There's No Fault Code:  
Diagnosing Cummins Natural Gas Engine Performance Issues


Date: Thursday, March 2, 2017
Time: 11:30 a.m. PT/2:30 p.m. ET

In this interactive training session, NGVi’s expert trainers will discuss the primary causes for low power in Cummins natural gas engines, how to diagnose them, and how to resolve them.

The Tech Talk will include information taken straight from NGVi's more in-depth Heavy-Duty NGV Maintenance and Diagnostics Training, along with real-life examples, followed by a question-and-answer session.




A quick comparison of natural gas
heavy-duty engines to diesel engines illustrates this point. Unlike diesel engines, Cummins natural gas engines have two controllers—the electronic control module (ECM), which diesel engines have and the ignition control module (ICM), which diesel engines do not have. In addition, natural gas engines have different sensors than diesel engines. Natural gas engines may have up to 17 sensors—16 being analog sensors and only one being a CAN-networked digital sensor. Most of these analog sensors send a voltage signal to the ECM. The voltage signals are either resistance applied to a reference voltage or a direct voltage.

There are 10 actuators on Cummins natural gas engines. In this configuration, seven actuators are electro-mechanical and can send indirect trouble codes. The other two are fully mechanical actuators which send no codes.

There are three mechanical devices on Cummins natural gas engines—the boost line, the Wastegate actuator and the low pressure regulator—and none of these devices send trouble codes.

It is the complexity of the engines themselves, the uniqueness of the components and the number of components that do not send pinpoint direct component fault codes, that can make diagnosing low power a challenge. Some problems—like Code 1861 Lean Condition—will set a general code, but the technician needs to investigate a number of potential sources before he or she identifies the specific source. Other problems won’t set a fault code at all.

When diagnosing low power, it is helpful to look at five general areas. Areas that don’t set codes include turbocharger failures, ignition failures, fuel component failures, mechanical failures and charge air system component failures.

Some turbo failures, like boost pressure sensor, turbocharge turbine intake temperature sensor and the turbo intake humidity/pressure temperature sensors, will set fault codes. Those that do not set codes are more problematic, including turbocharger failure, turbocharger Wastegate failures and turbo boost line failure. One potential problem that is often overlooked is Wastegate failures, and there are several causes that must be investigated.

Ignition coil, coil extension, or plug failures can cause an engine to misfire and lose power. The ECM diagnostics will set misfire codes but do not pinpoint the exact component that has failed.

Fuel failures are frequently the cause of low power complaints, and can involve a multitude of components. Check both the primary and secondary regulators, contaminated fuel (common for natural gas engines because of oil carryover from CNG fueling stations), and clogged components such as the coalescing filters, the laminar flow screen and the fuel mixer.

Mechanical failures can also be a cause of low power in heavy-duty natural gas engines. The valve lash maintenance at the recommended intervals is critical to engine life and performance.

As with any unfamiliar technology, training is the key. When technicians know the unique natural gas engine components and fuel characteristics, as well as where to start to diagnose problems even when there’s no specific code, they become more proficient at their jobs…vehicle downtime is reduced…and maintenance costs are decreased.


NGVi’s Heavy-Duty NGV Maintenance and Diagnostics Training is the only ASE CASE Accredited technician training that covers both the fuel system AND the engines. To learn more, click here.

The Road to Safe Methane Detection: Infrared and Catalytic Sensors

By Mark Rehak, Divisional Sales Director, US, Draeger, Inc.

When hazardous gases and vapors build up and reach dangerous concentrations, our sensory organs are often unable to detect these airborne hazards. As a result, we seek and develop solutions that maximize our safety and protect against these risks before they escalate and become critical health and infrastructure threats. Enter: Sensors.

The sensor is an important component that resides inside a gas detector and serves as a mini-alarm system. It reacts with the gas present in the environment to produce an electrical signal that corresponds linearly with the gas’s concentration level. Furthermore, the reliability in which harmful airborne substances can be detected largely depends on the sensors used and the substance to be detected. For a stable, flammable gas such as methane, one must consider the different scenarios where a catalytic or infrared sensor is the wisest choice, and with the help of Dräger’s methane gas detection systems, facilities can maximize safety while minimizing maintenance.

