Type IV Composite CNG Cylinder with Sherwood Valve – 3,600 PSI

Is this ASME or DOT rated, and what does that allow me to do with it?

This cylinder is DOT-rated under FMVSS 304 and NGV2-2007, certifying it for vehicle-mounted natural gas fuel systems and mobile CNG applications. DOT certification allows use in automotive conversion systems, fleet vehicle fuel storage, and portable fuel modules, but not in stationary ASME-governed process applications. The certification runs through January 2034 with a 20-year lifespan from manufacture.

What is the MAWP and capacity at service pressure?

The service pressure is 3,600 PSI (24,800 kPa), which is the rated working pressure for this NGV2 cylinder. Capacity is listed as 11.5 GGE (gasoline gallon equivalent). Type IV composite cylinders typically do not distinguish between MAWP and service pressure the way ASME vessels do—the 3,600 PSI rating is the operating pressure for which the tank is certified.

What is the requalification or inspection status?

The listing does not provide inspection or requalification records. NGV2-2007 Type IV cylinders typically require visual inspection every 36 months or 36,000 miles and are generally not hydrostatically retested like Type I steel tanks, but you should ask the seller for documentation of any inspections performed and verify compliance with the inspection intervals required by your jurisdiction.

What should I inspect before putting it into service?

Inspect the composite overwrap for visible damage, impact marks, cuts, abrasion, delamination, or fiber exposure, particularly near the dome transitions and mounting points. Check the Sherwood valve and the installed stainless adapter assembly for thread integrity, seat condition, and leak-free operation, and verify the manufacture date on the label to confirm remaining service life. Type IV polymer liners can develop permeation or stress cracking that may not be visible externally, so a pressure decay test and thorough visual inspection under good lighting are recommended before returning to service.