Park, switch off, pay, open the fuel door, push the NGV1 nozzle onto the receptacle and pull the lever to lock it, press start, wait three to five minutes for a car or ten to fifteen for a truck, unlock and remove. The dispenser stops on its own at 3,600 psi (or 3,000 at older sites). Fills are shorter in hot weather because a warm cylinder holds less. Check the listing's badges before you drive there: quick-fill, the right pressure, your vehicle class, and a card you carry.
The badges on every listing
| Badge | What it means | What to do about it |
|---|---|---|
| Quick-fill | High-pressure storage on site fills you in minutes, like a gas pump. | This is what a passing driver wants. |
| Time-fill only | Vehicles are hooked to the compressor for hours, usually overnight. Built for fleets that park on site. | Not useful on a trip. Find the next quick-fill. |
| Quick + time-fill | Both. A fleet yard that also has a fast dispenser. | Use the quick-fill dispenser. |
| 3,600 psi / 3,000 / 3,600 psi | The pressures the station dispenses. | Match your cylinder. A 3,600 psi cylinder at a 3,000 psi-only station gets about 80 percent. |
| Class 8 OK | DOE marks the site for heavy-duty vehicles: canopy height, turning room, dispenser flow. | Tractor-trailers: only go where you see this. Cars fit anywhere. |
| Up to medium-duty / Light-duty only | Box trucks and vans, or cars and pickups only. | Trucks: skip. |
| RNG | The station reports dispensing renewable natural gas. | Matters for fleet carbon reporting; the fill is identical. See the RNG guide. |
| 24 hours | The DOE hours field says 24 hours. | No badge means check the hours line on the listing; utility sites often close with the office. |
| Not re-verified in 18+ months | DOE has not confirmed the record in a year and a half. | Call ahead if it is the only station on your leg. |
Step by step at a quick-fill station
- Park with the fill receptacle toward the dispenser and switch the engine off. Some stations post a rule against phones or smoking at the island; treat it like a gasoline pump.
- Pay. Credit or debit card at the dispenser, or a fleet card. Some sites take only a network card; the listing tells you.
- Open the fuel door and remove the dust cap from the receptacle. The receptacle is a small stub with a groove, not a hole.
- Choose the nozzle. Cars and pickups use the standard NGV1 light-duty nozzle. Heavy-duty islands have a larger, faster nozzle; a car's receptacle will not accept it, and vice versa. Some dispensers also have separate 3,000 and 3,600 psi hoses; pick the one that matches your cylinder label.
- Push the nozzle onto the receptacle and lock it. Most nozzles lock by pulling a lever or rotating a collar; you will feel it seat. Nothing flows until it is locked and the dispenser has pressure-tested the connection.
- Press start and wait. You will hear gas flowing and the hose will stiffen. The dispenser stops itself when the cylinder reaches service pressure, adjusted for temperature.
- Unlock and remove the nozzle. A brief hiss as the hose vents its last few cubic inches is normal. Replace the dust cap.
A Civic-size fill takes three to five minutes. A Class 8 tractor with a 120 DGE package takes ten to fifteen minutes at a truck-stop dispenser, longer at a light-duty island.
3,000 vs 3,600 psi
Every CNG cylinder has a service pressure on its label, and nearly everything built since the early 2000s is 3,600 psi. Older vehicles and a few older fleet stations are 3,000 psi. A 3,600 psi vehicle can fill at a 3,000 psi station safely; it just gets roughly 80 percent of its capacity. A 3,000 psi vehicle must not be filled at 3,600 psi, and a properly built 3,600 psi dispenser will not physically connect to a 3,000 psi receptacle, since the NGV1 nozzle profiles differ. The pressure badge on each listing comes straight from the DOE record.
Why a hot fill stops early
Compressing gas into a cylinder heats it. The dispenser is targeting 3,600 psi at a reference temperature of 70°F, and a cylinder that is hot from the sun and hotter from the fill reaches that pressure with less gas in it. Good dispensers apply temperature compensation, overfilling slightly to allow for cooling, but there is a limit. In practice a fast fill on a 100°F day can leave you at 80 to 90 percent of rated capacity, and the gauge will drop a little as the tank cools. Plan long legs at 80 percent of rated range, and expect fuller fills on cool mornings and from slower dispensers.
Time-fill
A time-fill post is a hose with no storage behind it: the compressor feeds the vehicle directly at whatever rate it produces, typically taking six to twelve hours to fill a truck. Fleets use it because it is cheap to build (no storage cascade), gives a cooler and therefore fuller fill, and matches vehicles that park overnight anyway. A few public listings are time-fill only; they are almost always municipal or utility yards that technically allow public access. The badge will save you the trip.
Paying
Most public stations accept Visa and Mastercard, and truck stops and networks add fleet cards: WEX (Wright Express), Voyager, Comdata, EFS, Fleet One, Fuelman, and network-specific cards from Clean Energy and Trillium. Each listing shows the cards in the DOE record; the networks page summarizes which cards each operator takes most often. Utility-hosted stations sometimes require an account with the utility, which is shown as "Proprietor card" or a card-key note in the access line.
FAQ
How long does it take to fill a CNG car?
About three to five minutes at a quick-fill station. A heavy truck takes ten to fifteen minutes at a truck-stop dispenser. Time-fill stations, built for fleets, take several hours.
Can I fill a 3,600 psi CNG tank at a 3,000 psi station?
Yes, safely, but you will get about 80 percent of the tank's capacity. The reverse, filling a 3,000 psi tank at 3,600 psi, must not be done and the nozzle profiles are designed to prevent it.
Why did my CNG fill stop before the tank was full?
Compressing gas into the cylinder heats it, and a hot cylinder reaches 3,600 psi with less gas inside. Fast fills on hot days commonly stop at 80 to 90 percent of rated capacity. Cooler weather and slower dispensers give fuller fills.
What is a time-fill CNG station?
A station where vehicles connect directly to a compressor for hours, usually overnight, instead of filling from high-pressure storage in minutes. They serve fleets that park on site and are not practical for a passing driver.
Do I need a special card to buy CNG?
Usually not; most public stations take Visa and Mastercard. Truck stops and networks also take fleet cards, and a few utility-run sites require an account card. Each listing on this site shows what the DOE record lists.
Find a station
Every public CNG station, with the badges this guide explains.