Infrared Sensors

Infrared (IR) sensors are a sophisticated breed of sensors that are ideal for applications in which demands for functional safety are high. Unlike catalytic bead sensors that rely on oxygen for the proper reaction to determine gas concentrations, IR technology does not. This allows for its use as a reliable tool in atmospheres that could become oxygen deficient from large hydrocarbon releases in enclosed spaces.

When substances contain hydrocarbons, their C-H bonds absorb part of the infrared radiation emitted from the sensor. As a result, this slightly weakens the intensity of the emitted light in a specific frequency, which light-sensitive pyro-electric detectors register while downstream electronics generate a signal that indicates whether or not a gas concentration is present.

IR sensors have the capability to detect gas concentration through infrared absorption ranging from a few hundred parts per million (ppm) and up to 100 percent by volume. This means IR sensors are able to detect flammable gases and vapors within their 0-100 percent LEL ranges, and they can be used for the early detection of even the smallest leaks, so serious damage can be swiftly avoided.

When it comes to IR sensors, there are several options available that can help optimize safety in the workplace. For example, open path detectors such as the Dräger Polytron® Pulsar detector consist of a transmitter and a receiver that are placed on opposite sides of the facility. A continuous beam runs between the two, spanning across the length of the room, and when gas leaks occur, any gas clouds that form and intercept the beam are automatically detected. In outdoor facilities where external factors cannot be controlled, continuous communication between the transmitter and receiver in the Dräger Polytron Pulsar allows the system to adapt to harsh environmental conditions. The Dräger Polytron Pulsar contains four high-power xenon lamps that are paired with complex algorithms that vary in intensity and frequency in accordance to the ambient conditions. This combination, along with the digital link between the transmitter and receiver, allows the device to be easily and properly aligned, while protecting its measurements from external influences such as cross talk, solar radiation or resonance effects associated with vibration from machinery, as well as environment changes along the beams such as fog, mist and snow.

Open path IR sensors can also be beneficial based on the type of facility that needs gas detection. While point gas detection devices measure the exact concentration of the gas at that particular location (further stressing the importance of sensor placement), open path detectors take the gas’s average concentration over the entire beam path, which can greatly benefit and compliment point detectors for an overall safety level. In liquefied natural gas (LNG) facilities, for example, if LNG is spilled or a leak occurs, initially, the cold, dense vapors can stay at ground level near the release point. But as the vapors warm, they will disperse and dilute with the ambient air quickly. Therefore, the gas can be presented as a very high concentration over a small area or a very large volume of low concentration gas over a large area. Depending on the placement of the point detectors, the detectors could read a very high alarm, a very low alarm or no alarm. In the case of open path, only the number of gas molecules in the entire beam path are considered, and it does not differentiate between a small cloud of high concentration or a large cloud of low concentration. Either scenario can present the same danger. Taking an average concentration over a wider area can provide a much clearer picture of what airborne substances are lurking and placement concerns are not as critical.

With the new integration of wireless technology, IR sensors have broadened their capabilities. The GasSecure GS01 combines a single-beam, triple-wavelength IR technology offering reliable detection for demanding industrial applications. Using wireless communication that is based on the open ISA100 Wireless standard, it can seamlessly be integrated with other commercially available field wireless devices. This not only allows users to customize their gas detection systems based on their needs, but also greatly improves installation flexibility. Furthermore, its SafeWireless communication system provides reliable, yet fast, 5-second response time with full control of network traffic all while providing a very long life battery. By adapting this no-cable system, facilities can streamline workflow, reducing total project costs by up to 60-80 percent.

