Orbit Series
Mars
Compact CNG Cylinder
A compact 6.8-inch OD Type III CNG cylinder rated to 3,600 PSI, available in 8-liter and 10-liter configurations for vehicle, vessel and other space-constrained compressed natural gas systems.
Compact compressed natural gas storage
CNG storage in a 6.8-inch diameter package.
Mars is available in 8-liter and 10-liter configurations while maintaining a nominal 6.8-inch outside diameter, making it a practical option where installation space is limited.
Steelhead's supplied engineering drawing identifies the product as a Type III pressure vessel with a 6061-T6 aluminum liner and a 248 bar / 3,600 PSI operating pressure. The standard offering uses a Sherwood CNG valve on Port 1 and a plugged Port 2.
3,600 PSI
248 bar operating-pressure CNG platform.
8L & 10L
Two compact standard-volume configurations.
6.8 in OD
Nominal outside diameter of 6.8 inches.
Technical data
Mars configurations
Dimensions and masses below are taken from Steelhead's supplied 3,600 PSI CNG Gas Bottle Product Family drawing, Rev A.
| Nominal Volume | Length without Valve | Length with Valve | Mass without Valve | Nominal OD |
|---|---|---|---|---|
| 8 L (2.1 gal) | 652 mm (25.6 in) | 704 mm (27.7 in) | 8.5 kg (18.7 lb) | 172.7 mm (6.8 in) |
| 10 L (2.6 gal) | 741 mm (29.1 in) | 792 mm (31.2 in) | 9.0 kg (20.0 lb) | 172.7 mm (6.8 in) |
Confirm current production drawings and approved valve configuration with Steelhead before final system integration.
Standard CNG configuration
Purpose-built around compact CNG integration.
Type III Construction
Steelhead's drawing identifies a Type III vessel with a 6061-T6 aluminum liner.
Port 1
Sherwood CNG valve in the standard configuration shown by Steelhead.
Port 2
Plugged port in the standard configuration.
Why Mars
Compact dimensions for vehicle and vessel CNG systems.
Steelhead positions the 6.8-inch OD 3,600 PSI family for CNG storage on vehicles and vessels, either as a single cylinder or as part of a bundled system.
The two standard capacities let integrators choose between 8-liter and 10-liter storage while maintaining the same nominal vessel diameter and a common platform architecture.
CNG compliance
Designed for certified on-vehicle CNG applications.
Steelhead's current product catalog identifies the 6.8-inch OD, 3,600 PSI CNG family with FMVSS 304 and NGV2:2023 certifications.
FMVSS 304
Listed by Steelhead for the 6.8-inch OD CNG product family.
NGV2:2023
Listed by Steelhead for the 6.8-inch OD CNG product family.
CNG Service
The source material identifies compressed natural gas as the intended stored gas.
Valve & port options
Standard CNG hardware with additional options available.
The engineering drawing shows a Sherwood CNG valve and plugged opposite port in the standard configuration. Steelhead's catalog also identifies Oasis, Sherwood and plug options for the 6.8-inch CNG family.
Sherwood
Standard valve shown on the supplied product-family drawing.
Oasis
Listed by Steelhead among available CNG valve/end-plug options.
Plugged Port
Standard opposite-end arrangement in the supplied drawing.
Applications
Built for compact mobile CNG storage.
Steelhead's supplied catalog positions the 6.8-inch CNG platform for on-vehicle and vessel gas storage as a single cylinder or in bundles.
Vehicle CNG Storage
Compact high-pressure CNG storage for space-constrained vehicle installations.
Vessel / Marine Applications
Steelhead identifies vessel CNG storage among the applications for this product family.
Single or Bundled Systems
May be integrated as an individual cylinder or as part of a multi-cylinder package.
Engineering support
Need a compact CNG cylinder for a constrained installation?
Steelhead can help evaluate capacity, packaging, valve configuration and integration requirements for your CNG application.
8L vs. 10L Selection
Compare the two standard lengths against available space and required CNG capacity.
Valve Configuration
Review standard and available CNG valve or plug options with the Steelhead team.
Bundle Integration
Evaluate single-vessel or multi-cylinder packaging for the intended vehicle or vessel system.
Public product naming
Mars is the commercial name for this compact CNG platform.
Steelhead's engineering drawing uses the internal SH24 designation. The public website intentionally uses Mars to distinguish this commercial CNG configuration from other Steelhead products that may use SH24 internally.
Talk to a pressure vessel expert
Is Mars the right CNG cylinder for your system?
Share your required capacity, available envelope, valve and installation requirements with Steelhead.