CNG Field Service Bulletin
Agility Systems Installation Requirements:
Proximity to Exhaust and Heat Sources
ENP-370
Rev. C: July 20, 2018

1. Introduction
This document is intended as a guideline with respect to installation of CNG containers
(cylinders) and fuel system components near exhaust and heat sources.
Fuel system installers must be aware of heat shields and must not modify or remove them.
A heat shield is defined as a durable metal shield, typically fabricated from aluminum or
stainless steel.
Additional information on proper routing, clipping and installation is available in Agility Fuel
Solutions publication ENP-524, “CNG and LNG Fuel System Routing, Clipping and
Installation Guide.”

Warning Message Used in this Bulletin

Damage to equipment, fuel system or vehicle is possible if instructions are not
followed.

2. Affected Units
Information in this bulletin applies to all Agility Fuel Solutions systems.

3. Corrective Action
Does not apply. This is an informational bulletin.

Fuel system installers must be aware of heat shields and must not modify or remove
them.

4. Heat Shields
A heat shield is defined as a durable metal shield, typically fabricated from aluminum or
stainless steel. Agility uses three types of heat shielding.

4.1 Attached to CNG System
A sheet metal heat shield may be bolted directly to the CNG system, for example, part
numbers 25769399 and 25769340, see Figure 1.

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Figure 1. Heat shields that bolt to the CNG system. Left: 25769399, right: 25769340.

4.2 Attached to Exhaust
A perforated stainless steel heat shield may be purchased at any aftermarket dealer.
Standard sizes are available and mounting clamps are also available. Agility designs and
fabricates a sheet metal heat shield that can bolt to the exhaust.

4.3 Attached to Chassis
Agility designs and fabricates a sheet metal heat shield that can bolt to the chassis. For
example, part number 20103342 shown in Figure 2.

Figure 2. Heat shield part number 20103342 bolts to the vehicle chassis.

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5. Fire Sleeve
Fire sleeve is not considered a heat shield. CNG hose rated at 180°F is still rated at 180°F
when wrapped with fire sleeve: the heat rating is not increased by using fire sleeve.
Fire sleeve contains a flame retardant that prevents the sleeve from igniting and burning
when exposed to direct flame.
Fuel lines shall be shielded using additional means when located in close proximity to the
exhaust.

6. Agility Systems Requirements
The following are Agility minimum requirements and are intended as a guideline. Additional
heat shields and precautions may be taken to exceed these requirements.
1. Minimum 2.0 inch gap between exhaust and an all-metal fuel line:
a. No heat shield required.
2. Minimum 2.0 inch gap between exhaust and non-metallic fuel line:
a. Metal heat shield required.
b. Fire sleeve recommended around non-metallic fuel lines in addition to heat
shield.
3. Minimum 2.0 to 3.5 inch gap between exhaust and fuel system covers:
a. Requires heat shield between exhaust and system covers.
4. Minimum 3.5 to 8.0 inch gap between exhaust and fuel system covers:
a. No heat shield required.
In some cases, heat sources may be near CNG fuel system covers. The maximum
allowable (steady-state) temperature of a composite cover is 150°F. The maximum
allowable (steady-state) temperature of a metal cover is 180°F.
1. Minimum 4.0 to less than 8.0 inch gap between exhaust piping and fuel system
covers when exhaust piping is below the fuel system covers:
a. Requires heat shield between exhaust and system covers.
2. Minimum 8.0 inch gap between exhaust piping and fuel system covers when
exhaust piping is below the fuel system covers:
a. No heat shield required between exhaust and system covers.
3. Exhaust outlet below fuel system covers must divert exhaust gases away from fuel
system such that no exhaust gases impinge on the fuel system.
Contact Agility Fuel Solutions Customer Care Group if local heating of the covers exceeds
these limits.

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9. Warranty Information
Does not apply.
If you have any questions, contact Agility Fuel Solutions Customer Care: +1 949 267 7745,
toll free: +1 855 500 2445 or [email protected].
Proprietary Statement
The information provided within this document is proprietary and confidential. All prior
versions, including updates and revisions forwarded separately, are proprietary. The
information provided by Agility Fuel Solutions to its customers and clients is solely for the
use of those customers and clients. No portion of this manual may be reproduced or
distributed without express written consent of Agility Fuel Solutions. Agility Fuel Solutions
reserves the right to utilize the intellectual property contained within this publication as
content for any other publication produced by Agility Fuel Solutions.
Trademark Notice
Agility® and TUFFSHELL® are registered trademarks of Agility Fuel Solutions. Drop-NGo™ is a trademark of Agility Fuel Solutions. Trademarks of other manufacturers are the
property of their respective companies.
Agility Fuel Solutions
3335 Susan Street Suite 100
Costa Mesa, CA 92626 USA
www.agilityfuelsolutions.com

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