An IR sensor’s advantages over a catalytic sensor are that it is not subject to sensor poisoning, has a much more stable reading over a longer period of time, greatly reducing the calibration requirements, can reliably monitor in low oxygen atmospheres and has no mode of failure that can go undiagnosed. While IR sensors generally add to the upfront cost of the device, the cost is easily offset by offering a much better long-term cost of ownership. Furthermore, all hardware needed to perform the gas measurements, such as light source detectors, signal amplifiers, processors, memory chips, etc., are protected against external influences. The Dräger Polytron 8700, for example, is built with harsh environments in mind. Using a solid, explosion-proof stainless steel housing, the enclosure acts as a seal to keep the interior components safe from dirt, moisture and corrosive gases to prolong the instrument lifetime, and protect it from any factors that may impair gas measurement.

Dräger IR sensors are continuously monitored internally, and offer full diagnostics. Any component’s failure immediately triggers a fault alarm—providing a true, fail-safe operation.

Catalytic Sensors

Historically, catalytic sensors have been favored due to their lower initial cost and their ability to detect most combustible gases. In order to measure flammable gases such as methane, the gases are burned through a process called oxidation. Oxidation requires oxygen, fuel and a catalyst that is attached to a ceramic body called the pellistor. The greater the energy generated during the oxidation process, the higher the temperature will rise on the measurement pellistor. The temperature is measured as resistance and compared to a reference pellistor. The delta between the reference and measurement pellistors is then output as a proportional gas concentration.

It is important to have a holistic understanding of a sensor’s advantages and limitations. As previously noted, catalytic sensors rely on a heated oxidation process to accurately detect gas concentrations. Because of the heat generated on the pellistors, it is necessary to employ a flame arrestor (commonly called a “frit”) on the face of the sensor to keep any possibility of ignition from happening outside of the sensor. This flame arrestor creates a barrier and torturous path that the gasses must migrate through to reach the sensor. This can create a bit of a lag in the response time of most sensors. Dräger has designed a unique flame arrestor that greatly reduces this effect, affording a much shorter time for the gas to migrate to the sensor and offering a much faster response time.

Second, a catalytic sensor’s ability to accurately and reliably detect gases can be weakened by poisoning through exposure to substances such as: silicones, tetraethyl lead, halogenated hydrocarbons, sulfur compounds and organophosphorus compounds. Sensor poisoning is a potential issue that can go undiagnosed without frequent testing. To help identify and safeguard against catalyst contamination, clogged frits, as well as to ensure all around proper working functions, it is necessary to frequently conduct appropriate bump tests and calibrations to ensure a reliable measurement. In addition to staying compliant with OSHA’s guidelines, always review the manufacturers’ instruction manuals to identify the best maintenance method for your equipment.


At the end of the day, open path and point detection both serve their purposes, and both catalytic and IR sensors suit specific demands.

To maximize safety, pursuing a comprehensive understanding of the technology ins-and-outs of your sensors is critical when tailoring a gas detection system to suit your needs.

For more information, please visit

The Value of Certification

By Kasia McBride, Marketing Manager, NGVi

Professional certification refers to a voluntary process of skills and knowledge assessment, administered by a third party organization, to determine whether an individual can demonstrate a specific level of competency in a particular job role. It is based on industry-recognized standards, defined by specific conditions, and is meant to establish a baseline of competency. Assessments for the purposes of certification have emerged as key elements assuring competency across many industries.

As technology evolves, gaps between an employee’s base education and any industry-specific requirements widen over time, unless there is continued education. Many factors combine to draw professionals toward specialization. The need for skill advancement to keep pace with technology reflects a drive for greater efficiency, better performance, lower cost, and is essential for any sustainable business. For the NGV-specific transportation industry, where vehicle technicians, fuel system inspectors, and other operational personnel must acquire and maintain specialized skills and knowledge, certification promises to raise the bar on acceptable standards of performance.

There are many reasons why organizations pursue professional certification for their employees.

1. Greater peace of mind/Improved risk management

For many companies, certification gives employers a guarantee that their employees have sufficient knowledge and mastery of a full range of skills required to do real-world and complex job duties responsibly.

CNG fuel system inspectors, for instance, who handle detailed inspections of high-pressure fuel systems, have a huge responsibility to detect damage which could otherwise lead to life-threatening situations. Certification is the most prudent way for organizations to ensure their technicians demonstrate the required knowledge and competencies to perform their job correctly.

