Glossary of Terms

Appliance Supply Line

The supply line that connects your second stage regulator to your appliances. Your appliance's supply line may also be called a low pressure supply line and may be constructed of either black iron pipe or soft copper tubing. When a copper supply line is utilized, only forged flare fittings may be used for connections. Your appliance supply line's operating pressure, measured with a manometer, should be 11 inches of water column (4 ounces / sq. in.)

ASME Container

A container manufactured to American Society of Mechanical Engineers standards. An ASME container is a stationary container, filled in place, rather than being replaced with another full container. (see DOT container.) ASME container capacities are measured in water gallons. All 250, 330, 500, 1000 gallon domestic propane storage tanks are ASME containers.

Automatic Delivery

Delivery to your container made on an automatic basis. Frequency of delivery is determined through your historic consumption patterns, degree days elapsed since your previous delivery, and if required, days since your previous delivery.

BTU (British Thermal Unit)

The amount of energy required to raise one pound of water one degree fahrenheit. A gallon of liquid propane contains 91,560 BTU's.

Carbon Monoxide

A colorless, odorless gas that effects the central nervous system and can cause death through asphyxiation. Carbon Monoxide can be produced by improperly vented or poorly adjusted propane appliances.

Carbon Monoxide Testing

Determines precisely what levels of carbon monoxide exist in a suspect area. Any concentration of carbon monoxide above 1200 parts per million is considered Immediately Dangerous to Life and Health. Extended exposure to carbon monoxide above 50 parts per million may cause long term health risks.

GASCO provides quantitative carbon monoxide testing utilizing either a Drager Tube system or a Gas-Tech Carbon Monoxide Analyzer.

Contact Us

Phone: (800) 589-2244

Container Purging

All new containers must be purged of the water and air that exist within the container from the manufacturing process. If left unpurged, a new container will cause regulator failure, improper appliance operation, and refilling difficulties

Degree Days

The difference in temperature between 65 degrees fahrenheit and the average temperature over the previous 24 hour period. In example, if the average temperature over the previous 24 hour period was 30 degrees, 35 degree-days have elapsed.

DOT Container

Department of Transportation Container.A container that is intended to be returned as an empty container to a central refilling facility. Capacities of DOT containers are measure in pounds of water. Examples of DOT containers are 20# grill cylinders, 30# lift truck cylinders, or 100# through 420# cylinders for domestic use.

First Stage Regulator

The regulator located under the tank hood, typically red in color. The first stage regulator decreases the container pressure to first stage supply line pressure, typically less than five psi.

First Stage Supply Line

The supply line that connects your first stage regulator to your second stage regulator. In other words, the supply line that connects your tank to your house.

Hydrostatic Relief Valve

This valve is located on the top of your container, and will open when container pressure exceeds 250 psi. The relief valve automatically closes after venting a small amount of liquid propane to the atmosphere. Your relief valve must have its protective cover in place to keep the elements and debris from hindering its operation.

Integral Two-Stage Regulator

Also called a single-stage regulator. A regulator that decreases container pressure to appliance supply line pressure in one stage. Typically used on domestic DOT cylinder installations.

Liquefied Petroleum Gas (LPG)

Any one of a group of aliphatic hydrocarbons (olefins) including propane, butane and their isomers. Liquefied petroleum gases are kept under pressure.

Maximum Permitted Filling Density

The maximum liquid level to which a propane container should be filled, as to allow for vapor expansion in the container. This permitted filling level is determined by ambient temperature and the temperature of the propane.

Material Safety Data Sheets

Click here for Propane's MSDS.

New Customer

If you own your home, we will extend credit privileges to you prior to the receipt of your credit application. All deliveries to new customers (except new GASCO rental program customers) are CASH ON DELIVERY. If you are unable to be home at the time of your first delivery, you may leave your payment underneath your tank hood. When the delivery is made, your payment will be picked up, and your delivery invoice left in its place.
All tenants are strictly COD.


National Fire Protection Association Pamphlet #54, is the national fuel gas code adopted by most jurisdictions, and governs the installation of gas appliances and their attached piping and venting.


National Fire Protection Association Pamphlet #58, is the national code governing all installations where liquid propane is stored.

Odor Fade

A phenomenon whereby the odorant placed in propane may become neutralized through oxidation. Although little is known of this phenomenon, new containers that have been improperly purged or older containers that have been left open to the atmosphere may be susceptible.

Online Payment

You may pay your invoice online by using the online payment link.
Click here to Make an Online Payment
Credit Card payments made within 10 business days of propane delivery are entitled to a 10 cent per gallon discount.


Prest-o-Lite fitting. A fitting used exclusively for flammable gases. Easily identified by the notches in the hex of the fitting. All POL fittings are tightened by turning counter-clockwise.

Propane's Odor

Propane's distinctive odor comes from the injection of no less than 1.5 pounds of ethyl-mercaptan per 10,000 gallons of liquid propane.

Reading Your Gauge

82% Gauge Your ASME domestic container gauge as it appears when your container is full.

20% Gauge Your ASME domestic container gauge as it appears when you are due for a delivery.

< 20% (Better contact us.)
0% Gauge Your ASME domestic container gauge as it appears when your container is empty.

Oh no!

Regulator Installation

All regulators must be installed in such a manner as to protect the regulator vent from becoming plugged or impeded. Your second stage regulator must be installed at least four feet from any opening that leads to a below-grade area (basement or crawl-space) and at least ten feet from any potential source of ignition (electric service, furnace vent, air conditioner, etc.)

Second Stage Regulator

The regulator that decreases your first stage supply line pressure (~5 psi) to appliance service pressure (~4 oz / sq. in.) Your second stage regulator is typically attached to your building.

System Safety and Integrity Check

Performed by GASCO at the time of your intial installation. All system appliances are checked for proper installation, operation and venting. Your entire system is pressure checked over a 20 minute period to insure system integrity.

Tank Hood

The protective cover on top of your ASME container. Underneath your tank hood you will find your container gauge, vapor service valve, first stage regulator, and the fill valve.
Most GASCO rental ASME domestic containers have a blue hood.

Vapor Service Valve

Located under your tank hood, connected to your first stage regulator. To close your vapor service valve, turn it in a clock-wise rotation. Doing this will shut off your gas supply from the container forward through your appliance service lines. This is your main gas service shutoff point.