Technician certification by third party industry experts assures that organizations can more confidently rely on their workers with a high degree of consistency and safety, while also protecting the company from potential liabilities associated with vehicle failures and security risks.

2. Reduced operating costs

Although many employers recognize that employee development is important, they often view it as an expense rather than an investment. Research has shown that employees with a professional certification are more productive. That’s because certification better prepares them to deal with day-to-day challenges and gets the most out of new technologies. Certified vehicle technicians are able to diagnose a problem faster with more accuracy. This, in turn, eliminates service failures, resulting in fewer mistakes and a greater number of vehicles in service daily. Because employers tend to promote employees they trust, certification status enhances career potential.

By certifying their vehicle technicians as proof of their comprehensive capabilities (like correctly detecting fuel system component failures or damage) organizations can minimize serious economic impacts, such as vehicle downtime, or lengthy maintenance cycles. This can save organizations thousands of dollars per vehicle.

3. Improved stakeholder relationships

Having certified employees who have been verified by a third party organization translates into better customer relations and greater customer loyalty. It shows customers that the company holds its staff to the highest quality standards. Fleet customers, for instance, who often rely on the knowledge and skills of vehicle technicians, can feel more secure knowing their fleets are in certified hands.

Employees benefit also. Certification gives them recognition of competency, shows commitment to the profession, motivates them, gives them peace of mind and confidence, helps with career advancement, and provides them with a sense of pride and professional accomplishment.

4. Public Safety

CNG fleets that routinely operate in populated residential areas are responsible for thousands of lives every day. For fleets such as transit, refuse, or school districts, obtaining professional certification for their technicians is especially important. These technicians have an enormous responsibility, because service mistakes, improper installations or undetected damage to the CNG fuel system could result in dangerous incidents, affecting not only the safety of fleet employees but also the general public.

5. Business credibility

Professional certification is an independent confirmation of credibility. This is instrumental for organizations to effectively demonstrate what mastery their staff has attained in their field within the organization, with business partners and with their customers. Certification provides assurance that the individual possesses the required competencies and is, therefore, a source of credibility.

Why NGVi’s Certification for CNG Fuel System Inspectors Is Important

NGVi launched its CNG Fuel System Inspector Certification program in September 2016, and since that time has certified more than 100 technicians. The main goal of NGVi’s CNG Fuel System Inspector Certification program is to help organizations ensure that their NGV technicians have demonstrated the adequate level of competency and knowledge required to conduct successful CNG fuel system inspections, according to all federal codes and standards, as well as industry best practices.

Since 2008 when the NGV industry recognized that inspecting all high-pressure fuel system components was the only way to provide maximum risk management, industry best practice recommends completing an entire CNG fuel system inspection in conjunction with federally required cylinder inspections.

CNG fuel system inspections require detailed knowledge of manufacturing codes, installation codes and inspection codes—all of which change and are updated regularly. Qualified CNG Fuel System Inspectors must be able to thoroughly inspect all components of CNG fuel systems, correctly document their findings, assess any damage, and determine the proper course of action.

Because these inspections are complex processes during which damage are often not easy to identify for those unfamiliar with the components involved, proper training and certification is essential and must be a fundamental part of every effective safety program for NGV fleets and dealerships.

As a rigorous, independent assessment, NGVi’s CNG Fuel System Inspector Certification was developed based on a detailed job study of tasks technicians must apply during an actual inspection. Because of the practical, real-world application of knowledge, certification gives technicians the opportunity to demonstrate skills accurately and safely, and at the same time, it offers their employers an extra level of assurance and confidence in technician competency.

There are professional certifications available across a wide variety of fields and industries, but the greater technological advancement, the greater the need for ongoing employee certification. In the transportation industry, especially among NGV fleets that routinely operate in populated residential areas, certification of CNG fuel system inspectors just makes sense.

For more information about NGVi’s CNG Fuel System Inspector Certification program, visit our website at

CNG Fuel Price Report
From Clean Cities Alternative Fuel Price Report published by National Renewable Energy Laboratory (NREL) for DOE's Clean Cities Program

Overall Average Fuel Prices (as of October 2016)


Nationwide Average Price for Fuel This Report

Nationwide Average Price for Fuel Last Report

Change in Price This Report vs. Last Report

Units of Measurement

Gasoline (Regular)




per gallon





per gallon





per GGE

NGVs and CNG in the News


Local company lands grant to purchase CNG vehicles -- KSTU-FOX 13

A. Schulman is sizing up natural gas market

Sanitation service adds CNG haulers -- The Waunakee Tribune

REV Group - Commercial Bus Division (ENC) - Delivers Heavy-Duty CNG Fueled Shuttle Buses to DFW Airport
-- Business Wire

Upcoming Training from NGVi

NGV Essentials and Safety Practices CNG Fuel System Inspector Training
March 28, 2017 Charlotte, NC

With a focus on safety, this one-day course teaches technicians the fundamentals of natural gas, CNG and LNG fuel systems and maintenance practices for NGVs.

March 29-30, 2017 Charlotte, NC
April 12-13, 2017 Egg Harbor, NJ

Two-day session that provides you with the proper techniques for inspecting CNG fuel systems, including on-board compressed natural gas fuel storage cylinders.

Heavy-Duty NGV Maintenance
and Diagnostics Training

Heavy-Duty NGV Maintenance and Diagnostics Training

NGVi Cylinder Fuel System Inspector Training
April 10-11, 2017 Egg Harbor, NJ

Prepare your NGV technicians to safely and cost-effectively maintain and diagnose the components of all CNG fuel systems, as well as the Cummins ISL G and ISX12 G engines.

This comprehensive, two-day course includes operational theory and diagnostics, with more than a dozen hands-on exercises.


CNG Fueling Station Design Training 

April 24-25, 2017 Spring Valley, NV

Two-day course that offers the detailed technical information needed to successfully size, design and specify a CNG fueling station.

CNG Fueling Station Operation and Maintenance Training

April 26-27, 2017 Spring Valley, NV

Two-day session that provides you with the proper techniques for operating and maintaining CNG fueling stations to help avoid oil carryover and water in the natural gas stream.

NGVi CNG Fueling Station Operation and Maintenance Training

Register Now


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Upcoming Training

Level 1: NGV Essentials
and Safety Practices

August 21, 2018
Atlanta, GA

Level 2: CNG Fuel System
Inspector Training

August 22-23, 2018
Atlanta, GA

Level 1: NGV Essentials
and Safety Practices

September 11, 2018
Boothwyn, PA

Level 2: CNG Fuel System
Inspector Training

September 12-13, 2018
Boothwyn, PA

Essentials of CNG Station Planning,
Design and Construction

September 24-25, 2018
Las Vegas, NV

Essentials of CNG Station
Operation and Maintenance

September 26-27, 2018
Las Vegas, NV

Level 1: NGV Essentials
and Safety Practices

October 2, 2018
Sacramento, CA

Level 2: CNG Fuel System
Inspector Training

October 3-4, 2018
Sacramento, CA


Register Now »

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About NGVi

Natural Gas Vehicle Institute is North America’s leading provider of training and consulting on natural gas as a transportation fuel.

Our services address the full range of natural gas vehicle and fueling issues, including:

Technical consulting services – Sizing and designing compressed natural gas fueling stations, vehicle assessments and technical assistance for fleets, CNG fueling station troubleshooting, natural gas vehicle maintenance facilities upgrades, liquefied natural gas fleet and fueling management.

Technical training – NGV Essentials and Safety Practices, CNG Fuel System Inspector Training, Heavy-Duty NGV Maintenance and Diagnostics Training, Light-Duty NGV Maintenance and Diagnostics Training, CNG Fuel System Design and Installation Training, Essentials of CNG Station Operation and Maintenance Training, Essentials of CNG Station Planning, Design and Construction Training and CNG/LNG Codes and Standards Training for Fire Marshals and Code Officials.


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